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Late Breaking NewsMarch 04, 2008: 4:42PM ETC Problems Solved The problem that caused the HST instrument ETC proxy server to hang on Tuesday, March 4 has been identified and fixed. The ETCs are currently functioning as expected. March 03, 2008 COS Handbook Update An error has been found in Chapter 7 of the COS Instrument Handbook, which discusses acquisitions. Specifically, the exposure times needed for a successful acquisition are longer than those illustrated in Figure 7.3. We anticipate that in almost all cases this error will not affect the time needed in a Phase I proposal because the total time needed for an imaging acquisition with COS is still very short. Nevertheless, if the time needed to acquire a source is of concern, proposers are urged to use the COS Exposure Time Calculator to estimate the correct acquisition time. March 03, 2008 WFC3 buffer management The description of buffer management in Section 10.3.1 of the WFC3 Instrument Handbook (p. 156 paragraph 5 -p. 157 paragraph 2) is replaced by the following: Parallel dumping of the WFC3 buffer The WFC3 buffer provides temporary storage of images read from the WFC3 detectors before they are dumped through the HST science data formatter (SDF) to the solid state recorder (SSR). The buffer can be dumped either between exposures (a "serial" dump), or during an exposure (a "parallel" dump), but cannot overlap any commands executed in WFC3, including the commands at the beginning, or end of an exposure. The buffer may be dumped during pointing maneuvers, but not during acquisition of guide stars. The buffer may be dumped during target occultation, which does not deduct from the target visibility time. Switching channels (IR and UVIS) does not require dumping the buffer. Observers will generally prefer to use parallel dumps, in order to more fully utilize the time when a target is visible for science exposures. The rules for dumping the buffer in parallel with UVIS exposures differ in some respects from those for dumping in parallel with IR exposures. The two channels are considered separately in the following paragraphs. UVIS parallel buffer dumps The buffer can hold up to two full-frame UVIS images. A single full-frame image can be dumped in parallel with a UVIS exposure greater than 347 seconds and two full-frame images can be dumped in parallel with a UVIS exposure greater than 663 seconds. When the buffer is dumped, all stored images must be dumped. Consequently, a sequence of 348-second (or, longer) exposures will incur no overhead for dumping the buffer. Whether a sequence comprised of short exposures (less than 348 seconds) and long exposures (greater than 347 seconds) will require serial buffer dumps will depend upon the order of the long and short exposures and the duration of the long exposures. Dumping the buffer during a sequence of short and long exposures will be more efficient if the long exposures are 664 seconds (or longer). For example, an orbit with exposures with exposure times in the sequence 10-348-10-664-10-664-10 will incur no serial dump penalty. The observer will plan such sequences with APT in Phase 2. Sequences of full-frame, un-binned exposures less than 348 seconds will require the overhead of serial buffer dumps. For short exposures, using sub-arrays or binning may be advantageous in order to reduce the overhead of serial buffer dumps. The time to dump a sub-array or binned exposure scales approximately with the number of pixels stored in the buffer. IR parallel buffer dumps The buffer can hold up to two full-frame, 15-sample IR images. To dump one such image in parallel with an IR exposure requires that exposure to be longer than 348 seconds. To dump two such images requires an exposure longer than 646 seconds. The rules for dumping IR exposures differ significantly from those for dumping UVIS exposures, being less restrictive. For purposes of dumping IR exposures, each sample is treated individually; all samples in the buffer are not required to be dumped together; and samples can be dumped during the non-destructive read of the FPA. Sequences of full-frame, 15-sample exposures shorter than 349 seconds will require serial dumps after the second and subsequent exposures. Sequences of longer-exposure (i.e., greater than 348 seconds), full-frame, 15-sample exposures will incur no overhead for dumping the buffer. Sequences comprised of short (less than 349 seconds) full-frame, 15-sample exposures and long exposures (greater than 348 seconds) may incur overhead for serial dumps, depending upon the sequence of exposures and the duration of the long exposures. The observer will plan such sequences with APT in Phase 2. The time to dump an n-sample, full-frame exposure is approximately 39 + 19*(n+1) seconds. Sub-arrays may also be used to reduce the overhead of serial buffer dumps. March 03, 2008 Advice on using ACS and WFC3 in parallel PIs who are proposing Cycