HST is a 2.4-m telescope that was carried into orbit on April 24, 1990, aboard the orbiter Discovery. Until the end of 1993, its performance was affected by the primary mirror's spherical aberration, which was discovered shortly after launch. The first HST servicing mission, carried out by the Endeavour astronauts in December 1993, restored the optical performance for which the telescope was originally designed, and corrected several other problems that had arisen since launch. Cycle 6 observations are now underway, and Cycle 7 observing will begin in mid-1997.
The second HST servicing mission (SM97) is currently scheduled for 13 February 1997 and will involve several changes relevant for Cycle 7 proposers. Two new science instruments, the Space Telescope Imaging Spectrograph (STIS), and Near Infrared Camera and Multi-Object Spectrometer (NICMOS), will have replaced the Goddard High Resolution Spectrograph (GHRS) and the Faint Object Spectrograph (FOS), respectively. A new Solid-State Recorder (SSR) and a refurbished analog tape recorder will both be installed-these will provide much improved data transfer capabilities. A refurbished Fine Guidance Sensor (FGS) with improved optics and resulting greater sensitivity will replace FGS-2; at least for Cycle 7, FGS-3 will remain the science astrometer. Orbital verification of the new hardware is scheduled for completion by the nominal 1 July 1997 start date for Cycle 7. Some of the more specialized uses of the new instruments and many of the detailed on-orbit science calibrations will be phased in during Cycle 7.
The instruments continuing operations after the second servicing mission are the Wide Field and Planetary Camera 2 (WFPC2), the Faint Object Camera (FOC including its corrective optics in the COSTAR) and the astrometric Fine Guidance Sensor (FGS-3). The principal capabilities of the refurbished HST observatory will include high-resolution ultraviolet, optical and near-infrared imaging and a broad range of spectroscopic capabilities over these wavelength domains.
Part I of this document gives a summary of the policies and procedures for proposing Cycle 7 HST observations and for requesting funding to support research on archival HST data. Part II provides an overview of HST's current technical capabilities. Further detailed information about the telescope and each Science Instrument (SI) is provided on-line or in documents that are available from STScI, as described in §2. Part III of this Call for Proposals (CP) consists of the Phase I Proposal Instructions, which contain detailed instructions for obtaining the proposal templates, preparing them, and submitting them electronically and on paper.
Although the proposal forms and submission procedures have been modified only slightly for Cycle 7, it is still important that all proposers, including those who proposed in previous cycles, read this document carefully. Proposers should particularly note the following features of Cycle 7:
As in previous cycles, there will be separate proposal submission deadlines depending on whether (1) the filled-in LaTeX template file is sent to STScI by electronic mail in addition to the paper proposal or postscript file, or (2) proposals are submitted entirely on paper.
The Cycle 7 proposal deadlines are as follows:
Postscript-plus-LaTeX template submissions: September 13, 1996
Paper-plus-LaTeX template submissions: September 13, 1996
Paper-only submissions: September 6, 1996
Unfortunately, because of the processing steps that must commence immediately upon receipt, it will not be possible to consider proposals that are submitted after these deadlines.
Observing proposals must contain a summary of the proposed observing program, including the targets that are to be observed and their celestial coordinates, and the desired instrument modes and filters or dispersers. In addition, a calculation of the number of spacecraft orbits needed to accomplish the observing program must be carried out and summarized in the proposal. Thus it is important that proposers consult technical documentation about the capabilities and sensitivities of the instrument(s) that will be used to obtain the observations. Where necessary, proposers should discuss their requirements with appropriate STScI experts (contacts provided via the STScI Help Desk) before submitting their proposals. The following subsections describe the various sources of information that are available to proposers.
The current set of technical documents is listed in Table 1a. Table 1b lists the manuals, which have not been updated due to the removal of these instruments from the spacecraft, and are now of interest primarily for archival proposers and for those analyzing pre-SM97 data.
Table 1: HST Technical Documentation
New editions of the instrument technical handbooks have been prepared for each of the current Scientific Instruments (SIs), reflecting instrument performance following the first servicing mission. Handbooks for the new instruments, STIS and NICMOS, are also being prepared, based on the pre-launch and design data. Electronic versions of all Instrument Handbooks are already available on-line, and additional information will be posted separately as it becomes available. Notably, proposers for STIS and NICMOS should stay current as ground calibration and testing is finalized. An HST Data Handbook is available, describing the data that are produced by each of the current SIs; an updated version will be issued in 1997 to include STIS and NICMOS. In addition there are documents describing the HST data-analysis software (STSDAS) and the Synphot software for estimating instrument count rates and exposure times. For Archival Researchers a "primer" and a detailed manual are available which describe how to gain access to the HST data archive through StarView. There is also a catalog of the GO and GTO observing programs that have already been accepted, which is available electronically via STEIS (see Appendix B) and from the ST-ECF (see Appendix A and the "Archive" column in recent issues of the ST-ECF Newsletter for details). Proposers with no network access may obtain a hardcopy of this catalog from the STScI Help Desk.
The STScI supports a broad range of World-Wide Web (WWW) information pages which may be found under: http://www.stsci.edu/top.html. Of particular interest for proposing for HST observing time are the Instruments pages which provide access to electronic versions of the Instrument Handbooks, extensive technical documentation, a range of exposure time calculation tools, frequently asked questions, and late breaking news in the form of advisories.
It should be of particular interest for prospective users of STIS and NICMOS to peruse the applicable Web pages. Current documentation has of necessity been developed before much of the important ground testing for the new instruments. It is certainly the case that further information of interest to observers will become available between now and the Cycle 7 proposal deadlines. The STIS and NICMOS groups will in particular plan to provide substantial updates on the status of their instruments around mid-August 1996.
The entire documentation set is available in most institutional libraries as well as on the instrumentation pages of STEIS. Proposers are urged to use one of theses sources to decide which instruments will suit their scientific objectives. Proposers may then find it convenient to order personal copies of the manuals they will be using extensively. To order documentation, please fill out the form on the Phase I Web Documentation Server available at URL http://www.stsci.edu/proposer.html, or contact the STScI Help Desk.
Updates to the technical information contained in these documents are provided in the STScI Newsletter and also will be maintained and updated through the STEIS (Appendix B). Proposers should consult both of these sources for the latest updates when preparing their proposals.
In past cycles the CP mailing (to Libraries and a few thousand individuals!) included each updated version of the several Instrument Handbooks. With this mailing of the CP, in an effort to hold down costs, paper copies of the Instrument Handbooks will be mailed to individuals only upon request. At least three approaches may be pursued to determine whether a specific handbook is desired in paper form:
1) Brief instrument descriptions appear in §13 of this CP.
2) All of the Instrument Handbooks in Table 1(a) are available on-line with full HTML (i.e., user friendly) links. While for some purposes a paper copy is superior, some prospective proposers may prefer the easily accessed electronic versions.
3) The updates for WFPC2, FOC and the FGS Instrument Handbooks for Cycle 7 are non-trivial, but not major. To aid you in deciding whether to request a new paper copy we describe in Appendix E the primary changes made for the latest versions.
The Synphot software has now largely been superceeded by more user friendly Web tools for estimating instrument count rates and exposure times. These tools also provide warnings about rates that exceed any linearity or safety limits. All may be reached through the individual instrument pages.
3.1.1 Scope of GO Proposals
Observing proposals may request any scientifically justified amount of observing time. In Cycle 1 the Space Telescope Advisory Committee (STAC) advised that the best scientific use of the HST required a mix of programs of different sizes, with roughly comparable amounts of time going to programs with <10, 10-30, and >30 spacecraft hours. In recent cycles, increasing amounts of time have been devoted to smaller proposals. Prior to Cycle 7, a new STAC re-affirmed the general principle of a balance of program sizes and suggested a new category of proposal, the "Major Programs" (Appendix I).
Major Programs are those requiring . 100 orbits, and so should be strongly justified, well-thought-out proposals that constitute a clear advance in our understanding. The Telescope Allocation Committee (TAC) is expected to approve ~3 Major Programs in this cycle. Some Major Programs may request long-term status (see below), with additional orbits requested in Cycles 8 and 9.
Smaller proposals will be classified according to the number or orbits requested per cycle as either "small" (<30 orbits) or "medium" (30-99 orbits). The classification will be determined by the number of orbits requested in Cycle 7 (or for long-term proposals, the number of orbits in whichever Cycle requests the largest allocation). The TAC will give special consideration to "medium" proposals, with a view toward increasing the number of accepted medium-size programs.
3.1.2 Major Programs
A new initiative in Cycle 7 is the call for Major Programs. The STAC considered a number of ideas solicited from the community for programs that would require an effort and commitment of telescope time and related resources comparable to the original Key Projects. The diversity and large number of high-quality ideas led the STAC to recommend an expansion of the original concept. Specifically, the committee recommended that the community be encouraged to submit Major Program proposals requiring 100 or more orbits in one or more Cycles. Major Programs must address important scientific questions which can not be carried out in smaller time allocations and which utilize the unique capabilities of the HST. If scientifically justified, a Major Program may extend beyond the proposal Cycle subject only to review for progress. The Major Programs will be evaluated for scientific merit by the appropriate Peer Review Panels, and all will then be forwarded to the Telescope Allocation Committee (TAC). The TAC will decide the actual allocation of HST time, which will not be counted against any Panel's primary allotment.
The STAC was confident that at least three Major Programs would be ranked sufficiently highly to be awarded time in Cycle 7 and beyond and, in the steady state, approximately 10-20% of the GO time will be devoted to such programs. The STAC did not identify particular Major Program topics to be targeted, primarily because it did not wish to restrict the creativity of the community in formulating imaginative new projects. The STAC applauded the decision of the Cycle 1 TAC in not closing off competition in the areas of the Key Projects and strongly recommended continuation of this policy in connection with future Major Programs.
Selection of a Major Program for implementation does not rule out acceptance of smaller projects to do similar science, although target duplication and overall program balance will be considered.
3.1.3 Long-Term Programs and Continuation Proposals
GO programs will normally be completed within the current scheduling cycle. However, long-term programs (i.e., observing programs having a duration of more than one cycle) may also be accepted. Major Programs may be long-term programs.
Long-term programs also include projects that require a long time baseline, but not necessarily a large total number of spacecraft orbits, in order to achieve their scientific goals. Typical examples of such projects might be astrometric observations or long-term monitoring of variable stars or active galactic nuclei. Proposals for long-term status should be limited to cases where such status is clearly required to optimize the scientific return of the project. The scientific necessity for an allocation of time extending beyond Cycle 7 should be presented in detail.
Long-term programs may be approved for durations of up to three observing cycles. New long-term proposals should describe the entire requested program and should provide a cycle-by-cycle breakdown of the number of orbits requested. See Part III for details.
The Cycle 7 TAC can award limited amounts of time in Cycles 8 and 9, where the scientific justification is compelling, with no re-submission of proposals in those cycles. Note that this is a significant change from previous cycles. Continuation proposals in later cycles will be reviewed by STScI to verify adequate progress.
A Cycle 7 continuation proposal is required from GOs who wish to continue long-term programs for which Cycle 7 time was already tentatively approved in Cycle 5 or 6. If satisfactory progress is being made, and the need for continuing HST observations is justified, the Telescope Allocation Committee (TAC) may recommend that the program continue to receive observing time in Cycle 7. However, because of the large oversubscription of HST time, the TAC will consider the scientific importance of the continuation requests relative to newly proposed programs, and it may modify the proposed continuation program or, in some cases, not recommend further observations.
As noted in Part III, continuation proposals should provide summary information for the entire project, along with a cycle-by-cycle breakdown of the requested spacecraft orbits, including previously allocated time. However, the observation summary table in the proposal should specify only the visits for Cycle 7, not the proposed visits for future cycles nor those approved for past observing cycles.
3.1.4 Surveys and Scientifically Risky Proprosals
The STAC particularly urged support for two types of proposals, Survey Programs and Scientifically Risky Proposals, both of which will therefore be considered explicitly in the Cycle 7 review.
Survey Programs are those that, while well-justified with a clear scientific program, also produce large, uniform databases having significant archival value for a larger number of investigations. Proposers are advised that a commitment to waive part or all of the proprietary period will be considered positively in selecting such programs.
Scientifically Risky proposals are innovative and have the potential for considerable scientific payoff but have less than 100% probability of success. Note that these are altogether different than technically risky programs, which could endanger the safety of an instrument or of the spacecraft (e.g., observation of Mercury), and which therefore will not be considered for execution.
3.1.5 Target-of-Opportunity Proposals
Proposals will normally identify one or more specific astronomical objects (or "targets") that will be observed. However, it is possible to submit proposals to observe unpredictable transient phenomena (such as novae or supernovae, or newly discovered comets). For such proposals it may not be possible to include a list of specific objects; instead, the proposer may specify "generic targets" (see §17.1, Item #11). The proposal should present a detailed plan of observations that will be implemented if the specified event occurs; it should also provide an estimate of the probability of occurrence of the specified event during the 12-month observing cycle.
Because of the heavy impact that target-of-opportunity observations have on the short- and medium-term HST schedule, no more than 6 rapid (e.g., 2 weeks turnaround) target-of-opportunity programs will be awarded time in Cycle 7. No targets-of-opportunity will be given priority for execution during the first half of Cycle 7 and will, during this time, be accepted on a shared risk basis (see §1).
Target-of-opportunity proposals will be peer reviewed through the normal procedures. An accepted program will be executed only in the event that the specified phenomenon actually occurs, and it will be the responsibility of the GO to inform STScI of the occurrence of the phenomenon. If the event does not occur during the observing cycle, the program will be deactivated at the end of the cycle.
Accepted programs will require submission of a Phase II proposal before the event occurs. When notifying STScI of the appearance of the target of opportunity, the GO must provide an accurate target position. If there is uncertainty in the filter, exposure time, or other exposure parameters, the Phase II proposal should include a selection of preplanned contingencies from which the observer will make a selection.
A review of the completed proposal will be made to assure the safety of the observations, to verify that the program complies with the original observing-time allocation and scientific objectives, and to identify a breakpoint in the presently executing Science Mission Specification (SMS). After approval by the Director, the program will be entered into the scheduling system, the SMS will be re-planned to contain the new observations, and the commands will be generated to conduct the observations. The time necessary to conduct these activities will vary with the particular circumstances, but the minimum response time will be roughly 2-5 days, and this will be achievable only if all details of the proposal (except the target position) are available in advance. If the program requires submission of a new, detailed Phase II proposal, then the response time will be at least one week.
In the event of a sudden phenomenon of a nature that could not have been anticipated, for which it is felt that HST observations should be initiated on an urgent basis, a request for Director's Discretionary time may be submitted (see §3.4).
In the process of optimizing the HST observing schedule, the scheduling algorithm occasionally finds short time intervals during which it is impossible to schedule any exposures from the pool of accepted programs. In order to utilize these intervals for scientific observations, STScI has developed the capability to take short exposures ("snapshots") on objects selected from a large list of candidates.
Snapshot observations are placed on the schedule only after the observing sequence has been determined for the higher-priority targets. The gaps in the schedule that are appropriate for snapshot exposures are short-no more than a single target visibility period and frequently less than 20 minutes. In certain cases, the guide-star acquisition can be omitted for snapshot exposures, which will then be taken under gyroscopic control (tracking performance is described in §12.2). Past experience shows that there are 11 or 12 opportunities each week for snapshot exposures or about 600 per year.
Astronomers are invited to propose lists of candidate snapshot targets for Cycle 7. Snapshot proposals should provide a discussion of the target sample and the potential use of the data by the investigator and the astronomical community, specify the number of candidate targets in the sample, and provide a typical example of a snapshot exposure, including the instrument and mode, exposure time, filter, and required acquisition mode.
Snapshot proposals will be considered for all instruments. Proposers are advised that a commitment to waive part, or all, of the proprietary period will be included in the selection criteria for such programs. Snapshot proposers should consider the following guidelines:
Snapshot proposers should be aware that snapshot time allocations are not guaranteed; the number of observations actually executed will depend on the availability of appropriate schedule gaps. If a Snapshot exposure fails during execution it will not be repeated.
Completed HST observations, including both GO and GTO data, become available to the community upon expiration of their proprietary periods. The data are archived at STScI and are available for analysis by interested scientists through the HST Archival Research (AR) program. A copy of the HST archives is also maintained at the ST-ECF in Garching, to which European requests should normally be addressed. The Canadian Astronomy Data Centre (CADC) also maintains a copy of HST science data (only), and is the preferred source for Canadian astronomers. See §10 for an overview of the present contents of the archive, and for details of the procedures for accessing archival HST data.
Funding for U.S. astronomers to support the analysis of archival data is expected to be available during Cycle 7. Proposals for AR funding during Cycle 7 will be considered at the same time, and by the same reviewers, as proposals for GO observing time for Cycle 7, and the deadlines for submission of funded AR proposals are the same as for GO proposals. The review of AR proposals will be based on scientific merit and other appropriate criteria, as discussed in §7.2.3.
Proposals for funded Archival Research should be submitted on the special AR proposal form. The form should be submitted both in hardcopy (two copies) and by electronic mail. An electronic-plus-paper submission is required of all AR proposers. Detailed Budget Forms should be submitted with the paper copies of the Phase I proposal. Instructions for preparing AR proposals are given in §19. Each archival proposal should include an estimate of the total number of data sets that will be analyzed.
Scientific programs that require both funding for Archival Research and new observations should be submitted as two separate proposals, one requesting funding for the Archival Research, and the other proposing the new observations. The proposals should refer to each other so that the reviewers will be aware of both components of the proposed project.
Up to 5% of the available HST observing time may be reserved for Director's Discretionary (DD) allocation. A proposal for DD time might be appropriate in cases where a truly unexpected transient phenomenon occurs or when developments since the last proposal cycle make a time-critical observation necessary. Very few non-time-critical DD proposals are approved; in general, the proposers are encouraged to resubmit their proposals for the next peer-review cycle.
As discussed elsewhere in this document, the HST observing schedule is determined several weeks in advance of the actual observations. Although it is technically feasible to interrupt the schedule and initiate observations of a new target, short-notice interruptions place very severe demands on the planning and scheduling process and are therefore restricted. Hence, requests for DD time must be extremely well justified and, if at all possible, submitted at least three months before the date of the requested observations. In view of the long lead times, it will in many cases be more appropriate to submit a proposal through the normal GO procedures (e.g., as a target-of-opportunity program) than to request DD time.
Proprietary periods for DD programs will generally be shorter than the usual 12 months described in §6.2; especially in the case of an unexpected target of opportunity, the Director may make the data non-proprietary and available immediately to the astronomical community. However, DD proposers may request and justify longer proprietary periods in their proposals.
Scientists wishing to request DD time should do so by using the DD Submission Template on the World-Wide Web (WWW) at the following URL: http://www.stsci.edu/proposer.html. If you do not have access to a Web browser, then you may inquire about DD procedures from the STScI Help Desk.
The Director will usually seek advice on the scientific merit and technical feasibility of such requests from STScI staff or outside specialists before taking action. The primary criteria for acceptance is extremely high scientific merit, and a strong demonstration of the urgency of the observations.
The National Aeronautics and Space Administration (NASA) has awarded a portion of the observing time during the first three years of HST operations, following SM97, to scientists involved in the development of the new instruments. These scientists are the Guaranteed Time Observers (GTOs). Approximately 370 orbits, or 6.8% of the observing time during Cycle 7, will be assigned to the GTOs.
4.1.1 Overview
Primary observations are defined as those that determine the telescope pointing and orientation. Since all of the Scientific Instruments (SIs) are located at fixed positions in the telescope focal plane, it is possible simultaneously to observe with one or more instruments in addition to the primary instrument; those additional observations are named parallel observations (see §4.2).
Primary observations are scheduled at times that maximize scientific return and telescope efficiency and they have operational priority over parallel observations made with a second or third SI. In most cases the GO will not need to be present at STScI during the execution of the observations. However, special considerations regarding scheduling and execution of observations may come into play under the circumstances described below.
4.1.2 Time-Critical Observations
Proposals may request that HST observations be made at a specific date and time, or within a range of specific dates. Examples of time-critical observations for which such requests would be appropriate include, but are not limited to, the following: (1) astrometric observations; (2) observations of specific phases of binary or pulsating stars; (3) monitoring of variable stars or galactic nuclei; (4) imaging of surface features on rotating solar-system bodies; (5) observations that require a specific telescope orientation (since the orientation is fixed by the date of observation, as discussed in §11.2); (6) observations that must coincide with simultaneous ground-based or other space-based experiments; and (7) observations required to be repeated at some time interval.
Time-critical events that occur over short time intervals compared to the orbital period of HST (such as eclipses of very short-period binary stars) introduce an additional complication because it will not be known to sufficient accuracy, until a few weeks in advance, where HST will be in its orbit at the time of the event, and hence whether it will occur above or below the spacecraft's horizon. Proposals to observe such events can therefore be accepted only conditionally (see §14.3).
Because of the constraints that time-critical observations impose on the HST scheduling system, the scientific justification for such requests should be presented in detail in the observing proposal. Time critical observations with STIS or NICMOS for the first half of Cycle 7 (before 1998) will be accepted on a shared risk basis; they will be executed on a non-interference basis with ongoing efforts to bring full capabilities on-line as first priority, but will not be candidates for repeat or later scheduling should difficulties arise.
4.1.3 Real-Time Observations
A limited capability is available for real-time interactions during HST observing. Interactive target acquisitions (§15.2.2), small maneuvers without target acquisition, and real-time analysis for science purposes are permitted in real-time.
The usual purpose of a real-time interaction will be to carry out an interactive target acquisition, either with the same SI to be used for the scientific observations, or with a camera SI followed by an offset to the required SI (see the Instrument Handbooks for technical details). This type of pointing improvement is required when the target must be positioned more accurately than can be done with the guide stars alone (typically about 1"), and when there is no on-board mechanism available to accomplish that task, or when early acquisition techniques cannot be used. An example would be a target of opportunity proposal to observe a new supernova using a small FOC aperture: the target must be positioned to high accuracy to fall in the aperture, while the FOC has no onboard target acquisition capability, and the target is changing too rapidly to allow an early acquisition image to be made a week or two before the science observations will occur.
Small maneuvers without target acquisition are typically used to improve the telescope pointing without requiring an observation to measure the target location. The need for this type of improved pointing arises most often for solar-system targets, because of uncertainties in the target's ephemeris, and because the HST orbital decay causes changes in the times of observations after the planning and telescope scheduling have been completed. In general, the size of all real-time maneuvers is limited by the requirement that the same pair of guide stars be used to accomplish all such pointings.
Real-time analysis may be requested for either science data or engineering telemetry associated with an observation for other reasons than target acquisition. The scientific necessity of seeing the data immediately must be fully justified in the proposal.
Availability of the Tracking and Data Relay Satellite System and other constraints limit the number of real-time interactions to a few per week. Real-time observations generally require additional operational overheads, and thus reduce observing efficiency. However, some scientific programs require this activity for success and it should be requested for them. In those cases, the scientific and operational justification for such interactions should be presented clearly in the observing proposal because real-time interactions are a limited resource.
Real-time observations (see also §15.2.2) will generally require the GO's presence at STScI during the exposures. The GO will make a maneuver decision based on evaluation of the data transmitted to the ground, and the appropriate command request will be sent through the control center at the Goddard Space Flight Center to the HST. STScI personnel will be present to assist the GO, and to execute the command requests.
Parallel observations provide a mechanism for increasing the productivity of the HST observatory. Parallel observations are observations made with one or more additional SIs while another SI is carrying out a primary observation. An essential difference between primary and parallel observations is that the latter are made solely on a basis of non-interference with the associated primary observations.
Since each SI samples a different portion of the HST focal plane (see Fig. 2, §13.6), an SI used in parallel mode will normally be pointing at a "random" area of sky several minutes of arc away from the primary target. Thus parallel observations are usually of a survey nature. However, many HST targets lie within extended objects such as star clusters or galaxies, making it possible to conduct parallel observations of nearby portions of, or even specific targets within, these objects.
Parallel observations of the following types may be proposed:
1. Pure parallel observations. In this case, a proposal is submitted for parallel observations that are unrelated to any specific primary observations. Proposals for such programs may involve either specific or generic targets; however, the latter are more common. Appropriate scheduling opportunities for such observations will be identified by STScI.
2. Coordinated parallel observations. In this case, the GO requests use of two or more SIs simultaneously, typically in order to observe several adjacent targets or regions within an extended object. Proposals for coordinated parallel observations should present a description of a coherent scientific program that clearly requires simultaneous usage of two SIs.
Some examples of possible parallel programs may clarify these concepts:
1. A proposal could be submitted that would call for a WFPC2 frame to be obtained whenever one of the other SIs is carrying out an observation at a galactic latitude |b| > 45. .The aim of such a program might be to carry out star counts at faint magnitudes, or to search for distant QSOs or galaxies. This is an example of pure parallel observations.
2. A proposal could request that a WFPC2 image be obtained whenever another SI is observing any target in a region centered on a specific position (such as that of M87 or NGC 4565). Here the aim might be to conduct a survey of the globular clusters surrounding the galaxy, or to search for luminous stars or H II regions. Such a proposal could be submitted either as a pure parallel program (on the plausible assumption that other GOs will submit successful proposals to observe these galaxies with HST), or as a coordinated parallel program (if the GO were planning other kinds of observations of the same galaxies).
Technical discussions of parallel observations are given in the Instrument Handbooks. The effective aperture locations are listed in Table 4 and shown in Figure 2 (§13.6).
Parallel observations are not permitted to interfere significantly with primary observations; this restriction applies both to concurrent and subsequent observations. Some examples of this policy are the following:
The WFPC2, STIS, NICMOS, and FGS may all be used for pure parallel programs in any combination of primary and parallel instruments. The FOC f/96 camera and the STIS MAMAs may be used together with any other instrument for coordinated parallel observations (within the same proposal), but not for pure parallel observations. In addition, no pure parallel observations are allowed in Cycle 7 with the STIS CCD in the 50CCD clear aperture configuration (see the STIS Instrument Handbook for details).
The spacecraft computers automatically correct the telescope pointing of the primary observing aperture for the effect of differential velocity aberration. This means that image shifts at the parallel aperture of 10 to 20 mas can occur during parallel exposures. The effect of the shift can be minimized for coordinated parallel observations by using the SI with the lower spatial resolution for the parallel exposure.
Proposals for HST observing time may be submitted by scientists of any nationality or affiliation, and may request use of any of the SIs. Each proposal must identify a single individual who will act as Principal Investigator (PI), but should also list all Co-Investigators (Co-Is) who will be involved in the analysis of the data. The PI will be responsible for the scientific and administrative conduct of the project, and will be the formal contact for all communications with STScI. All proposals will be reviewed without regard to the nationalities or affiliations of the proposers.
An agreement between NASA and the European Space Agency (ESA) states that a minimum of 15% of HST observing time (on average over the lifetime of the HST project) will be allocated to scientists from ESA member states. It is anticipated that this requirement will continue to be satisfied via the normal selection process, as it has been in previous cycles. In order to monitor the allocation to scientists from ESA member states, STScI requests that each PI and Co-I whose affiliation is with an ESA member-state institution be identified as such in the list of investigators contained in the proposal.
Proposals for funded Archival Research may be submitted only by scientists affiliated with U.S. institutions. Similarly, only U.S. scientists may request funding from STScI for GO programs. See §3.3 and Appendix C for details.
Endorsement signatures are not required for Phase I observing proposals (unless required by the regulations of the proposing institution); such endorsements will be requested in Phase II from successful GOs only.
However, endorsement signatures (those of the PI and of an authorized institutional official) are required for funded Archival Research proposals, due to the required inclusion of Budget Forms.
Proposals for observing time from student PIs will be considered. Each such proposal should be accompanied by a written statement from the student's faculty advisor certifying (1) that the student is qualified to conduct the observing program and data analysis; and (2) that the student is in good academic standing. If the research is part of a doctoral thesis, the proposal should so indicate. (The faculty advisor's statement is not required in cases where a student is listed in the proposal only as a Co-I.) Students should, however, be particularly aware of the inherent uncertainties of space-based research and of the possible impact of delays upon their educational progress.
Subject to availability of funds from NASA, STScI will provide financial support for U.S. observers and U.S. Archival Researchers only. Detailed policies that apply to such funding are discussed in Appendix C of this document. ARs wishing to apply for such support should submit Budget Forms, as described above and in §19. Successful GOs will be requested to provide the Budget Forms as part of their Phase II submissions.
For successful observing proposals submitted by non-U.S. PIs with U.S. Co-Is who request funding, one of the U.S. Co-Is should be designated as administratively responsible for the STScI funding, and should collect and submit the budget forms for all of the U.S. Co-Is in Phase II.
Proposers from ESA member states should note that ESA does not fund HST research programs. Therefore, successful ESA member-state proposers should seek any necessary resources from their respective home institutions or national funding agencies. ESA observers do, however, have access to the data-analysis facilities and technical support of the staff of the ST-ECF (see Appendix A).
Proposals submitted to STScI will be kept confidential to the maximum extent consistent with the review process described below. However, all Phase II information for accepted programs will be publicly accessible, including PI and Co-I names, project titles, abstracts, description of observations, special scheduling requirements, and details of all targets and exposures.
This subsection discusses several aspects of observations that may duplicate observations that have already been obtained with HST, or are currently in the pool of accepted HST programs. An observation is defined as duplicating a previous one if it is on the same astronomical target or field, with the same or similar instrument, a similar instrument mode, and a similar spectral range. It is the responsibility of proposers to check their proposed observations against the catalog of previously executed or accepted programs (see below), and, if any duplications exist, to identify and justify them in the Phase I proposal.
Under NASA policy, the GTO programs (see §3.5) are protected against contemporaneous acquisition by the GOs of duplicate observations. Proposed GO observations that are judged to infringe upon this protection will be disallowed. However, the duplication protection is as specifically defined above; entire classes of objects or broad scientific programs are not protected. The GTOs are entitled to revise their programs after each cycle of GO selection, but they in turn may not duplicate the previously approved GO programs. The protection of each observation is in force throughout its proprietary data-rights period (see §6.2), and then expires.
A catalog of all past and planned GO and GTO observing programs is available by anonymous ftp from STEIS (Appendix B), or it can be examined interactively using StarView (Appendix H); most proposers will find StarView the easier and more productive method. This catalog consists of two parts: a list of exposures, and the scientific abstracts for each program.
Prospective GOs should examine the catalog and exposure lists carefully before submitting their proposals, to ensure that they have not duplicated these programs. If there are duplications, they must be identified and justified strongly as meeting significantly different and compelling scientific objectives. Without specific TAC recommendation to retain such exposures, STScI will remove or restrict them during the duplication checks that are made in Phase II (§8).
Snapshot targets may not duplicate approved GO or GTO programs. Following selection, investigators will define the target samples and may be called upon to assist in the elimination of target duplications.
It may occasionally happen that a proposer requests an acquisition image that is already contained in a GTO program, which would be protected according to the NASA policies outlined above; if an early-acquisition image is determined to be in conflict with a protected GTO image, the GO-requested image may still be permitted, but may only be used for acquisition purposes.
GOs and GTOs have exclusive access to their scientific data during a proprietary period. Normally this period is the 12 months following the date on which the data, for each target, are archived and made available to the investigator after routine data processing (§9.1). At the end of the proprietary period, data are available for analysis by any interested scientist through the HST archive (see §3.3 and §10).
Proprietary periods longer than 12 months may occasionally be appropriate for long-term programs (defined in §3.1.3 as programs whose observations extend over more than one cycle) if there is a need to have most or all of the data available before any significant scientific results can be obtained. Requests for data-rights extensions beyond 12 months should be made in the original observing proposal, and will be subject to the initial TAC review.
Proposers who wish to request a proprietary period shorter than one year, or to waive their proprietary rights, are welcome to so specify in their proposals. Because of the potential benefit to the community at large, particularly in the case of large projects, proposers are asked to give this possibility serious consideration whenever they feel that such waivers would not be harmful to their programs.
It should be noted that certain technical information about observations, including for example data-quality assessments, will be collected when observations are made and will be included in the archival database.
Parallel observations are an efficient way of utilizing HST and in Cycle 7 we expect to be able to operate FOC, WFPC2, STIS, and NICMOS together in parallel. As an example, multi-orbit spectroscopic observations when STIS is prime will provide numerous opportunities for deep-sky imaging with both WFPC2 and NICMOS in parallel. Accordingly, we encourage proposers to submit pure-parallel programs or to consider coordinated parallel observations in their Phase I proposals. We expect parallel time to be oversubscribed in Cycle 7. Thus, requests for coordinated parallels should be explicitly justified in the Phase I proposal. For parallel observing with NICMOS all three cameras should always be used (see §13.3 on NICMOS below).
Observations of targets that lie in the CVZ (defined in §14.1) have been shown to be more than a factor of two more efficient than the ensemble of non-CVZ observations; hence observers are encouraged to use the CVZ when possible, in order to maximize the scientific return and efficiency of their observations. The allocation of spacecraft orbits allows proposers to evaluate straightforwardly the efficiency gains realized through observations made in the CVZ. It will often be found that use of the CVZ will allow a significant increase in the exposure time possible during a given number of spacecraft orbits, and hence its exploitation is to the proposer's advantage. Note however, that the CVZ is considered to be a limited resource. If TAC approval for use of the CVZ is not obtained, it will not be possible to require CVZ observations in Phase II. Therefore requests for the CVZ must be made and justified in the Phase I proposal. Proposers should also be aware that it is not possible to use the SHADOW TIME and LOW SKY special requirements in the CVZ, and that special timing requirements are not generally compatible with CVZ observations. Hence, observations requiring low background should not be proposed for execution in the CVZ (see §18.2).
A detailed examination of all the observing constraints has shown that there are two distinct CVZ regions (see Appendix J)-the heart and the wings. The "heart" of the CVZ are those positions where at least two scheduling opportunities exist which are each at least twice as long as the requested visit. These observations will be treated as any other observation; i.e., STScI will make a reasonable effort to implement the program with the total implied visibility time. This includes implementing the program with a larger number of non-CVZ orbits, if scheduling in the CVZ is not obtainable.
The "wings" of the CVZ are those positions where limited scheduling opportunities exist. Often, it is possible to schedule such observations in the CVZ. However, it is possible that conflicts in scheduling will make it impossible to schedule such programs during these limited opportunities. For these declination ranges the proposer must choose from two options:
1. Propose observations with the explicit assumption of 96 minutes per orbit in Phase I. If approved, in Phase II your proposal must then include the CVZ special requirement. If we are not able to schedule the observations in CVZ, then depending on feasiblity and the TAC recomendation, the observations may be dropped entirely or scheduled with the same number of non-CVZ orbits, i.e., the total visibility time is reduced by approximately half. The proposer must decide whether the competitive advantage of assuming CVZ for a proposal is worth the risk of the schedule not supporting the CVZ window.
2. Use the standard orbit visibility (Table 7 in §18.2). The observation might still be executed while in the CVZ for reasons of overall efficiency but the time saved cannot be added to the observations.
Successful proposers should be aware that the actual execution of their observations may, in some cases, prove impossible. Possible reasons include the following: (1) the accepted observation could be found technically extremely difficult or infeasible only after receipt of the Phase II information; (2) the observing mode or instrument selected may not be operational; (3) it might be found that suitable guide stars do not exist; or (4) the total amount of HST observing time in the cycle actually available could prove to be less than assumed. Therefore, all observations are accepted for the HST program with the understanding that there can be no guarantee that the observations will actually be obtained. Target-of-opportunity and parallel programs can be particularly complex to plan and execute, and will be completed only to the extent that circumstances allow. Proposers should contact the STScI Help Desk if they have questions about whether an observation is feasible.
The Instrument Handbooks contain details on the standard calibrations. Any special calibration needs not met by the advertised standard calibration program are the responsibility of the proposer and will require a direct request for additional observing time in the Phase I submission. Proposers are encouraged to contact the STScI Help Desk to obtain information on calibration of specific SIs, especially if they have demanding calibration requirements that may go beyond standard levels.
Data flagged as having been acquired for calibration purposes will normally be made non-proprietary. All HST data may be accessed and analyzed by appropriate Instrument Scientists to assess instrument performance and to develop calibrations. If proprietary data is used in this way strict confidentiality is maintained.
It is expected that the results of HST observations and Archival Research will be published in the scientific literature. All publications based on HST data must carry the following footnote (with the phrase in brackets included in the case of Archival Research):
"Based on observations made with the NASA/ESA Hubble Space Telescope, obtained [from the data archive] at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555."
If the research was supported by a grant from STScI, the publication should also carry the following acknowledgment at the end of the text:
"Support for this work was provided by NASA through grant number [###] from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555."
One preprint or reprint of each refereed publication based on HST research must be sent to the following address:
Librarian
Space Telescope Science Institute
3700 San Martin Dr.
Baltimore, MD 21218 USA
In addition, one preprint of each publication based on HST research should be sent to the following address:
Dr. David Leckrone
HST Senior Scientist
Code 440
Goddard Space Flight Center
Greenbelt, MD 20771 USA
This advance information is important for planning and evaluation of the scientific operation of the HST mission. We also remind HST observers that they have a responsibility to share interesting results of their HST investigations with the public at large. The Office of Public Outreach of the STScI is available to help observers use their HST data for public information and education purposes.
The review of proposals for use of the Hubble Space Telescope (HST) is carried out in two phases, which are managed by the Space Telescope Science Institute (STScI). In Phase I, proposers submit a scientific justification and observation summary for review by the Telescope Allocation Committee (TAC). The TAC review results in a list of projects that are recommended to the STScI Director for preliminary approval and implementation. During Phase II, the General Observers (GOs) whose projects have been recommended provide complete details of their proposed observations, to allow the STScI to conduct a full technical feasibility review of the programs. Also in Phase II, a cross-proposal exposure duplication test searches for similar exposures among previous and current HST programs. Up-to-date Exposure Catalogs are made available to proposers prior to the proposal deadline (Phase I) in order to avoid duplication-related problems during the Phase II implementation and review. Upon final approval by the Director, the Phase II information is then used to schedule and obtain the actual observations.
"Phase I" refers to the process from proposal preparation and submission through the selection of a recommended list of accepted programs by the peer reviewers and the Director's approval. "Phase II" (see §8) refers to the detailed program preparations (including specifications of the actual HST exposures in complete detail) that are subsequently carried out by the GOs who have been approved for observing time.
The first step in the evaluation of a proposal is its technical review by STScI. This is carried out by a careful reading of the proposal by an STScI staff member. Any technical or feasibility problems that become apparent will be brought to the attention of the peer reviewers.
Any cases of GTO duplication (which are not allowed according to the policy discussed in §6.1) that may come to the attention of the peer reviewers could lead to rejection during the Phase I deliberations. A final systematic computer-aided check for duplications of previous GTO observations is carried out in Phase II.
Since a portion of the proposal processing will be accomplished by computer, it is essential that the proposal forms and electronic files be filled out in accordance with the instructions given in Part III.
The evaluation of the scientific merit of proposals is accomplished via a two-stage peer-review process, which is managed by the STScI. Proposals are ranked according to a well-defined set of criteria (§7.2.3) by scientists chosen from the international astronomical community, in order that a final recommended HST program may be transmitted to the STScI Director.
7.2.1 Subdiscipline Review Panels
In the first stage of the scientific review, each proposal will be considered in detail by the appropriate expert panel. The outcome of the panels' deliberations will be recommended allocations of spacecraft orbits (for observing proposals) or funding levels (for AR proposals), and ranked lists of proposals.
7.2.2 Telescope Allocation Committee
The final recommended GO and AR programs will be selected from the ranked lists by the Telescope Allocation Committee (TAC), which will be composed of the chairpersons of the review panels plus additional interdisciplinary scientists who were not members of individual panels.
The aim of the TAC will be to integrate the panel recommendations into a balanced overall scientific program for HST. The TAC will explicitly consider all major Programs (§3.1.2), all highly recommended requests for long term allocations (§3.1.3), and those highly ranked proposals of the Survey, Risky (§3.1.4), or medium (§3.1.1) categories.
7.2.3 Selection Criteria
The review panels and TAC will base their evaluations of HST observing proposals (and, where appropriate, AR proposals) on the following criteria:
In the evaluation of proposals to conduct Major Programs, the panels and TAC will use the following additional criteria:
The TAC will make its recommendations to the STScI Director, who will make the final allocation of observing time. The time recommended by the TAC and approved by the Director will be in units of "orbits." Directions and worksheets for calculating the required number of orbits are given in §18 and Appendix K; they take into account the actual on-target exposure time, plus the overhead time spent acquiring guide stars and placing the targets in the desired instrument apertures, reacquiring guide stars after Earth occultation, preparing the instruments for the observations, and reading out the data.
All proposers will receive written (both electronic and paper) notification of the outcome of the selection process. It is anticipated that the panels and TAC will meet approximately two months after the proposal submission deadline, and that the written notifications of the Phase I outcome will be sent shortly thereafter. Archival proposers are also informed at this time of the outcome of review of their submitted budgets.
For complex or difficult programs, STScI encourages observers to visit STScI before the Phase II deadline. U.S. GOs may incur pre-award travel costs to support such visits, and financial support for such visits, where appropriate, may be included in the Phase II budget and in a preparatory funding request. However, it should be noted that all pre-award expenditures are incurred at the risk of the PI and that all funding is contingent upon the availability of funds from NASA at the time the award is made. GOs are notified the results of review of their submitted Phase II budgets approximately 3 months after the Phase II deadline.
Scientific data are routed from HST to the Tracking and Data Relay Satellite System (TDRSS), through the TDRSS ground station at White Sands, New Mexico, to the Data Distribution Facility (DDF) at Goddard Space Flight Center in Greenbelt, Maryland, and finally to STScI. At STScI the production pipeline of the Observation Support/Post Observation Data Processing Unified System (OPUS) provides standard processing for data editing, calibration, and product generation. These functions, performed automatically, include the following:
One tape copy (usually 8 mm Exabyte) of the raw and processed data is made and sent to the PI or his/her designee. Any further processing or scientific analysis is the responsibility of the GO. The raw and calibrated data are also stored in the Hubble Data Archive, where they become available to other researchers after expiration of the proprietary period.
As described below, STScI provides assistance with data analysis and archive access, either by e-mail or telephone, or during GO visits to Baltimore.
The Space Telescope Science Data Analysis System (STSDAS) is a set of tools and support software used to calibrate and analyze HST data. A companion package, TABLES, is a set of tools for creating and manipulating tabular data, reading and writing FITS images and tables, and creating customized graphics. STSDAS and TABLES are layered onto the Image Reduction and Analysis Facility (IRAF) software from the National Optical Astronomy Observatories (NOAO); one must be running IRAF in order to run STSDAS and TABLES.
STSDAS and TABLES are portable, and because they are layered onto IRAF, should run on any system for which an IRAF port exists. STScI, in conjunction with NOAO, actively supports STSDAS and TABLES on Sun workststions and file servers running SunOS and Solaris, DEC Alpha and VAX systems running OpenVMS and OSF-1, x86 PCs running Linux, Decstations running Ultrix, and HP, SGI, and IBM RISC workstations. The current version of IRAF varies with platform and can be found in the IRAF Web pages at http://iraf.noao.edu. Information on the most recent version of IRAF for OpenVMS may be requested from help@stsci.edu; STScI will be responsible for porting the next version of IRAF (V2.11) to OpenVMS.
STSDAS and TABLES provide a large range of data-analysis tools, including the following:
The STSDAS calibration software is the same as used in the OPUS pipeline. HST observers can, therefore, recalibrate their data, examine intermediate calibration steps, and re-run the pipeline using different calibration switch settings and reference data. STSDAS includes the software needed to generate new versions of calibration reference data and calibration parameters. STSDAS also provides tools for on-site users to access the Calibration Data Base and the data archive.
Observers should use up-to-date software, especially if it is used for analysis of positions from HST imaging data. Current software is backward compatible with all HST archival data. However, use of software with old release dates (e.g., pre-1994 for analysis of WFPC2 data) could return spurious results. The current release of STSDAS (version 1.3.4) is available for downloading from STEIS (see Appendix B), or it may be obtained on magnetic tape through a request to help@stsci.edu. Further information is contained in the STSDAS User's Guide, available from the STScI as described in §2.1. Questions about STSDAS may be addressed to help@stsci.edu.
A comprehensive guide to HST data products and data analysis, the HST Data Handbook, is available (see §2.1). Each selected observing program will be assigned an STScI Contact Scientist who is an Instrument Scientist for the primary instrument used in the program. Instrument Scientists have detailed knowledge of calibration and data analysis issues and will serve as the responsible single point of contact for technical help with any phase of data analysis. In addition, data analysis questions may be referred to the STScI Help Desk.
It is strongly recommended that new GOs (and experienced GOs who may be confronting complicated new data-analysis issues) plan at least one 1-2 week post-observation visit to STScI for the purpose of learning how to work with their data.
All science and calibration data, along with a large fraction of the engineering data, are placed in the Hubble Data Archive. As of May 1996, the archive contained approximately 2.5 Tbytes of data, comprising over 718,000 individual datasets. About 2 Gbytes of new data are archived each day. Over half the archive is science data, with over 100,000 datasets covering more than 9,500 different targets.
Most of the data in the archive are public and may be retrieved by any user. The data in the archive currently comprise about 31,600 WFPC2 images, 16,000 WF/PC images, 5,500 FOC images, 19,800 FOS spectra, 20,300 GHRS spectra, and 5,100 HSP scans.
The Hubble Data Archive is the hardware and software system by which HST data are stored. The heart of the archive is a system known as the Data Archive and Distribution Service (DADS).
STScI maintains Sun (archive.stsci.edu) and VMS (stdata.stsci.edu) host machines for users who want to work with the archive. Users should telnet to either computer and log in as guest with a password of archive. Guest users are able to browse the archive catalog and preview public data using the software interface StarView (see Appendix H), and retrieve documentation about the archive. Guest users cannot retrieve data from the archive, but they may use the guest account to become registered users by issuing the command register at the command line on either computer.
Registered users are assigned archive passwords, which allow them to retrieve data from the archive using the StarView user interface. The HST Archive Primer, which may be obtained as described in §2, contains details of how to run either the CRT or X-windows version of StarView, though most users should be able to get started just from the hints they will get when they log onto one of the host machines. Users logging in from a workstation or an X-terminal will most likely want to use "xstarview," because it allows one to preview the data before deciding whether to retrieve it. Both the CRT and X-windows versions of StarView allow one to search for HST observations based on any SIMBAD- (Set of Identifications, Measurements, and Bibliography for Astronomical Data) or NED- (NASA/IPAC Extragalactic Database) recognized target name.
Another way to find out what is in the HST archive is the Archived Exposures Catalog (AEC). This is a flat ASCII file that can be downloaded from STEIS, or from the archive or stdata computers. The AEC contains summary information about exposures, including the target name, position, instrument mode, and the date on which the data became (or will become) public. The AEC is updated monthly. The AEC is a text file that may be examined with any text editor. StarView is complete, accurate and up-to-the-minute, providing more detailed information about observations, allowing one to search for many observations simultaneously using selected keyword criteria, and allowing one to preview public HST images and spectra.
STScI maintains an "archive hotseat" (archive@stsci.edu or 410-338-4547) which operates during normal office hours. Any archive-related problems should be referred to the hotseat.
Several mechanisms are provided for Archival Researchers (ARs) to retrieve data. By logging into the archive or stdata computers and using StarView, registered users can retrieve archival data directly. One retrieves the data to one of the archive host machines, and then uses ftp to transfer the data to one's home machine. In addition, DADS can ship data, including proprietary data, directly to the user's home computer.
Network bandwidth limitations limit the amount of data that realistically can be transferred electronically. ARs may submit requests for large amounts of public HST data to be written to 8 mm Exabyte tape and shipped to them. Such requests may be submitted using StarView, or alternatively by completing the "Request for Archival Data" form, which is maintained as a PostScript file on the archive host machines. (The form can also be obtained by sending e-mail to the archive hotseat.) Unfunded researchers may submit requests for up to 20 Gbytes of data. Larger amounts will be provided to funded ARs, as outlined in their proposals.
STScI can provide limited assistance in the reduction and analysis of archival data, and encourages ARs to visit the Institute. Each funded AR program will be assigned an STScI staff contact from among the Contact Scientists; this individual will serve as a single point of contact to help resolve calibration and data analysis issues. In addition, the archive hotseat will attempt to resolve any problems encountered in using StarView, and can provide advice on strategies for conducting searches of the archive. However, proposers should plan to conduct the bulk of their Archival Research at their home institutions, and should request funding accordingly. Limited resources preclude extensive assistance in the reduction and analysis of data obtained by non-funded ARs.
As shown in Fig. 1, HST's Scientific Instruments (SIs) are mounted in bays behind the primary mirror. The Wide Field Planetary Camera 2 occupies one of the radial bays, with an attached 45 degree pickoff mirror that allows it to receive the on-axis beam. Three SIs (Faint Object Camera, Near Infrared Camera and Multi-Object Spectrometer, and Space Telescope Imaging Spectrograph) are mounted in the axial bays and receive images several arcminutes off-axis.
Figure 1: The Hubble Space Telescope
Major components are labelled, and definitions of V1,V2,V3 spacecraft axes are indicated.
During the servicing mission in December 1993, the astronauts installed the Corrective Optics Space Telescope Axial Replacement (COSTAR) in the fourth axial bay (in place of the High Speed Photometer). COSTAR deployed corrective reflecting optics in the optical paths in front of the Faint Object Camera, thus removing the effects of the primary mirror's spherical aberration. In addition the Wide Field and Planetary Camera (WF/PC) was replaced by the WFPC2, which contains internal optics to correct the spherical aberration.
The Fine Guidance Sensors (FGSs) occupy the other three radial bays and receive light 10-14 arcminutes off-axis. Since at most two FGSs are required to guide the telescope, it is possible to conduct astrometric observations with a third FGS. Their performance is unaffected by the installation of COSTAR.
For an overview of the SIs, see §13. Detailed information about each SI is contained in separate Instrument Handbooks (see §2.1).
HST receives electrical power from two solar arrays (see Fig. 1), which are turned (and the spacecraft rolled about its optical axis) so that the panels face the incident sunlight. During the 1993 servicing mission the astronauts installed new solar arrays, which have significantly reduced the thermally induced vibrations that the old arrays had been producing. Nickel-hydrogen batteries provide power during orbital night. The two high-gain antennas shown in Fig. 1 provide communications with the ground (via the Tracking and Data Relay Satellite System). Power, control, and communications functions are carried out by the Support Systems Module (SSM), which encircles the primary mirror.
In addition to STIS and NICMOS, the second servicing mission will replace several additional pieces of equipment. One of the FGSs (most likely FGS 2) will be replaced. The new FGS will have an adjustable fold flat to recover some of the performance capability lost by spherical aberration. A spare magnetic tape recorder will replace the failed ESTR-2. A solid state recorder (SSR) will replace ESTR-1, and will provide for a factor of 10 greater on-board data storage volume. This extra storage will be necessary to support parallel operations of the WFPC2, STIS, and NICMOS. It will also provide increased flexibility in scheduling HST observations, reducing the tight coupling with the TDRSS system.
HST is, in principle, free to roll about its optical axis. However, this freedom is limited by the need to keep sunlight shining on the solar arrays, and by a thermal design that assumes that the Sun always heats the same side of the telescope.
To discuss HST pointing, it is useful to define a coordinate system that is fixed to the telescope. This system consists of three orthogonal axes: V1, V2, and V3. V1 lies along the optical axis, V2 is parallel to the solar-array rotation axis, and V3 is perpendicular to the solar-array axis (see Fig. 1). Power and thermal constraints are satisfied when the telescope is oriented such that the Sun is in the half-plane defined by the +V1 axis and the positive V3 axis. The orientation that optimizes the solar-array positioning with respect to the Sun is called the "nominal orientation."
It should be noted that the nominal orientation angle required for a particular observation depends on the location of the target and the date of the observation. Observations of the same target made at different times will, in general, be made at different orientations.
Some departures from nominal orientation are permitted during HST observing (e.g., if a specific orientation is required at a specific date, or if the same orientation is required for observations made at different times). Roll is defined as the angle about the V1 axis between a given orientation and nominal orientation. Off-nominal rolls are restricted to approximately 5 degrees when the sun angle is between 50 degrees and 90 degrees, < 30 degrees when the sun angle is between 90 degrees and 178 degrees and is unlimited at anti-sun pointings of 178 degrees to 180 degrees.
HST utilizes electrically driven reaction wheels to perform all maneuvering required for guide-star acquisition and pointing control. A separate set of rate gyroscopes is used to provide attitude information to the pointing control system. The servicing mission restored or replaced three gyros that had failed since the original launch, so that the spacecraft currently has a total of six operational gyros. Any three of these are the minimum required for telescope pointing control.
The slew rate is limited to approximately 6 degrees per minute of time. Thus, about one hour is needed to go full circle in pitch, yaw, or roll. Upon arrival at a new target, up to 9 additional minutes must be allowed for the FGSs to acquire a new pair of guide stars. As a result, large maneuvers are costly in time and are generally scheduled for periods of Earth occultation or crossing of the South Atlantic Anomaly (see §14.2).
The telescope does not generally observe targets within 50 degrees of the Sun, 15.5 degrees of any illuminated portion of the Earth, 7.6 degrees of the dark limb of the Earth, nor 9 degrees of the Moon. Following the first servicing mission, the telescope is again allowed to point directly away from the Sun.
There are exceptions to these rules for HST pointing in certain cases. For instance, the bright Earth is a useful flat-field calibration source. However, there are onboard safety features that cannot be overridden. The most important of these is that the aperture door shown in Fig. 1 will close automatically whenever HST is pointed within 20 degrees of the Sun, in order to prevent direct sunlight from reaching the optics and focal plane.
Objects in the inner solar system, such as Venus or comets near perihelion, are unfortunately difficult or impossible to observe with HST, because of the 50 degree solar limit. When the scientific justification is compelling, observations of Venus and time-critical observations of other solar-system objects lying between 45 degrees and 50 degrees of the Sun may be carried out (this capability was successfully demonstrated in Cycle 4).
The HST observing schedule is constructed at STScI and forwarded to the Goddard Space Flight Center (GSFC) in Greenbelt, Maryland. The HST is controlled from the Space Telescope Operations Control Center (STOCC), located at GSFC. Communication with the spacecraft is via the Tracking and Data Relay Satellite System (TDRSS), which consists of a set of satellites in geosynchronous orbit.
Commands to HST originate at the STOCC and are sent via land-line or communications satellites to the TDRSS ground station at White Sands. From there the commands are sent via the appropriate TDRSS to HST. Scientific data are sent from HST to the STOCC via the reverse path, and then from the STOCC to the STScI via dedicated high-speed links.
The TDRSS network supports many spacecraft in addition to HST. Therefore, use of the network, either to send commands or return data, must be scheduled. Because of limited TDRSS availability, command sequences for HST observations are normally uplinked periodically and stored in the onboard computers. HST then executes the observations automatically.
It is possible for observers at STScI to interact in real-time with HST for specific purposes, such as certain target acquisitions. In practice, real-time interactions are difficult to schedule (see §4.1.3). Historically, during normal operations, fewer than 50 real-time interactions have been required per year.
HST currently uses two onboard tape recorders to store scientific data. After the second servicing mission a much larger capacity Solid State Recorder will be available. Except when real-time access is required, most HST observations are stored to a recorder and read back to the ground several hours later. There are, however, limits to the amount of data that can be handled by the ground system supporting HST. Some scientific programs requiring very high data-acquisition rates cannot be accommodated, because the SIs would generate more data than either the links or ground system could handle.
Because the primary mirror has about one-half wave of spherical aberration, the Optical Telescope Assembly (OTA) did not achieve its design performance until after the December 1993 servicing mission. Table 2 gives a summary of the excellent optical performance now being achieved.
Table 2: HST Optical Characteristics and Performance
[1] Expected performance.
Software has been developed at STScI for detailed simulations of HST images, which agree well with actually observed (pre- and post-repair) images. This Telescope Image Modelling (TIM) software, with its point-spread-function (PSF) library, is available for downloading from STEIS. Another set of software specifically designed to simulate HST camera images, called TINYTIM, is also available.
A figure showing actual measurements of the PSF and encircled energy achieved with the Faint Object Camera can be found in the FOC Instrument Handbook.
HST's Pointing Control System (PCS) has two principal hardware components. Rate gyros are the guidance sensors for large maneuvers and high-frequency (> 1 Hz) pointing control. At lower frequencies, the optical Fine Guidance Sensors (FGSs) provide for pointing stability, as well as for precision maneuvers such as moving-target tracking and offsets and spatial scans.
Each of the three FGSs covers a 90 degree sector in the outer portion of the HST field of view (FOV), as shown in Fig. 2 (§13.6). Optics within the FGS, using precision motor-encoder combinations, select a 5" x 5" region of sky into an x, y interferometer system. Once an FGS is locked onto a star, the motor-encoders are driven to track the interference fringe of the guide star. The encoder positions are used by the PCS software to update the current telescope attitude and correct the pointing.
The FGSs have two guiding modes: Fine Lock and Coarse Track. Fine Lock was designed to keep telescope jitter below 0.007" rms. Previously, there were periods of 2 to 5 minutes each orbit when there was increased jitter (0.020-0.050") due to thermal effects in the Solar Arrays. The combination of the new Solar Arrays and tuning of the pointing control system has successfully eliminated these effects. The telescope jitter is now routinely below the 0.007" rms level. A drift of up to 0.05" may occur over a timescale of 12 hours and is attributed to thermal effects as the spacecraft and FGSs are heated or cooled. Observers planning extended observations in 3 0.1" STIS slits should execute a target peak up maneuver every 4 orbits.
Coarse Track is now believed to cause degradation in mechanical bearings in the FGSs, and accordingly is no longer available as a guiding mode.
Guide-star acquisition times are typically 9 minutes. Reacquisitions following interruptions due to Earth occultations take about 6 minutes. It is also possible to take observations (primarily WFPC2 "snapshot" exposures) without guide stars, using only gyro pointing control. The absolute pointing accuracy using gyros is about 14" (one sigma), and the pointing drifts at a rate of 1.4 +/- 0.7 mas s**-1.
HST's "observing efficiency" may be defined as the fraction of the total time that is devoted to acquiring guide stars, acquiring astronomical targets, and exposing on them. In other words, the observing efficiency is defined as the ratio of "spacecraft time" to total time.
The main factors that limit the observing efficiency are (1) the low spacecraft orbit, with attendant frequent Earth occultation of most targets; (2) interruptions by passages through the South Atlantic Anomaly; (3) the relatively slow slew rate; (4) telemetry constraints; and (5) the performance of the scheduling algorithm.
During Cycle 7, it is anticipated that the observing efficiency will be about 50%. About 80% of the spacecraft time is allocated to scientific observations, with the remainder devoted to calibration and engineering observations (10%), and DD programs and repeats of failed observations (also 10%). Because of the allocation of about 6.8% of the scientific observing time to GTOs (see §3.5), the time available to GOs during Cycle 7 will be about 325 orbits per month, or approximately 3900 orbits during the entire 12-month cycle.
The procedure for estimating (and minimizing) the number of spacecraft orbits required for a given set of exposures is provided in §18. In addition to the on-target exposure time, the procedure takes into account target visibility durations, time required for guide-star acquisitions and reacquisitions and for target acquisitions, and instrument overheads and readout times.
All of the SIs are permanently mounted at the HST focal plane, so that all except the WFPC2 receive light that is slightly off-axis. A schematic diagram of the telescope focal plane is given in Fig. 2 (§13.6).
Tables 3(a)-(e) provide a summary of the capabilities of the SIs. For some applications, more than one instrument can accomplish a given task, but not necessarily with equal quality or speed.
The following subsections contain brief descriptions of the five SIs. After examining Tables 3(a)-(e), prospective proposers should read these descriptions in order to determine which SIs are likely to be most suitable for their programs. Revised and updated Instrument Handbooks, which discuss the SIs in detail, have been distributed to institutional libraries, and are available from STScI as described in §2. The Instrument Handbooks must be consulted before actual preparation of observing proposals. In addition, exposure simulators for the SIs are available to assist in the estimation of exposure times, as described in the Synphot User's Guide; users may contact the STScI Help Desk for more information.
Data from the following four SIs, which were removed from HST during the December 1993 servicing mission (WF/PC, HSP), or are planned for removal in Feburary 1997, are now available only in archival form:
Overviews of the capabilities of these four instruments are provided in Appendix D, which should be consulted by persons interested in proposing Archival Research funding with WF/PC, HSP, FOS, and/or GHRS data. Archival data from the WFPC2, FOC and FGS are, of course, also available from past Cycles.
Table 3: HST Instrument Capabilities
Table 3: HST Instrument Capabilities (continued)
Notes to Tables 3(a)-(e):
[1] WFPC2, FOC, and NICMOS have polarimetric imaging capabilities. The FOC, NICMOS, and STIS have coronographic capabilities.
[2] Predicted limiting V magnitude for an unreddened A0 V star in order to achieve a S/N ratio of 5 in an exposure time of 1 hour. Single entries refer to wavelengths near the center of the indicated wavelength range. For FOC direct imaging, the F342W filter was assumed. STIS direct imaging entries assume use of a clear filter. For this example V = H (relevant for NICMOS), since color terms are zero for an A0 V star. For STIS spectroscopy to achieve the specified S/N per wavelength pixel with a 0.5" slit, multiple values are given corresponding to 1300, 2800, and 6000Å respectively (if in range). For the NICMOS grism spectroscopy the three entries refer to 1.0, 1.4 and 2.0 microns with Grisms A, B, and C respectively.
[3] The WFPC2 has four CCD chips that are exposed simultaneously. Three are "wide-field" chips, each covering a 77" x 77" field and arranged in an "L" shape, and the fourth is a "planetary" chip covering a 35" x 35" field.
[4] The maximum FOV is 14" x 14", at full resolution it is 7" x 7". The available FOC configuration is referred to by its original f-ratio, f/96. With COSTAR the effective focal ratio is f/151. The f/288 configuration is no longer supported. Use of the f/48 is limited to LONG SLIT spectroscopy only.
[5] The three NICMOS cameras will usually be operated simultaneously and are offset from one another on 33" (1 to 2) and 48" (1 to 3) centers providing nearby, but not contiguous fields of view.
[6] The 25" slit is for the MAMA detectors, the 51" slit is for the CCD. The R ~150 entry for the prism on the near-UV MAMA is given for 2300Å.
[7] Slitless spectroscopy can be done using the FOC's "objective" prisms or NICMOS's "objective" grisms. All STIS modes can be operated in a slitless manner by replacing the slit by a clear aperture. WFPC2 has a capability of obtaining low-resolution "spectra" by placing a target successively at various locations in the WFPC2 ramp filter.
[8] For S/N = 1 in Fine Lock with default settings.
[9] Magnitude limit for primary star.
The WFPC2, which is HST's only on-axis instrument, is designed to provide digital imaging over a wide field of view (FOV). It has three "wide-field" charge-coupled devices (CCDs), and one high-resolution (or "planetary") CCD. Each CCD covers 800 x 800 pixels and is sensitive from 1200 to 11,000 Å. All four CCDs are exposed simultaneously, with the target of interest being placed as desired within the FOV.
The three Wide Field Camera (WFC) CCDs are arranged in an "L"-shaped FOV whose long side projects to 2.5', with a projected pixel size of 0.10". The Planetary Camera (PC) CCD has a FOV of 35" x 35", and a projected pixel size of 0.0455". A variety of filters may be inserted into the optical path. Polarimetry may be performed by placing a polarizer into the beam. A ramp filter exists that effectively allows one to image a small 3 10"object in an arbitrary 1-3% bandpass at any wavelength between 3700 and 9800 Å, by appropriately positioning the target within the FOV.
The WFC configuration provides the largest FOV available on HST, but undersamples the cores of stellar images; the PC configuration samples the images better, over its smaller FOV.
The FOC is intended to provide high-resolution images of small fields. The camera reimages the HST focal plane to provide two different scales. The focal ratios were originally f/96 and f/48; to avoid confusion these names are retained, but installation of COSTAR changed the effective focal ratios to f/151 and f/75, respectively. A variety of filters, prisms (for slitless spectroscopy), and polarizers may be placed in the optical beam.
The f/96 camera (plus COSTAR) has a FOV of 7" x 7" and a pixel size of 0.014" x 0.014" in its standard 512 x 512 format; a field of 14" x 14" can be used with the 512 x 1024 pixel format with a (rectangular) pixel size of 0.028" x 0.014". This camera provides two occulting fingers (0.3" and 0.5" wide) at the entrance aperture. The f/96 camera also has three polarization analyzers for polarimetric imaging.
Usage of the f/48 camera is currently restricted to LONG SLIT spectroscopy only; see the FOC Instrument Handbook for further details.
The FOC detector is a three-stage image intensifier, optically coupled to a television tube. Software centroids the individual photons. A variety of options is available for the size and shape of the area that is scanned and the spatial resolution. The dynamic range and limiting magnitude of the FOC depend on the readout format and the desired signal-to-noise ratio, but the limiting magnitude in a broad bandpass is about mU = 27.
In comparing the FOC and WFPC2, proposers should note the following: (1) the FOC provides the higher angular resolution at all wavelengths, and the WFPC2 provides the larger field of view; (2) the FOC is faster below about 4500 (Å), while the WFPC2 is faster above 4500 (Å).
The NICMOS provides HST's only infrared capability. The three 256 x 256 pixel cameras of NICMOS are designed to provide diffraction limited sampling to 1.0 micron (Camera 1), 1.75 micron (Camera 2), and offer via Camera 3 a relatively large field of view. The short wavelength response at 0.8 micron is set by the HgCdTe detector array, while a 2.6 micron cutoff was selected as the longest usable wavelength given HST's warm optics. The dewar lifetime of NICMOS is expected to be 4.5 years.
Each camera carries 19 independent optical elements providing a wide range of filter options. Cameras 1 and 2 have polarimetric filters, Camera 2 has a 0.3 arcsec radius coronographic spot and optimized cold mask, Camera 3 has three separate grisms providing slitless spectroscopy over the full NICMOS wavelength range. A variety of standard dithering and chopping (for background and sky mapping) sequences are available.
The three cameras are designed to be operated independently and simultaneously. Accordingly, proposers are strongly encouraged to request use of all three cameras in their Phase I submission. In cases where the user has no interest in obtaining multi-camera observations then the user will be expected to specify survey observations through standard filters at the Phase II submission. Details of our proposed survey programs are in the NICMOS Instrument Handbook.
STIS uses two-dimensional detectors operating from the ultraviolet to the near-infrared (1150-11,000Å) in support of a broad range of spectroscopic capabilities. STIS can be used to obtain spatially resolved, long slit (or slitless) spectroscopy from the full 1150-11,000Å range at low to medium spectral resolutions of R ~ 400 to 14,000 with first order gratings. Echelle spectroscopy at medium and high (R ~ 24,000 and 100,000) resolutions covering broad spectral ranges of Dl ~ 800 or 250Å respectively is available in the ultraviolet (1150-3100Å). STIS can also be used for imaging, although the filter complement is limited.
The three 1024 x 1024 pixel detectors supporting spectroscopy, target acquisitions, and limited imaging applications are:
The MAMA detectors support time resolutions down to 125 micro-sec in TIME-TAG mode, and the CCD can be cycled in <10 sec with use of narrow subarrays. The CCD also provides visible light coronographic imaging.
In normal operation, two of the FGSs are used for spacecraft attitude control. The third FGS thus has the potential of carrying out astrometric and photometric observations, including (1) measuring the relative positions of sources to a precision of a few milliarcseconds; (2) measuring the separations and magnitude differences of binary stars; and (3) measuring stellar angular diameters. Note that the FGSs were unaffected by the installation of COSTAR.
For positional measurements, the useful magnitude range is mv = 4 to 17 mag, and the precision is about +2 mas. Generally, a target star and 5 to 10 reference stars within the FOV annulus would be observed at several epochs to yield relative proper motions and parallaxes. Note that the effective FOV for parallax observations is reduced to about 4" x 5", since for observations six months apart the telescope's roll angle will differ by 180 degrees (see §11.2).
The "TRANS" mode for double-star and angular-diameter measurements is available, and considerable data-reduction and analysis software has been developed at STScI. This mode is nominally capable of measuring (1) separations down to 5 mas and magnitude differences of up to 4 mag, for double stars whose primaries are as faint as about mv = 14 mag, and (2) angular diameters above 20 mas. Similar measurements on non-stellar objects are also possible.
A new FGS is scheduled to be installed during SM97. Its utility as an astrometric device will be evaluated during the post-servicing mission observatory verification period. However, proposals should be based on FGS-3, currently being used for astrometry, which will remain on board the spacecraft.
Fig. 2 shows the layout of the instrument entrance apertures in the telescope focal plane, as projected onto the sky. The Instrument Handbooks should be consulted for details of each instrument's aperture sizes and orientations. The figure shows the physical locations of the WFPC2, NICMOS, STIS, and FGS apertures in the focal plane. The effective locations of the apertures for FOC are those of the first mirrors ("M1") in each of the two-mirror light paths provided by COSTAR. These effective locations are shown as open circles in Fig. 2.
In order to avoid confusion with the spacecraft's V2 and V3 axes, we define two new axes in Fig. 2, U2 and U3, which are fixed in the focal plane as projected onto the sky. At nominal roll (see §11.2), the U3 axis points toward the anti-Sun.
Table 4 lists the relative effective locations of the SI apertures; the U2,U3 coordinate system of Fig. 2 is used, and the linear dimensions have been converted to seconds of arc using a plate scale of 3.58 arcsec mm**-1. The locations of the WFPC2, FOC and FGS apertures are accurate to about +/-1", the predicted locations of the STIS and NICMOS apertures could be in error by as much as 10".
Table 4: Nominal Effective Relative Aperture Locations
Figure 2: Effective aperture locations for the instruments available after SM97 (see also Table 4).
Several of the SIs must be protected against over-illumination; these constraints are discussed below. Observations that violate these constraints should not be proposed. Note that there may be non-linearity, saturation, or residual-image effects that set in at substantially fainter limits than the safety limits discussed below; the Instrument Handbooks should be consulted for details.
1. WFPC2. No safety-related brightness limits.
2. FOC. May be damaged by continuous illumination by a star ofV 3 9 through a CLEAR filter anywhere in the field of view, or by an extended source with V surface brightness of < 12 mag arcsec**-2.
3. STIS. No safety-related brightness limits for the CCD. The STIS MAMA detectors can be damaged by excessive levels of illumination and are therefore protected by hardware safety mechanisms. In order to avoid triggering these safety mechanisms, absolute limits on the brightest targets which can be observed by STIS will be enforced by proposal screening. It is the GO's responsibility to provide accurate information to facilitate this process. It is STScI policy that observations lost due to MAMA bright object violations not be repeated.
In order to avoid exceeding the MAMA bright object limits, observations must never:
1) exceed a total count rate on either MAMA detector of 300,000 counts/sec.
2) exceed a maximum local count rate of 50 counts/sec/pixel (NUV-MAMA only).
3) exceed a maximum local count rate of 25 counts/sec/pixel (FUV-MAMA only).
4. NICMOS. No safety-related brightness limits.
5. FGS. Objects as bright as V = 1.8 may be observed if the 5-mag neutral-density filter is used. Observations on all objects brighter than V = 6.8 should be performed with this filter. There is a hardware limitation which prevents the Spiral Search phase of an FGS target acquisition from succeeding for any target brighter than V = 8 (3 with F5ND).
Table 5: HST Nominal Orbital Parameters (Epoch 1996.3)
As seen from HST, targets in most of the sky are occulted by the Earth for varying lengths of time during each 96-min orbit. Targets lying in the orbital plane are occulted for the longest interval, about 36 min per orbit. However, this is a purely geometric limit and does not include the additional time lost due to Earth-limb avoidance limits (see §11.2), guide-star acquisition or reacquisition, instrument setup, and SAA avoidance (§14.2). These orbital occultations are analogous to the diurnal cycle for ground-based observing and impose the most serious constraint limiting the efficiency of most HST observations.
The length of target occultation decreases with angle from the spacecraft orbital plane. Targets lying within 24 degrees of the orbital poles are not geometrically occulted at all during the HST orbit. However, the size of the resulting "Continuous Viewing Zones" (CVZs) is substantially reduced by the Earth-limb avoidance angles. Note also that scattered Earth light may be significant when HST observes near the bright Earth limb.
Since the orbital poles lie 285.5 from the celestial poles, any target located in the two declination zones near +/- 615.5 will be in the CVZ at some time during the 56-day HST precessional cycle. The maximum uninterrupted length of an observation may then be up to 7 days, although passages through the SAA (see below) will force gaps in coverage after a maximum of 8 orbits.
A detailed examination of all the observing constraints has shown that there are two distinct CVZ regions. The "heart" of the CVZ are those positions where substantial scheduling opportunities exist, and these observations will be treated as any other observation. The "wings" of the CVZ are those positions where limited scheduling opportunities exist, and so it is possible for those observations to come into conflict with other observations or contingencies. If a proposer elects to request CVZ time in the "wings", and the observations are not obtained in the limited CVZ opportunities, then those observations may NOT BE EXECUTED.
Above South America and the South Atlantic Ocean lies a lower extension of the Van Allen radiation belts called the South Atlantic Anomaly (SAA). No astronomical or calibration observations are possible during passages of the spacecraft through the SAA because of the high background induced in the detectors. SAA passages limit the longest possible uninterrupted exposures, even in the CVZs, to about 12 hours (or 8 orbits).
Because HST's orbit is low, atmospheric drag is significant. Moreover, the amount of drag varies, depending on the orientation of the telescope and the density of the atmosphere, which depends on the level of solar activity. The chief manifestation of this effect is that it is difficult to predict in advance where HST will be in its orbit at a given time. The position error may be as large as 30 km within two days of a determination of the position of the spacecraft in its orbit. A predicted position 44 days in the future may be up to ~4000 km (95% confidence level) in error.
This positional uncertainty affects observers of time-critical phenomena, since the target could be behind the Earth at the time of the event. In the worst case, it will not be known if a given event will be observable until a few days before the event.
Selection of guide stars (GSs) is carried out by the Guide Star Selection System (GSSS) at STScI. The required whole-sky coverage made it necessary for STScI to assemble a collection of survey plates as the basis for construction of a catalog of GS candidates. For the northern hemisphere (for which proper motions have now outdated the Palomar Sky Atlas), a special "Quick-V" survey was conducted for STScI with the 1.2-m Schmidt telescope at Palomar Observatory. The equatorial region and the southern hemisphere are covered by the SERC-J survey and its equatorial extension.
The Guide Star Catalog (GSC), which resulted from the digitization and analysis of the plate collection, contains information, including coordinates and magnitudes, on about 18 million objects to 14.5 mag.
The observation summary that is part of each Phase I observing proposal must include celestial coordinates for all fixed targets, but these coordinates need only be of sufficient accuracy for the scientific and technical reviews described in §7 (i.e., about +/- 1'). (For solar-system targets, see §15.3)
More accurate target coordinates are required in Phase II. Stellar proper motions (and parallaxes) will also be requested during Phase II, since even relatively small stellar motions can be surprisingly significant. Phase II proposers should be prepared to supply such information themselves.
Target acquisition is the method used to assure that the target is in the field of view of the requested aperture to the level of accuracy required by the science. There are several distinct methods of target acqusition; each has a different approach and different accuracy, and will take different amounts of time and resources to complete. The level of accuracy required depends most strongly on the size of the aperture to be used to take the science data and the nature of the scientific program.
15.2.1 Target Acquisition without the Ground System
No acquisition means that pointing control will be entirely on gyros, and FGSs will not be used. The telescope is slewed on gyro control from the last target. The pointing accuracy depends on the size of the slew from the previous target. The best-case uncertainty is 0.010" for each 30" displacement in the slew to the target.
Blind acquisition means that guide stars are acquired and the FGSs are used for pointing control. The pointing is accurate to the guide star position uncertainty, which is about 1".
Onboard acquisition means that software onboard the spacecraft specific to the science instrument in use will be used to center the fiducial point onto the target. On-board target acquisitions will be needed for all STIS spectroscopic observations, and for NICMOS coronographic observations. The WFPC2 and FOC do not have onboard acquisition capabilities. For specific information on methods and expected pointing accuracies, see the Instrument Handbook for the instrument to be used.
Early acquisition means using an image taken on an earlier visit to provide improved target coordinates for use with subsequent visits. Usually the WFPC is used to make the acquisition image several months in advance of the science observations. The observer will analyze the early acquisition image and provide the improved coordinates to the scheduling system.
15.2.2 Target Acquisition with the Ground System (OPUS)
Target acquisitions that cannot be accomplished reliably or efficiently via one of the above methods may still be possible by transmitting relevant data to the STScI, analyzing it to determine the needed pointing corrections, and then providing those corrections to the telescope. This description covers two kinds of activities, the "interactive acquisition" and the "reuse target offset", both of which are described briefly here. The observer who uses these capabilities will be supported by staff of the OPUS (the Observation Support/Post-Observation Data Processing (OSS/PODPS) Unified System) of the Data Systems Division.
Interactive acquisition, or real-time target acquisition, uses the ground system software to calculate the small angle maneuver to move the aperture onto the target. This method is available for all science instruments except the astrometry FGS. High data rate TDRSS links are required at the time the data is read out of the instrument to transmit the data to the ground, and at a subsequent time to re-point the telescope before the science observations, which adds a difficult constraint to the scheduling. The GO, or a designated representative, must be present at the STScI at the time of the acquisition. The acquisition data, usually an image, is analyzed by OPUS personnel to compute the image coordinates and centering slew for the target identified by the GO.
Reuse target offset means using an offset slew derived from an onboard acquisition done on visit 1 to reduce the amount of onboard acquisition time required for subsequent visits to the same target. The data from the initial visit are analyzed by OPUS personnel to provide the offset slew to be repeated for subsequent visits. All subsequent visits to the target must use the same guide stars as the initial visit, which limits the time span of all visits to a few weeks. There are additional instrument-specific requirements. The GO is advised to contact the STScI Help Desk if this capability is required.
Objects within the solar system have apparent motions with respect to the fixed stars. HST has the capability to point at and track moving targets, including planets, their satellites, and surface features on them, with sub-arcsecond accuracy. However, there are a variety of practical limitations on the use of these capabilities that must be considered before addressing the feasibility of any particular investigation.
Two specific aspects of solar-system observations are discussed below: the initial acquisition of a moving target, and the subsequent tracking of the target during the scientific observations. Only an overview of the current moving-target capabilities is given here. Phase I proposers are encouraged to consult the STScI Help Desk for more detailed information.
15.3.1 Tracking Capabilities
HST is capable of tracking moving targets with the same precision as for fixed targets (see §12.2). This is accomplished by maintaining FGS Fine Lock on guide stars, and driving the FGS star sensors in the appropriate path, thus moving HST so as to track the target. Tracking under FGS control is technically possible for apparent target motions up to 5 arcsec s**-1. In practice, however, this technique becomes infeasible for targets moving more than a few tenths of an arcsec s**-1. It is currently possible to begin observations under FGS control and then switch over to gyros when the guide stars have moved out of the FGS field of view. If sufficient guide stars are available, it is possible to "hand off" from one pair to another, but this will typically incur an additional pointing error of about 0.3".
Targets moving too fast for FGS control, but slower than 7.8 arcsec s**-1, can be observed under gyro control, with a loss in precision that depends on the length of the observation.
The track for a moving target is derived from its orbital elements. Orbital elements for all of the planets and most of their satellites are available at STScI. Moreover, STScI has access to the ASTCOM database, maintained by the Jet Propulsion Laboratory (JPL), which includes orbital elements for all of the numbered asteroids and many periodic comets. For other objects, the GO must provide orbital elements for the target in Phase II.
Offsets (using the same guide stars and performed under the same guide star acquisition) can be performed to an accuracy of about +/-0.02". The sizes of offsets are limited by the requirement that both guide stars remain within the respective FOVs of their FGSs. Offsets that continue across separate visits (including visits executed with the same guide stars), will typically encounter accuracy of ~0.3".
It is also possible to obtain data while HST scans across a small region of the sky. In all cases the region scanned must be a parallelogram (or a single scan line). Two types of "spatial scans" (i.e., raster scans) may be requested:
The possible scan area is limited by the requirement that the same guide stars be used throughout the scan, and the maximum possible scan rate for continuous scans is 1 arcsec s**-1. Continuous spatial scan lines cannot be interrupted and must therefore be completed within one orbital target-visibility period. Spatial scans requiring more than 45 minutes of spacecraft time should be avoided.
There are three options for preparing and submitting proposals:
It is the responsibility of applicants to mail their proposals early enough to assure arrival at STScI by the appropriate deadline. We also urge applicants to submit their electronic versions well before the deadline, to avoid possible last-minute hardware or overloading problems.
Fully Electronic Proposal Submission
For Cycle 7 STScI is encouraging a fully electronic submission. In this mode of submission, the proposer sends via electronic mail both the filled-in LaTeX proposal template AND the PostScript file output from LaTeX (which can incorporate any desired monochrome figures as encapsulated PostScript). For large PostScript files, an ftp area is available. For PostScript submissions, a separate acknowledgment will be sent upon successful printing of the file. This fully electronic submission would be in lieu of any paper submission. This mode does not apply to Archival Research proposals, for which signed budget forms are required.
Small (< 30 orbits) observing, and Snapshot proposals should be no longer than 10 pages, medium (30-99 orbits) observing proposals should not exceed 12 pages, and Major Program proposals (. 100 orbits) should not exceed 17 pages. Panel reviewers may ignore any pages beyond these limits.
Paper-plus-Electronic Submission
Under this option, observing and Archival research proposals are submitted in both electronic and paper form. Two (2) complete, single-sided copies of the paper proposal should be submitted to STScI. Proposers who wish to include glossies or color illustrations must make and send 20 double-sided copies of the proposal. Archival Research proposals should not exceed 10 pages.
U.S. proposers who are requesting funding for Archival Research should also include the following:
Note that the Budget Forms are not required in Phase I for observing proposals. Budget Forms will be requested in Phase II from successful U.S. observers only.
Student Principal Investigators (PIs) should enclose one copy of the
The following options exist for preparing the paper forms. All of them are acceptable, but the format and contents of the forms should not be changed in any way.
1. Request the proposal templates and the style file by return e-mail (see §17.2). Fill out the templates using standard text-editing software, run LaTeX, and then print out the proposal forms for submission. This option will be the most advantageous for the majority of proposers, since the identical template files can also be sent electronically to STScI to satisfy the electronic-submission requirement.
2. Use word-processing equipment or a typewriter to prepare facsimiles of the Phase I proposal. Note that the format of the submitted proposal should not deviate from that produced by the LaTeX form.
Paper-only Submission
If access to electronic mail is not available to a proposer, then it is permissible to submit the Phase I information to STScI solely on the paper forms. Explanation for this mode of submission should be provided in a cover letter. Note that the submission deadline for paper-only proposals is one week earlier than for paper-plus-electronic submissions, in order to reflect the significant additional STScI processing effort.
Where to Submit Proposals
Paper forms should be sent to the following address:
Science Program Selection Office
Space Telescope Science Institute
3700 San Martin Dr.
Baltimore, MD 21218 USA
The electronic version of the Proposal Template file (and optional postcript file) should be sent via e-mail directly to one of the following proposal-submission electronic mail addresses:
INTERNET: newprop@stsci.edu
NSI/DECnet: STSCIC::NEWPROP
Proposers will receive an acknowledgement of their e-mail transmission immediately after it is received at the STScI; if no acknowledgement is received within a few days, proposers should contact the STScI Help Desk. For PostScript submissions, a separate acknowledgment will be sent after printing of the file. Again, if no second acknowledgement is received within a few days, PostScript submitters should contact the STScI Help Desk. The electronic-mail user-id for general correspondence is help@stsci.edu, and the telephone number is 800-544-8125 (toll-free within the U.S.) or 410-338-1082.
European PIs and Co-Is should send an additional electronic version of the proposal template file to the ESA Project Scientist (for accounting and statistical purposes). The ESA HST Project Scientist electronic mail address is:
INTERNET: esahstps@eso.org
NSI/DECnet: ESO::ESAHSTPS
Alternatively, a paper copy should be sent to:
ESA HST Project Scientist
Space Telescope European Co-ordinating Facility
European Southern Observatory
Karl-Schwarzschild-Strasse 2
D-85748 Garching
Germany
This subsection discusses general procedures for proposal preparation and submission. Specific instructions for filling out the electronic proposal template can be found in §17.
The computer software used in the review and feasibility analysis of proposed HST observations can interpret the proposal information only if it is in the correct format. It is therefore essential that the proposal template be filled out carefully, accurately, completely, and in accordance with the instructions.
Step-by-step Instructions
1. Obtain the Template and Style Files
To obtain electronic copies of the LaTeX template files and the style files, please send an e-mail message to newprop@stsci.edu or STSCIC::NEWPROP containing the words "request templates" in the subject line. Proposers will receive the following files by automatic "return e-mail":
2. Fill out the Template File
Fill out the Phase I Proposal Template file using any text editor on the proposer's local computer. Instructions can be found in the template itself, and in §17. Electronic submission of items 12-17 is optional.
3. Prepare a Paper Copy of the Proposal
For most proposers, the easiest way to produce a paper copy of the proposal is to run LaTeX and then print the formatted proposal. If you are not familiar with LaTeX, please check with your system manager for how to run it on your system, and how to use PostScript encapsulation for any figures. The STScI Help Desk may also be contacted for assistance with any questions or problems. Rather than completing the LaTeX template version, some proposers may prefer to use different word processing software to produce a paper copy of the proposal.
4. Send the Template File Electronically
This is the "Unformatted Submission". Send the completed Phase I proposal LaTeX template file to the STScI by e-mail to the account named newprop (see Step 1 above) before the deadline for electronic submission. Please do not e-mail the PostScript version of the proposal that was produced as output by the LaTeX formatter for this first phase of the submission.
5. Send the Complete Proposal to STScI
There are three options for the "Formatted Submission". You can either send a postscript file via e-mail (5a), a postscript file via ftp (5b), or paper copies of the proposal (5c). Please select ONE of these options. Note that Archival research proposers MUST send paper copies.
5a. PostScript Submission via E-Mail
Send one postscript file, with figures included, to the STScI by e-mail to the account named newprop before the deadline for electronic submission. All figures must be encapsulated into the postscript file (i.e., send only ONE postscript file), and we can only accomodate black and white figures. Please set the formattedsubmission keyword in the LaTeX template to EMAIL.
5b. Postscript Submission via ftp
If your postscript file contains large figures some e-mail facilities may lead to truncation or corruption of the file. If you think this may be a problem for your submission, your postscript file should be transferred to the STScI via ftp. We have assigned a high security area for this purpose, and although you can put your files there, only the appropriate STScI staff can retrieve them. If you wish to use this option, please refer to the instructions given on-line (http://www.stsci.edu/proposer.html) or contact the STScI Help Desk. Do NOT use our public ftp area for your submission. Please set the formattedsubmission keyword in the LaTeX template to FTP.
5c. Make 2 Paper Copies and Send Them to STScI
Send the paper forms to the STScI before the appropriate deadline for paper or paper-plus-electronic submissions, as appropriate. The STScI will make the requisite copies for the proposal review process. These copies will be standard black and white Xerox copies. Proposers who wish to include glossies or color material must send 20 double-sided paper copies to the STScI. Archival Research proposals must include Budget Forms GF-97-1 through GF-97-3 with each copy of the proposal, and student PIs must include one copy of the certification letter from their faculty advisor. Please set the formattedsubmission keyword in the LaTeX template to PAPER.
Proposers should observe the following general instructions and conventions when filling out the forms:
Specific instructions for filling out various items in the proposal are given in this section and in the LaTeX template.
SNAP-Snapshot Survey proposal
CATEGORIES
SOLAR SYSTEM
COOL STARS-This category refers to stars with effective temperatures less than about 10.000 K, which are single or have non-interacting companions, and which are at the Main Sequence or later in their evolution.
HOT STARS AND STELLAR CORPSES-This category refers to stars which spend a significant fraction of their observable lives at an effective temperature of about 10,000 K, such as neutron stars, white dwarfs, Wolf-Rayet stars, luminous blue variables, and blue stragglers.
BINARY STARS-This category is appropriate when the interaction between stars is their most important defining characteristic.
YOUNG STARS AND CIRCUMSTELLAR MATERIAL-This category refers to newly formed stars and the material surrounding them. Proposals in this category must be mainly concerned with collapsing material surrounding the star (e.g., proto-planetary disks, extra-solar planets) or the star itself (e.g., T Tauri stars, FU Orionis stars) rather than dynamical effects on surrounding material (e.g., HH Objects).
STELLAR EJECTA-This category includes material ejected from stars or former stars. For example, it includes nova shells, supernovae, supernova remnants, stellar jets, HH objects, winds, planetary and proto-planetary nebulae.
INTERSTELLAR MATTER-This category includes the general properties of the Galactic interstellar medium; for example, diffuse gas observed in emission or absorption, dust, atomic or molecular clouds, or ionized gas in HII regions.
STELLAR POPULATIONS-This category refers to resolved stellar populations. For example, it includes luminosity functions or color-magnitude diagrams of stellar systems in the Milky Way Galaxy-open clusters, globular clusters, halo, disk, or bulge-or in nearby galaxies.
GALAXIES-This category includes galaxies in the Hubble sequence, starburst galaxies, IR-bright galaxies, dwarf galaxies, and low-surface-brightness galaxies, as well as extragalactic interstellar media and unresolved stellar populations within such galaxies. It does not include studies of gas in external galaxies through QSO absorption lines.
CLUSTERS OF GALAXIES-This category includes groups and clusters at all redshifts, and encompasses dynamical studies, cooling flows, evolution, and gravitational lensing by clusters.
AGN/QUASARS-This category includes active galactic nuclei, excluding starburst phenomena where the activity in the nucleus is insignificant.
QUASAR ABSORPTION LINES-This category addresses the physical properties and evolution of absorption line systems detected along the line of sight to quasars.
COSMOLOGY-This category addresses the universe as a whole, including measurement of cosmological parameters, peculiar velocity studies, surveys for distant objects, evolution of galaxies, and evolution of the universe.
KEYWORDS
-For Long-Term Programs (see §3.1.3), include only visits requested for Cycle 7.
-All visits and exposures for a given target that use the same instrument and mode may be summarized using a single OS line.
-Special calibration exposures on internal sources and calibration exposures using the Earth should not be indicated here, but should be listed only in Item #13- Description of the Observations-of the proposal form. They also should not be counted toward the total number of orbits given on the Cover Page; these additional orbits will be estimated by STScI staff and then communicated to the TAC reviewers. External astronomical calibration targets should be entered as separate lines on the OS, with the appropriate number of orbits.
-For SNAP proposals, the OS should be filled out with a typical example of a snapshot exposure (less than one orbit), including spectral element, etc.
-For each row of the observation summary, the following information must be provided:
1. TARGET NAME
Targets should be named using the conventions recommended in Appendix F.
2. TARGET RA AND DEC (J2000)
Supply the coordinates for fixed targets only. For generic targets use a very short text description either of the target location (e.g., HIGH-GALACTIC LATITUDE FIELD) or of the target itself.
It is important to note that the HST Scientific Instruments typically have very small apertures and fields of view. Target-acquisition apertures in some cases are only a few seconds of arc in size. It will be the successful proposer's responsibility in Phase II to provide coordinates accurate to about +1, for all approved targets which require onboard acquisition. Proposers can use the STScI Guide Star Selection System Astrometric Support Package (GASP) to obtain this accuracy in Phase II. For Phase I, however, target positions with accuracies better than +1¢ are sufficient for the TAC review (except in crowded fields where the identity of the target may be in question).
3. TARGET MAGNITUDE
Supply the apparent total magnitude in the V passband for the entire target (galaxy, planet, etc.), if known. This information is used only for scientific review, not for exposure-time calculations.
Note that some of the Scientific Instruments have limits on the brightness of the objects that they can observe safely. For more information, refer to §13.7 and the Instruments Handbooks.
4. Scientific Instrument Configuration and Operating Mode
Enter the Scientific Instrument configuration first, and then the operating mode. All of the allowable options can be found in the Instrument Handbooks.
5. SPECTRAL ELEMENT(S) (AND 
RANGE IF STIS)
All of the desired spectral element(s) (i.e., filters or gratings) should be entered (see the Instrument Handbooks for the allowable options). Several different spectral elements for different exposures may be included on the same OS exposure line, each separated with a comma and a space (e.g., F120M, F220W, F320W). If more than one element is required for the same exposure, then join the elements with a "+" (e.g., F277M+POL45). If the STIS is used, then list in parentheses (immediately following the spectral element listing) the total wavelength range in angstroms for the exposures defined on the given line; for example: (1100-1400).
6. TOTAL NUMBER OF ORBITS
Specify the total number of orbits (i.e., the sum of the orbits for all of the exposures from all target visits requested) (see §18).
7. SPECIAL REQUIREMENT FLAGS
Enter the flags listed in the Table below, where applicable. These five options are the only allowable entries.
Program Size Total Number of Orbits Maximum Length
Small < 30 orbits 3 pages
Medium 30-99 orbits 5 pages
Major . 100 orbits 10 pages
SNAP 3 pages
Up to two additional (optional) pages for figures, references, or tables are allowed. For long-term proposals, the total number of orbits refers to all cycles combined.
For the individual items below (#13-17) there are no specific page limits; however, the total proposal page limits (given at the beginning of this section) must be observed.
A visit is an exposure or series of consecutive exposures, with overheads, on a given target, and may consist of the following parts:
1. guide-star acquisition (to point HST at the target)
2. target acquisition (to place the target in an instrument aperture)
3. science exposure(s) (to obtain the data)
4. instrument overheads (to set up the instrument and read out the data)
5. instrument calibrations/overheads (if more than standard calibration is required)
If the visit lasts more than one orbit, it will continue with the following for each subsequent orbit:
6. guide-star re-acquisition (to keep HST pointed and locked after earth occultation)
7. science exposure(s)
8. instrument overheads
9. instrument calibrations/overheads
Thus, a typical visit for a spectroscopic observation (for the cameras, a target acquisition is usually not required) may look schematically like the following:
Note that some portion of the overheads may occur before the science exposure, but for the purposes of this calculation the overheads are all assumed to follow.
A new visit is required whenever a new set of guide stars must be acquired. Thus, whenever the following occurs, a new visit must be defined:
1. A change in target position of greater than 2'. Note that solar-system objects that move more than 2' during the observations may not necessarily require a new visit.
2. Repeated, periodic, or other time-separated observations with an interval between exposures such that one or more empty visibility periods would otherwise be required (e.g., to obtain an image of an object every 30 days for 5 times, or to obtain a spectrum of an object at phases 0.0, 0.3, 0.6). No visit should contain empty visibility periods.
3. Required large (> 55) changes in spacecraft roll orientation. These generally force the usage of different guide star pairs, and are therefore treated as separate visits.
4. A change in instrument (e.g., FOC/96 to STIS), except that coordinated primary and parallel observations are contained within the same visit. The switching of instruments requires a change of guide stars.
The maximum duration for a single visit is generally limited by the number of consecutive South Atlantic Anomaly (SAA)-free orbits (8 orbits); for shorter visits the impact of the SAA can be eliminated or minimized by careful scheduling (to place the SAA in the portion of the orbit when the target is occulted). Visits longer than 8 orbits must be broken into separate smaller visits, each with their own guide star and target acquisitions. If you feel that this does not apply to your program, please contact the STScI Help Desk. For astrometric observations using the FGS, each individual set (consisting of target object and reference objects) may be obtained in one visit if there is no telescope motion made during the sequence.
Step 1. Define your Observations and Group them into Visits
The first step in determining the number of orbits is to define the observations (instrument, mode, disperser, number of exposures, and exposure time) you need to execute on each target to accomplish your scientific objectives. You will then need to group your observations into separate visits following the rules given above.
Step 2. Determine the Visibility Period
The second step is for you to determine the "visibility period" for each target, which is defined as the amount of unocculted time per orbit (i.e., the amount of time per orbit during which observations can be made). This is done by using Table 7 below, which gives the visibility period as a function of target declination; values are also provided for moving targets, and for observations requiring shadow, low-sky, or CVZ observing conditions.
LOW-SKY: If the noise in your measurement will be dominated by zodiacal light, then you may wish to use the LOW-SKY scheduling restriction, which will assure that the sky background is within 30% of the yearly minimum for your target. This is achieved by restricting an observation to times that minimize both Zodiacal Light and Earthshine scattered by the OTA. The Zodiacal Light is minimized with a seasonal restriction, and the Earthshine is minimized by reducing the orbital visibility of the target by approximately 15% (the exact reduction depends on declination as shown in Table 7). If the LOW-SKY restriction is not used, for example, the Zodiacal Light background for low-ecliptic latitude targets can be as much as four times greater than the minimum value. Earthshine at the standard limb avoidance angle (20 degrees) exceeds the Zodiacal minimum by a similar factor. Use the orbital visibility given in the last column of Table 7 when computing the required number of orbits. Do not enter a flag on the Observation Summary for this condition.
SHADOW TIME: This refers to observing when HST is in Earth shadow, which can be useful for reducing the geocoronal Lyman alpha background. If you require low continuum background, use the LOW-SKY Special Requirement described above. If you require shadow time for your observations, then you have 25 minutes in which to obtain your science exposures regardless of target declination. Note that you may perform guide-star acquisitions/re-acquisitions, as well as end-of-orbit overheads, outside the narrower shadow time window (see the WFPC2 example in Appendix K).
MT (Moving Targets): These objects are generally in or near the ecliptic plane, so the visibility period will be ~ 53 minutes. Do not enter a flag on the Observation Summary for this condition.
CVZ (Continuous Viewing Zone): The CVZ includes the parts of the sky where the telescope can point continuously for the entire orbit(s) without being occulted by the Earth (see §§6.4, 14.1). If you can utilize CVZ time for your observations, then the visibility period is 96 minutes per orbit for 8 orbits, beyond which time SAA interference will limit the visibility to 75 minutes per orbit for the next 8 orbits. It may be to the proposer's advantage to select CVZ targets if possible, since the long visibility period of 96 minutes per orbit will allow a factor of two competitive advantage in terms of required resource charge (orbits) to perform the same science observations relative to non-CVZ targets. However, in practice the utility of CVZ observations could be reduced because the special requirements SHADOW TIME and LOW SKY are inconsistent with CVZ observations. While the brightness of the scattered Earthshine background during CVZ observations is not greater than during non-CVZ observations (since the same bright limb avoidance angle is used), the duration of high background can be considerably greater since the line of sight can graze the bright Earth limb during CVZ observations. It may also not be possible to schedule observations that require special timing as CVZ targets. Observation sets that will use (Phase II Special Requirements): ORIENT, ON HOLD (for targets of opportunity), AFTER, BETWEEN, or PHASE restrictions should therefore adopt the non-CVZ target visibility period for resource estimation. Also note that there are other limitations (e.g., data volume) that may affect CVZ availability.
Requests to remove the CVZ requirement in Phase II will be considered only in extraordinary circumstances. Similarly, requests to add the CVZ special requirement in Phase II will not generally be considered. See §6.4 for a detailed discussion of CVZ related policies.
Step 3. Map out the Orbits in each Visit
The third step is to fit science exposures and necessary overheads into the visibility period of each orbit, for all the visits required. The better you can pack your orbits, the more efficient your proposal will be. Examples of how this can be done for each instrument, and for several observing modes, are provided in Appendix K, as are standard worksheets for each science instrument. Do not submit the worksheets with your Phase I proposal.
Step 3.1 Guide Star Acquisitions
For all observations (except WFPC2 and NICMOS-Camera 3 SNAPs, see below), a guide-star acquisition is required, which takes 9 minutes. At the beginning of subsequent orbits in a multi-orbit visit, a shorter guide-star re-acquisition is required, which takes 6 minutes. For CVZ observations in which the visibility period is 96 minutes, guide-star re-acquisitions are not required; however, if your CVZ observation extends into SAA-impacted orbits, then guide-star re-acquisitions are required for those orbits. If you are obtaining very short exposures with the WFPC2 or NICMOS-Camera 3 (in a Snapshot proposal) and wish to utilize the gyro guiding mode (see §12.2 for pointing accuracy information), then use of guide stars is not required.
Step 3.2 Target Acquisitions
Following the guide-star acquisition, a target acquisition may be required, depending on the instrument used.
FGS, WFPC2, FOC: For the FGS, observations are done following a standard Spiral Search location sequence. Most WFPC2 and FOC observations also do not require a target acquisition. However, if you require precise positioning of the target (accuracy better than 1-2,) with the cameras, you will need an interactive acquisition (see §15.2.2 and the Instrument Handbooks). Note that there are no additional overheads for the FOC bright target acquisition procedure.
STIS: Following the initial guide star acquisition for your visit, the target location in the aperture plane will be known to an accuracy of -1-2 arcseconds. For science observations taken through spectroscopic slits which are less than 3 arcseconds in either dimension and for imaging observations taken using one of the coronagraphic apertures, you will need to use an on-board STIS target acquisition and possibly an acquisition peakup exposure to center your target. On-board target acquisitions with STIS differ considerably from previous HST instruments such as FOS and GHRS, which required raster scans to locate the target. STIS target acquisitions employ the CCD camera to image the target's field directly and onboard flight software processes the image to locate the position of the target. This should make STIS target acquisitions more robust than with the earlier generation HST spectrographs.
Acquisitions: STIS target acquisition exposures (MODE=ACQ) always use the CCD, one of the filtered or unfiltered apertures for CCD imaging and a mirror as the optical element in the grating wheel. Acquisition exposures center your target in the slit or behind a coronographic bar to an accuracy of 0.1 arseconds. A typical STIS target acquisition exposure takes 8 minutes.
Peakups: Additionally, an acquisition peakup exposure (MODE=ACQ/PEAKUP) must be taken following the target acquisition exposure to refine the target centering of point or point-like sources in slits less than or equal to 0.2 arcseconds wide (or tall). Peakup exposures use a science slit or coronagraphic aperture and can be taken with either the CCD or one of the MAMAs as the detector and with either a mirror or a spectroscopic element in the grating wheel. Typical centering accuracies following a peakup sequence are 0.3 and 0.2 times the dimension of the slit or bar for CCD and MAMA acq/peaks, respectively. Typical STIS imaging point source peakups take ~5-10 minutes, though a peakup with the very small 0.1 x 0.09 echelle aperture will take ~20 minutes. See Chapter 8 of the STIS Instrument Handbook for more details.
NICMOS: Most of the NICMOS observations do not require a target acquisition. However, some care should be taken in specifying coordinates for observations with the NICMOS Camera 1, which has a Field of View of only 11" x 11". For observations requiring positioning of the target to an accuracy of better than 1-2", the same requirements as for WFPC2 and FOC apply.
For coronography (NICMOS Camera 2), an on-board acquisition is performed to place the target under the coronographic spot. Once the target is in the Field of View of Camera 2, the on-board software determines the position of the brightest pixel, calculates the offset between that pixel and the coronographic spot, and moves the target under the spot. The overhead required for this process is 98 seconds.
Early Acquisitions: Early Acquisitions are simply science images obtained in visit 1, followed by science images/spectra obtained in visit 2 (scheduled at a later time).
Interactive Acquisition: If you require an interactive acquisition, treat the image obtained as a science exposure (see below), then add 30 minutes for the realtime contact (which may overlap the occultation interval at the end of an orbit). If you feel you need to utilize this capability, please consult the Instrument Handbooks and contact the STScI Help Desk.
Step 3.3 Science Exposures and Instrument Overheads
Following the target acquisition, you should place the science exposures in the orbit. The time allocation for these exposures consists of two parts-the exposure time and the instrument overhead. The exposure times were determined in Step 1, while the instrument overheads are given in Table 3 below (and on the worksheets) for each instrument operating mode.
WFPC2: Note that all WFPC2 images with exposure times longer than 10 minutes will be split (by default in the ratio 0.5+0.2) to allow for cosmic-ray subtraction (CR-SPLIT). These should be counted as separate exposures when mapping out your observations, although one overhead time is required (this time accounts for the fact that there are two exposures). If you have exposures shorter than 10 minutes, or do not wish to split your exposures, then use the NO CR-SPLIT overhead time. All exposures with the Linear Ramp Filters (LRF) require an additional 2 minutes of overhead due to repositioning of the telescope. Note that many short WFPC2 exposures in one orbit can overload the data paths. No more than 14 exposures per orbit are allowed.
When placing the science observations into the visit, it is important to note that WFPC2 exposures cannot be paused across orbits. This means that if you have 20 minutes left in an orbit, you can only insert an exposure that takes 20 minutes or less (including overhead). If you wish to obtain a 30 minute exposure, then you can either put it all into the next orbit, or you can specify, e.g., a 20 minute exposure in the first orbit, and a second exposure of 10 minutes in the next orbit (and thus include two exposure overheads).
A number of WFPC2 users have employed dithering, or small spatial displacements, to allow better removal of chip defects and the reconstruction of sub-pixel resolution. During Phase II the user will be given access to "canned" dithering routines, which will avoid many of the tricky details involved in planning spatial scans. The overhead for dithering, however, can be noticeable, about 1 minute for each move. The advantages, disadvantages, and overhead associated with dithering are discussed in more detail in the WFPC2 Instrument Handbook.
FOC: FOC exposures cannot be paused across orbits.
STIS: Some differences will be found between the overhead times presented here in Table 8 and those discussed in §9 of the STIS Instrument Handbook. While both times are based on the same preliminary data, the times presented here are a simplified, slightly more conservative version of those presented in the handbook. Our primary goal here is to ensure that you are requesting sufficient orbits for your observations. The STIS sample worksheets found in Appendix K, use the simplified method presented here in the Call for Proposals on the same examples described in §9 of the STIS Instrument Handbook.
When calculating STIS MAMA overhead times, we refer to spectroscopy and imaging. STIS MAMA spectroscopy are those observations obtained with either the NUV or FUV MAMA detector and a grating while STIS MAMA imaging are those observations with the NUV or FUV MAMA and a mirror in place.
The overhead times are presented as those required per exposure or the overhead times required for a subsequent exposure with no change from the previous exposure. This means that the two exposures are taken with the same aperture and grating in place and that the same wavelength is specified. The exposure times can be different between the two exposures. If you're in doubt about whether or not you would need to make a change, please assume a change for these Phase I estimates to avoid an orbit allocation shortfall later.
NICMOS: The instrument set-up at the beginning of an orbit, each filter change, change of Camera (e.g., from 1 to 3), and dithering/chopping, involve additional overheads (see Chapter 8 of the NICMOS Instrument Handbook). For instance, the instrument set-up at the beginning of an orbit needs 12 seconds, and filter changes need 12 seconds. The overheads for Camera changes depend on the starting and ending Camera: the overhead is 102 seconds from Camera 2 to 3 (and vice versa), 55 seconds from 1 to 2, and 70 seconds from 1 to 3. Many detailed examples are presented in the NICMOS Instrument Handbook (Chapter 8) to help the proposer through these numbers. NICMOS observations cannot be paused across orbits. The overhead on the ACCUM mode is a function of the number of reads, NREAD, obtained at the beginning (and at the end) of an exposure. The range of allowed NREADs is 1 (default) to 25. The two available readout modes, FAST and SLOW, are explained in detail in the NICMOS Instrument Handbook. The overhead on the BRIGHTOBJ mode is a function of the exposure time. The ACQuisition mode is available for Camera 2 only, and, specifically, for acquiring targets under the coronographic spot.
FGS: FGS observations cannot be paused across orbits.
Moving Targets: The onboard tracking command that is used for moving-target observations does not allow an observation (exposure plus overhead) to be longer than 33 minutes. The result is that long exposures must be split into two or more shorter exposures with separate instrument overheads for each piece.
Small Angle Maneuvers: These are changes in telescope pointing of less than 2¢. If you are offsetting by 1¢-2¢, add 1 minute of overhead.
Spatial Scans: Spatial scan timing is very dependent on the type and size of the scan. A general rule of thumb that can be used to estimate the orbit time overheads associated with spatial scans is to add
(Number_of_Steps-1) x Small_Angle_Maneuver_time
to the exposure time and overheads where SAM_time is defined as follows:
For example, if your exposure time + overhead/exposure is 4 minutes per exposure and you're planning a 4 point scan with 5" between points, you would allow 17.5 minutes for the total duration of the sequence:
total exposure time overhead = 16 minutes
total scan overhead = 1.5 minutes [(4-1) x 0.5]
More precise spatial scan timing information is only available by using the Phase II Remote Proposal Submission software (RPS2). Contact the STScI Help Desk if you are a new HST user and need instructions for accessing the RPS2 software.
Reuse Target Offset: For those programs with multiple visits to the same target within a three-week period (start to finish), you may be able to utilize the "reuse target offset" function. Please contact the STScI Help Desk if you feel your program can benefit from this capability. If reuse target offset is appropriate for your program, you should only include the target acquisition sequence in the initial visit; the subsequent visits should start with your science exposures.
Parallel Observations: These are treated just like primary observations. Although the primary program will be responsible for performing the guide-star acquisitions and target acquisitions, the time for these overheads must still be considered in mapping parallel exposures.
For coordinated parallel observations, where you know the visit structure of the prime observations, the mapping of parallels should be straightforward. For pure parallel observations, where you may not know the prime target declinations, you should use one of the following to determine the visibility period:
1. The minimum allowable visibility period based on the target selection criteria converted to a
declination range (e.g., if the generic requirement calls for 
, use 59 minutes)
or
2. if you cannot do the above, map out the exposures (plus overheads) you wish to obtain in an orbit for any legal visibility period (52-60 minutes). If you choose this method, you may need to decrease your exposure times when you are matched with the prime observation if it has a lesser visibility period than you selected; you will be contacted by your Contact Scientist if a reduction is required.
Step 4. Add up all the orbits
Once all the visits are defined, simply add the number of orbits in each visit, and insert the number of orbits for each target/instrument combination into the proposal template. Note that only whole orbits can be requested, and only whole orbits will be allocated. (The reason for this limitation is that the combined overhead for slew, guide star acquisition, and other overheads makes it very unlikely that an unused portion of a visibility period can be effectively used by another science program.)
Note that Snapshot proposals (see §3.2) will most likely take less than one orbit per observation. Proposers should make certain that each of their exposures (with overheads) requires £ 1visibility period. Although whole orbits will be allocated, the actual schedule construction may result in a few orbits per week not being completely filled. It is these holes that are candidate times for SNAPs.
Completed HST observations whose proprietary periods have expired are available to the community through the HST Archival Research Program. Funding may also be available for U.S. astronomers to support the analysis of such data. This section describes how to prepare and submit Archival Research proposals for cases where funding is requested. See §5.3 for a discussion of the HST Archival Research Program, and refer to Appendix H for instructions on how to access the HST Archive using StarView. Consult the HST Archive Primer for more detailed information about the HST Archive and for instructions on how to request archival data when funding is not requested. Additional Archive information and a registration form are available via the World-Wide Web at http://www.stsci.edu/archive.html.
Researchers proposing an Archival Research program that will also utilize data from other NASA centers should submit their AR proposals to the STScI if the majority of the program involves HST archival data and its analysis. Conversely, requests for support of Archival Research programs utilizing data primarily from other missions should follow the guidelines in the appropriate NASA Research Announcements.
Archival Research proposals (that request funding) should be submitted using the Cycle 7 Phase I Archival Research Proposal Template and budget forms. The scientific justification for AR proposals must be no more than 3 pages in length. Two additional pages for figures, references, and tables are also allowed. Specific instructions for filling out various items in the AR proposal form are given in this section and in the LaTeX template.
STScI may provide financial support to U.S. observers and Archival Researchers, subject to availability of funds from NASA. For information concerning the allowability of costs and funding procedures, see §5.3.
Archival Researchers must indicate the need for funding on the Proposal Cover Page. Budget Forms GF-97-1 through GF-97-3 are required only for Archival Research Proposals. The instructions for filling out the Budget Forms are included on the back of the forms in Appendix L. A copy of the forms should be attached to both copies of the proposal. The forms are available in LaTeX format as well as in Lotus and Excel formats on STEIS.
Specific questions concerning the allowability of costs or the preparation of the budget should be directed to the Grants Administration Branch (410-338-4200).
E-mail Phone
STScI Help Desk help@stsci.edu 1082
(toll free U.S. number: 1-800-544-8125)
Director's Office
Director Robert E. Williams wms@stsci.edu 4710
Deputy Director Michael G. Hauser hauser@stsci.edu 4730
Assoc. Director for Science Programs F. Duccio Macchetto macchetto@stsci.edu 4790
PRESTO Project
Lead, PRESTO Project Office Peg Stanley pstanley@stsci.edu 4536
Assoc. Lead, PRESTO Glenn Miller miller@stsci.edu 4738
Science Program Selection Office
Head Meg Urry cmu@stsci.edu 4593
Technical Manager Brett Blacker blacker@stsci.edu 1281
Science Support Division
Head Knox Long long@stsci.edu 4862
Grants Administration Branch
Chief Ray Beaser beaser@stsci.edu 4203
Data Systems Division
Archive Hotseat archive@stsci.edu 4547
Miscellaneous
Main switchboard/receptionist 4700
Fax 4767
Space Telescope European Coordinating Facility
The Space Telescope European Coordinating Facility (ST-ECF) provides HST information to European astronomers. Questions and requests may be directed to the ST-ECF as follows:
Mail: The postal address is:
Space Telescope-European Coordinating Facility
European Southern Observatory
Karl-Schwarzschild-Str. 2
D-85748 Garching bei München
Germany
Telephone: +49-89-320-06-291 / FAX: +49-89-320-06-480
Electronic Mail: ST-ECF has a special account for HST-related inquiries, whose address is stdesk@eso.org. There is also an anonymous ftp account from which HST-related programs and data can be downloaded:
ecf.hq.eso.org (or 134.171.11.4)
For details of electronic access, including access through the Web, see articles in recent issues of the ST-ECF Newsletter. The Newsletter, although aimed principally at European HST users, contains articles of general interest to the HST community. Those who wish to subscribe should contact the Newsletter Editor at the ST-ECF.
Canadian Astronomy Data Centre
Canadian proposers may obtain assistance from the Canadian Astronomy Data Centre (CADC). Questions and requests may be directed to the CADC as follows:
Mail: The postal address is:
CADC/DAO
5071 W. Saanich Rd.
Victoria, B.C. V8X 4M6
Canada
Telephone: 604-363-0025
Electronic Mail: cadc@dao.nrc.ca
B. STScI Electronic Information Service (STEIS)
STEIS is the electronic information system for HST users. This service provides access to a wide variety of HST-related information, including the latest updates on mission schedules and status, spacecraft and instrument performance, proposal deadlines, and data-analysis software (including updates and bug fixes).
There are two ways to access the information provided by STEIS to the Internet. The easier is via the World-Wide Web (WWW) using a graphical browser like Netscape, Mosaic, or Microsoft Internet Explorer, or a text-only browser like Lynx (from the University of Kansas). The URL (Universal Resource Locator) for the STEIS "home page" is:
http://www.stsci.edu/
From this page you can follow links to items of interest, including documentation updates and last-minute news.
Another way to access information on STEIS is via the anonymous file transfer protocol (FTP) mechanism. This method may be more suitable if you have a slow Internet connection. Connect to the STScI server machine (ftp.stsci.edu) to browse and retrieve files of interest. Items of particular interest to proposers can be found in the "proposers" subdirectory. Be sure to retrieve the file "how_to_submit". You may also contact the STScI Help Desk for assistance or for a copy of The STEIS Guide.
If you have any problems connecting to the STScI system, then please consult your local system administrator or network expert, or contact the STScI Help Desk. Please also forward comments or suggestions regarding this service to the STScI Help Desk. For more information on STEIS, please refer to The STEIS Guide.
Funding from STScI may be requested by scientists who are (1) United States citizens residing in the U.S., or abroad if salary and support are being paid by a U.S. institution; (2) U.S. permanent residents and foreign-national scientists working in and funded by U.S. institutions in the U.S.; or (3) U.S. Co-Investigators (Co-Is) on observing projects with non-U.S. Principal Investigators (PIs).
Proposals for funding will be accepted from Universities and other nonprofit research institutions, private for-profit organizations, Federal employees, STScI employees, and unaffiliated scientists. For-profit organizations should note that profit is not an allowable cost for GO/AR grants.
STScI encourages collaboration by scientists from different institutions in order to make the best use of HST observing time and STScI financial support. Where multiple organizations are involved, it is normally required that the proposal be submitted by only one institution, with one scientist designated as PI with full responsibility for the scientific and administrative organization of the project. The proposal should clearly describe the role of the other institutions and the proposed managerial arrangements. STScI will award funding to the designated PI institution and to the Co-I institutions. In special circumstances, a single grant may be awarded to the PI institution, which will provide Co-I funding through subgrants or subcontracts.
When a U.S. PI obtains grant funds from STScI for a project involving non-U.S. Co-Is, no funding may flow through the U.S. PI to the non-U.S. Co-Is.
U.S. Co-Is requesting funds for a proposal submitted by a non-U.S. PI are required to submit the Phase II budget forms through one of the Co-I institutions. Approved funding will be awarded by STScI directly to the Co-I institutions.
Support may be requested for the acquisition, calibration, analysis, and publication of HST data, and related costs.
The following costs are allowable:
1. Salaries and wages. Salary support for project investigators is allowable, provided it is consistent with the policies of the institution assuming responsibility for the grant.
STScI funds may not be used to pay more than a person's full-time salary or to pay more than an individual's hourly rate. Also, an individual may not be reimbursed for consulting or other work in addition to a regular full-time institutional salary covering the same period of employment. For faculty members in academic institutions, STScI funding will normally be limited to no more than two months of summer-salary support. Exceptions for released time during the academic year may be permitted in special circumstances, but such costs must be fully justified in the proposal.
Released time for project investigators working in non-academic institutions is allowable, provided the compensation requested is reasonable and consistent with each employee's regular full-time salary or rate of compensation.
It is assumed that most scientists will be affiliated with, and apply to STScI through, institutions that will make substantial support available for project activities (e.g., computer facilities, collaboration with other scientists, students, or research assistants). Salary support may be requested for unaffiliated scientists, but must be justified in the proposal, preferably in terms of the scientist's salary while most recently affiliated with an institution, or the salary that would be received if the scientist were currently employed on a full-time basis rather than working on the HST project.
2. Research assistance. Reasonable costs for graduate students, post-doctoral associates, data aides, and secretarial and technical support for the analysis of HST data are allowable. For post-doctoral associates and other professionals, each position should be listed with the number of months, percentage of time that will be spent on the project, and rate of pay (hourly, monthly, or annual). For graduate students and secretarial, clerical, and technical staff, only the total number of persons and the total amount of salaries per year in each category are required. All such salaries must be in accordance with the standard policies of the institution assuming responsibility for the project.
3. Fringe benefits. If an institution's usual accounting practices provide that its contributions to employee "benefits" (Social Security, retirement, etc.) be treated as direct costs, STScI funds may be requested for all applicable fringe benefits.
4. Publication costs. Reasonable costs for publication of research results obtained from the analysis of HST data are allowable.
5. Travel. Transportation and subsistence costs for project personnel to obtain, analyze, and disseminate direct results of HST observations are allowable, provided such costs have been justified in the proposal and fully detailed in the budget. Such costs must be in accordance with the written travel policies of the institution assuming responsibility for the project. In lieu of an institutional travel policy, the Federal Travel Regulations may be used for guidance.
6. Computer services. The costs of computer time and software for the analysis of HST data are allowable. Details of the services and software that will be used must be fully described and justified in the proposal.
7. Permanent equipment. The purchase of permanent equipment (items costing over $1000), including computers or related hardware, will be approved in special circumstances, and a detailed justification must be provided in the proposal. If such equipment is requested, the proposal must certify that the equipment is not otherwise available to project personnel, and/or that the cost of renting the equipment (or usage charges) would exceed the purchase price. It is expected that, in most instances, the recipient organization will provide at least half of the purchase price of any item costing over $10,000.
Unless stated to the contrary in the Grant Award Document, title to and all responsibility for equipment purchased with grant funds will be vested in the grantee institution, provided that the grantee uses the equipment for the authorized activities of the project and provided that the grantee agrees to transfer title to the equipment to the designee of STScI or NASA if a request for such transfer should be made within 120 days after the completion of the project. However, if the grantee organization has provided at least half of the purchase price of the equipment, STScI will vest title to such equipment in the grantee institution. Normally, the purchase of equipment will not be approved in grants to unaffiliated individuals or for-profit organizations. A detailed list of equipment purchased with grant funds must be provided with the required final financial report at the end of the grant period.
8. Materials and supplies. Materials and supplies directly related to the analysis of HST data are allowable, provided such costs are not already reimbursed through indirect costs.
9. Funds to support ground-based observations. Funding for preparatory observations is allowable for the acquisition of astrometric data to obtain accurate target positions for an observer's approved HST program. Ground-based observations that are clearly essential to the interpretation of HST observations are also allowable. A description and justification of the planned observations must be provided in the Budget Narrative Form submitted in Phase II. The total cost of the ground-based observations must be only a small portion of the overall budget to analyze HST data.
10. Indirect costs (IDCs). Indirect costs are allowable, provided that the IDC rate used in the budget is based on a Negotiation Agreement with the Federal Government. STScI will exclude from the indirect cost base all subcontracts and subgrants in excess of $10,000. Should funding be approved for the project, the grantee will be requested to submit one copy of the Federal IDC Negotiation Agreement to the STScI Grants Administration Branch.
For institutions without a negotiated rate, STScI may allow a charge of 10% of direct costs, less items that would distort this base, such as major equipment purchases. However, the charge must not exceed $5,000 and documentation must be available to support the amount charged. Alternatively, such institutions may show such expenses as direct costs to the project, provided documentation will be maintained to verify such costs. Unaffiliated scientists should not use an indirect cost rate; instead, all administrative costs should be shown as direct costs of the project. Please see the budget guidelines in Appendix L for additional information on allowable costs.
Questions concerning funding policies and the budget forms should be directed to the STScI Grants Administration Branch.
General Observers may request early funding of their programs if necessary to prepare for the receipt of HST data. Proposers may request up to 10% of the funds for their programs to be awarded prior to the start of the Cycle 7 observing schedule. Preparatory funding may be requested in item 12 on Budget Form GF-97-2 when the budget is submitted in Phase II. Note that the preparatory funds are part of the overall funding allocated for the program, not additional funds.
It is anticipated that STScI will award funding for periods of one to two years, depending on the nature and complexity of the project, to complete the analysis of the current cycle's observations. If the requested support is for more than one year, funding for the project will be on an annual basis, with additional funding for each subsequent grant year awarded after a favorable review of an annual performance report that will be required.
Long-term projects that are approved for more than one cycle of observations will be funded on an annual basis. Such programs require an annual continuation proposal, as described in §3.1.3. A budget for the analysis of current Cycle observations must be submitted with an estimate of the funding requirements for subsequent Cycles. Funding for subsequent Cycles will be provided through an amendment to an existing STScI grant.
Shortly before the start of Cycle 7, each PI will receive notification from the Director concerning the specific funding allocation for their GO program. It is anticipated that requests for preparatory funding will be awarded prior to the start of Cycle 7. Additional funding up to the approved funding allocation will be awarded after the receipt of observational data for each GO program.
Funded HST proposers are invited to apply to the Initiative to Develop Education through Astronomy (IDEA) program, which is sponsored and funded by NASA Headquarters. This program typically provides a modest supplement ($6,000) to existing NASA Astrophysics or STScI grants in order to enhance the participation of research astronomers in pre-collegiate or public outreach activities. All current Principal Investigators funded through the NASA Astrophysics Division or STScI are eligible to apply for an IDEA award. For more information, contact Carole Rest, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, or send e-mail to idea@stsci.edu.
The WF/PC had two configurations; in both, the FOV was covered by a mosaic of four charge-coupled devices (CCDs). Each CCD had 800 ¥ 800 pixels and was sensitive from 1150 to 11,000 Å. However, internal contaminants on the camera optics limited normal operation to the range from 2840 to 11,000 Å.
In the Wide Field Camera (low-resolution) configuration, the FOV was 2¢.6 ¥ 2¢.6, with a pixel size of 0,.10. In the Planetary Camera (high-resolution) configuration, the FOV was 1¢.1 ¥ 1¢.1, and the pixel size was 0,.043. A variety of filters was available. The WF/PC received about 40% of the observing time on HST in Cycles 1-3, with a large and diverse range of science observations resulting. All WF/PC data was adversely affected by the existence of spherical aberration. Unique and valuable data exists in the archive, but in terms of photometric accuracy, and especially image quality, data taken with the WFPC2 from Cycle 4 and on is superior.
The HSP was designed to take advantage of the lack of atmospheric scintillation for a telescope in orbit, as well as to provide good ultraviolet performance. Integrations as short as 10 ms were possible, over a broad wavelength range (1200 to 8000 Å), and polarimetry was also possible. Observations were carried out through aperture diameters of 1,.0 with the visual and ultraviolet detectors, and 0,.65 with the polarimetry detector.
HSP had a large variety of fixed aperture/filter combinations distributed in the focal plane; selection was accomplished by moving the telescope so as to place the target in the desired aperture behind the desired filter.
The HSP detectors were four image-dissector tubes and one photomultiplier tube. A variety of ultraviolet and visual filters and polarizers was available. The HSP was used for only a relatively small fraction (5%) of HST observing in Cycles 1-3; the HSP science program was among the more severely compromised by spherical aberration. Only limited instrument expertise is available at STScI in support of HSP Archival Research. The extremely high speed with which some HSP data was acquired make these still unique for either past, current or planned HST capabilities.
The FOS performed low and moderate resolution spectroscopy (R ~ 250 and 1300) in the wavelength range 1150 to 8500 Å. A variety of apertures of different sizes and shapes were available which could optimize throughput and spectral or spatial resolution. Ultraviolet linear and circular spectropolarimetric capability was also present.
Two gratings and a prism were available in the R = 250 mode and six gratings were available in the R = 1300 mode to cover the entire spectral range. The photon-counting detectors were two 512-element Digicons, one which operated from 1150 to 5500 Å (FOS/BLUE), and the other from 1620 to 8500 Å (FOS/RED).
The FOS acquired data in accumulation, rapid-readout, periodic, and image modes. Time resolutions as short as 30 msec were feasible. The electron image was magnetically stepped through a programmed pattern during the observations which provided for oversampling, compensation for sensitivity variations along the Digicon array, sky measures, and/or measurement of orthogonally polarized spectra. Normally data were read out in intervals that were short compared to the exposure time.
The FOS received about 20-25% of the total HST observing time over Cycles 1-6. with a large and diverse range of high quality science observations resulting. Due to the polarimetric and large dynamic range capabilities a substantial fraction of these data will remain unique.
The GHRS used two, 500-element digicon detectors providing sensitivity from 1100 to 1900 Å (Side 1-solar blind) and 1150 to 3200 Å (Side 2). The GHRS provided photon-noise limited data if an observing strategy was undertaken to map out photocathode response irregularities with the FP-SPLIT option. Signal-to-noise ratios of 100 or more were routinely achieved, and upwards of 1000 on occasion.
The GHRS modes include a first order grating covering 1100-1900 Å at R ~ 2,500 (285 Å bandpass), four first order holographic gratings with very low scattered light covering 1150-3200 Å at R ~ 25,000 (27-45 Å bandpass), and cross-dispersed echelles at R ~80,000 over 1150-3200 Å (6-15 Å bandpass).
The GHRS had two apertures: the 2.0" Large Science Aperture, and 0.25" Small Science Aperture; post-COSTAR the aperture projections were reduced to 1.74" and 0.22" respectively. The small aperture projected to one resolution element, thus even pre-COSTAR data taken with this retained the as designed spectral resolution, albeit at reduced throughput.
Some data were acquired at time resolutions as short as 50 milli-seconds in a Rapid Readout mode. Most observations were acquired in accumulation mode which provided for oversampling, compensation for sensitivity variations along the Digicon array, and simultaneous monitoring of detector backgrounds. Routine observations of the on-board Pt-Ne emission line lamp provide data with well calibrated wavelengths.
The GHRS received about 20-25% of the total HST observing time over Cycles 1-6, with a large and diverse range of high quality science observations resulting. Due to the high signal-to-noise and large dynamic range capabilities in the far ultraviolet, much of this data will remain unique.
E. Instrument Handbook Changes
For each HST observing Cycle the Instrument Handbooks for all active science instruments will be updated and released. Since new versions of the Instrument Handbooks are mailed to individuals only upon request, we provide here a discussion of the changes made in the most recent version. The Instrument Handbooks themselves are also available via our Web server (see §2.2).
WFPC2 Instrument Handbook, v. 4.0, June 1996
The primary revisions to this version of the WFPC2 Instrument Handbook may be summarized as follows:
Observation Strategies: A new chapter (H§7) has been added specifically to assist observers in preparing Phase II proposals. Sections include: Observation of Faint Targets, Observation of Bright Targets, Observation of Faint Targets Near Bright Objects, Dithering Observations, Selecting Field-of-View Orientation, Polarization Observations, and Ramp Filter Observations.
Exposure Time Estimation: H§6 has been completely re-written. New material includes equations and shortcuts for signal-to-noise ratio (SNR) and exposure time calculation for point sources (both with PSF fitting and aperture photometry) and extended sources. A new Appendix gives representative SNR values for various exposures of stellar, power law, and emission line sources.
CCD Performance: Material on dark current and CTE (charge transfer error) has been updated.
Calibration: Material on UV throughput, dark current calibration, flat fielding, and impact of focus variations on photometry has been updated.
Other changes include addition of an index and acronym list.
FOC Instrument Handbook, v. 7.0, June 1996
The FOC Instrument Handbook contains new information in the following areas:
a. F/48 performance and availability. Problems with the F/48 kept it from being used in the previous cycles, however, recent tests have shown that the situation is improving so that the detector can be reliably used for science. As a result, the F/48 relay will be available AGAIN ONLY for long-slit spectroscopy in Cycle 7. The latest information describing the recent performance of the F/48 can be found in the new H§6.13.
b. Calibration accuracies. The results of the calibration activities have always been implicitly incorporated into each previous version of the handbook, however, a separate chapter (H§11) describes in more detail the present calibration program (H§11.1), along with the accuracy of the current calibrations (H§11.2). Chapter 11 also contains details on the current F/48 long slit calibration plan and expected accuracies.
c. Updated calibrations of the objective prisms. The dispersion curves for the F/96 objective prisms have been re-calibrated and the results are given in Table 5. In addition, analysis techniques and spectrophotometry accuracies are now provided in a new section (H§6.13).
d. Updated information on the performances of the Neutral Density filters. The in-flight transmission properties of the five neutral density filters available in the F/96 camera have been calibrated for the first time in Cycle 5, at optical and UV wavelengths. Details are contained in H§4.4.3.
e. New calibration of filter shifts. Most F/96 filters produce image shifts which can be as large as several pixels. These shifts have now been calibrated and the details are provided in H§4.4.3.
f. Updated information on FOC simulators. The FOC Instrument Handbook has always contained a chapter describing the software package FOCSIM, which was primarily accessible only through an account at the Institute. This chapter has been enhanced to describe the new software that has been added to determine the orientation of an FOC image on the sky. This software can be used either when planning an observation requiring a special orientation, or to determine the orientation of an image already obtained.
There are many other less significant changes throughout the handbook as well, but primarily they only served to update what was already present in earlier versions, rather than adding anything new.
FGS Instrument Handbook, v. 6.0, June 1996
The current new version of the handbook has been arranged in the following sections:
-instrument description
-instrument operation
-instrument performance
-instrument calibrations
-writing proposals
-data reduction
The section on instrument description has been expanded to include a more detailed discussion of the individual elements of the optical train of the FGS as well as the detailed workings of the Koesters prism interferometer.
The instrument calibration section has been updated to include some calibration data from Cycle 5.
The section on writing proposals has been expanded to include general guidelines and recommendations regarding observing strategies, exposure times, and Phase II special requirements and optional parameters.
The section regarding data reduction has been updated and includes references to the HST Data Handbook.
F. Target Naming Conventions
Target names are used to provide unique designations for the targets throughout the proposal. These names will generally also be used in Phase II, in the HST observing schedule, and ultimately to designate targets in the HST data archives. Prospective proposers and Archival Researchers will use these names to determine whether HST has observed a particular object. This facility will be most useful if consistent naming conventions are used for targets.
The following convention should be followed in naming targets:
Catalog Name
The preferred order for catalogs to be used for the designation of various classes of objects is provided below. It is arranged in order of decreasing priority. If a target is not contained in these catalogs, then other catalog designations may be used (e.g., IRC or IRAS Catalog numbers, 4U X-ray Catalog designation, Villanova White-Dwarf Catalog number, etc.). The use of positional catalogs (SAO, Boss, GC, AGK3, FK4, etc.) is discouraged. For uncataloged targets, see below.
Stars
1. Henry Draper Catalog number (e.g., HD140283). HDE numbers are discouraged, except in the Magellanic Clouds.
2. Durchmusterung number (BD, CD, or CPD). In the southern hemisphere, adopt the convention of using CD north of -525 and CPD south of that limit (e.g., BD+30D3639, CD-42D14462).
3. General Catalog of Variable Stars designation, if one exists (e.g., RR-LYR, SS-CYG).
Star Clusters and Nebulae
1. New General Catalog (NGC) number (e.g., NGC6397, NGC7027).
2. Index Catalog (IC) number (e.g., IC418).
3. For planetary nebulae, the Perek-Kohoutek designation (e.g., PK208+33D1).
4. For H II regions, the Sharpless Catalog number (e.g., S106).
Galaxies and Clusters of Galaxies
1. NGC number (e.g., NGC4536).
2. IC number (e.g., IC724).
3. Uppsala Catalog number (e.g., UGC11810).
4. For clusters of galaxies, the Abell Catalog number (e.g., ABELL2029).
Quasars and Active Galaxies
The name defined in the compilation by Veron-Cetty and Veron (ESO Report No. 13, 1993) should be used (e.g., 3C273).
Uncatalogued Targets
Objects that have not been catalogued or named should be assigned one of the following designations:
1. Isolated objects should be designated by a code name (the allowed codes are STAR, NEB, GAL, STAR-CLUS, GAL-CLUS, QSO, SKY, FIELD, and OBJ), followed by a hyphen and the object's J2000 equatorial coordinates, if possible, rounded to minutes of time and minutes of arc (e.g, for an optical binary star at J2000 coordinates a = 1**h 34**m 28**s d = -15531'12", the designations would be STAR-0134-1531A and STAR-0134-1531B).
2. Uncatalogued objects within star clusters, nebulae, or galaxies should be designated by the name of the parent body followed by a hyphen and a type designation of the object (e.g., for a star cluster within NGC 224, the designation would be NGC224-STARCLUS).
3. Known objects within nebulae or galaxies may also be designated by the name of the parent object followed by a hyphen and an identifier of the target object. The identifier should be brief, but informative (e.g., the jet in NGC 4486 could be designated NGC4486-JET). Other examples are: NGC5139-ROA24, LMC-R136A, ABELL30-CENSTAR, NGC205-NUC.
External Calibration Targets
The name of a target that is being observed only as a calibration standard for other observations should be designated by appending the code -CAL to the target name (e.g., BD28D4211-CAL). Internal calibration targets (e.g., WAVE, INTFLAT) and calibrations using the Earth should not be included in the OS, but in Item #13-Description of the Observations-of the proposal form.
G. Astronomical Symbols Available for Use
in the Proposal Templates
H. Starview Duplication and Archival Searches
The simplest and most robust way to determine whether your proposed observations conflict with previously accepted GO or GTO observing programs is to use StarView, the interface to the HST archive. Within StarView users will find a Duplication Check Screen which they can use to perform RA and Dec based or target name based searches of all planned or completed HST observations. Searching by RA and Dec is the only reliable way to find duplications of fixed target observations. Target names do not fit a fixed standard, and can vary from proposal to proposal. Solar system observations should be found by target name, imbedded in asterisks, e.g., *Mars*. Data browsing (display of images and plotting of spectra) is available for all public HST data in the archive. Archival proposers will also find the Duplication Check screen useful for preparing their archival proposals.
StarView is a software package that can be installed on your computer. However, StarView can also be accessed via telnet to one of the two archive host computers, archive.stsci.edu (unix) or stdata.stsci.edu (VMS). If you are not a registered archive user, log in with username guest and password archive. You do not need to register as an archive user to do duplication checking or to browse the data. You need to register as an archival user only if you wish to retrieve public HST data. For those who wish to retrieve data, registration is a simple process- just type register from the command line on one of the host computers.
To begin simply type xstarview to fire up the xwindows based version of StarView (if StarView is not able to create the window on your screen you should contact your local System Manager to have necessary permissions set), or type starview to use crt StarView. While there is extensive help available within StarView (via the Strategy button and the pull down Help menu), xstarview is fairly intuitive. When StarView starts up, it places you in the Welcome Screen. Select the <Duplication Check> button from the bottom (command) portion of the screen, by clicking with the mouse on the xversion or entering Esc-2 on the crt version. This will place you in the "Duplication Check Search" screen. To search for observations of a specific fixed target, enter the RA and Dec in J2000 coordinates of the target and a search radius. If you know only the name of your fixed target, but not the coordinates, select the <Get Coordinates> button and enter your source name; the software will then connect to the SIMBAD (Set of Identifications, Measurements, and Bibliography for Astronomical Data) database or the NED (NASA Extragalactic Database) to determine the coordinates of your source. To search for observations of moving targets, specify the target name embedded between asterisks (e.g., *JUPITER*) in the target name field on the "Duplication Check Search" screen. You can also enter specifications in any of the other fields to further constrain your search. When you are ready, select <BEGIN SEARCH> from the command area. (Note: The duplication checking screen allows you to check targets one at a time or to cross correlate a list of target RA and Decs against the catalog all at once. You can employ the latter capability by selecting the <Cross Correlation> button from the command area of the "Duplication Check Search" screen. More information about the cross correlation capability is provided as part of the Strategy for the "Duplication Check" screen).
If a planned or completed HST observation is found which matches your search criteria, the screen will change to the "Duplication Check Results" screen where more detailed information about the matching observation will be displayed. You can step through matching observations one at a time by using the <Step Forward> button, or you can use the <View Result as Table> button to display the information in tabular form and step through the matching observations a page at a time. Completed observations (i.e., those having exposure status = "completed") which are public (with release dates less than the current date) can be previewed using the <Preview> button.
The duplication checking screen is designed only to identify potential conflicts; you will have to decide whether the apparent conflicts are "real". The formal duplication policy is described in §6.1. Proposed observations which duplicate any existing or planned observations must be justified in the Proposal. In particular proposed observations which conflict with GTO Cycle 7 targets, which are not specifically endorsed by the TAC, will be disallowed or restricted during Phase II checking. Planned exposures of GTO Cycle 7 targets are identified by conflict type = "GTO" and exposure status = "planned - cycle 7".
Abstracts of all proposals which have been approved for observation (including both executed and pending proposals) can be displayed using the "Abstracts" screen in StarView. This screen can be accessed via the <Other Searches> button on the "Welcome Screen" of StarView or by pulling down the "Searches" menu, in the menu bar on the top of the screen. The "Abstracts" screen is listed in the "Observation/Proposal Searches" submenu, as part of the "Archive Searches" menu. Enter the proposal id of the proposal whose abstract you wish to view, or qualify on proposal title to search for proposals of a particular type of object (e.g., type *SEYFERTS* in the title field). Push <BEGIN SEARCH> when you are ready. To find observations of a particular class of object you can also use the "General Screen" and qualify on the target description field in this same way.
More information about StarView and the HST Archive is provided in the Archive Primer. For help, documentation, or information about any aspect of the HST Archive, contact the archive hotseat (e-mail archive@stsci.edu or phone 410-338-4547).
In light of these considerations, the STAC recommended for Cycle 7:
These recommendations have been incorporated into this Call for Proposals. Additional details of the STAC deliberations, including the STAC report, can be found through the STScI Web page or the STScI Newsletter.
J. Continuous Viewing Zone Tables
The tables in this Appendix will be useful for proposing observations that can take advantage of Continuous Viewing Zone (CVZ) observing (see §14.1). Included are three tables for each of northern and southern declinations for a six-month sample period:
1. the maximum duration in orbits of any single CVZ interval, and
2. the total duration in orbits of all CVZ opportunities for targets at the specified RA and Declination,
3. the total number of CVZ intervals.
The sample period for these tables was taken to be July 1997 through June 1998. Proposers should be aware that near the "wings" of the CVZ area (i.e., where there is only one CVZ interval), the actual availability of CVZ observing will depend in detail on the geometry of the HST orbit during Cycle 7.
(Tables are attached on the following pages, pp. 77-82.)
K. Examples and Blank Worksheets
This appendix contains example orbit calculations and blank "worksheets" for each instrument, that can be used to help lay out the exposures and overheads needed to calculate the number of orbits required. Detailed instructions for how to make the calculations are provided in §18. Note that these worksheets are not for submission with the Phase I proposal, but are strictly for your convenience for calculating the number of orbits.
(Worksheets are attached AFTER the CVZ tables, pp. 83-100.)
L. Blank Budget Forms
The following blank forms are provided:
(Forms are attached AFTER the worksheets, pp. 102-107.)
AR Archival Research
AURA Association of Universities for Research in Astronomy, Inc.
CADC Canadian Astronomy Data Centre
CCD Charge-Coupled Device
CDB Calibration Data Base
Co-I Co-Investigator
COSTAR Corrective Optics Space Telescope Axial Replacement
CVZ Continuous Viewing Zone
DADS Data Archive and Distribution System
DD Director's Discretionary
DUP Duplicate Observation
ESA European Space Agency
FGS Fine Guidance Sensor
FITS Flexible Image Transport System
FOC Faint Object Camera
FOV Field of View
FOS Faint Object Spectrograph
ftp File Transport Protocol
FUV Far Ultraviolet
GASP GSSS Astrometric Support Package
GHRS Goddard High Resolution Spectrograph
GO General Observer
GS Guide Star
GSC Guide Star Catalog
GSFC Goddard Space Flight Center
GSSS Guide Star Selection System
GTO Guaranteed Time Observer
HSP High Speed Photometer
HST Hubble Space Telescope
IDC Indirect Cost
IDEA Initiative to Develop Education through Astronomy
IDT Image Dissector Tube
IRAF Image Reduction and Analysis Facility
JPL Jet Propulsion Laboratory
LRF Linear Ramp Filters
MAMA Multi-Anode, Microchannel Array
MT Moving Target
NASA National Aeronautics and Space Administration
NED NASA/IPAC Extragalactic Database
NICMOS Near Infrared Camera and Multi-Object Spectrometer
NOAO National Optical Astronomy Observatories
NUV Near Ultraviolet
OA Operations Astronomer
OPUS Observation Support/Post-Observation Data Processing Unified System
OS Observation Summary
OTA Optical Telescope Assembly
PAR Parallel Observation
PC Planetary Camera
PCS Pointing Control System
PI Principal Investigator
PMT Photomultiplier Tube
PRESTO Project to Re-Engineer Space Telescope Observing
PSF Point-Spread Function
RPS2 Remote Proposal Submission 2
SAA South Atlantic Anomaly
SHD Shadow Time
SI Scientific Instrument
SIMBAD Set of Identifications, Measurements, and Bibliography for Astronomical Data
SMOV Servicing Mission Orbital Verification
SMS Science Mission Specification
SM97 Second HST Servicing Mission, Scheduled for February 1997
SOS Science Operations Specialist
SPSO Science Program Selection Office
SSM Support Systems Module
ST-ECF European Coordinating Facility for Space Telescope
STAC Space Telescope Advisory Committee
STEIS Space Telescope Electronic Information Service
STOCC Space Telescope Operations Control Center
STIS Space Telescope Imaging Spectrograph
STScI Space Telescope Science Institute
STSDAS Space Telescope Science Data Analysis Software
TAC Telescope Allocation Committee
TDRS Tracking and Data Relay Satellite
TDRSS Tracking and Data Relay Satellite System
TOO Target of Opportunity Observation
TIM Telescope Image Modelling
URL Universal Resource Locator
WFC Wide Field Camera
WF/PC Wide Field and Planetary Camera (1)
WFPC2 Wide Field Planetary Camera 2
WWW World-Wide Web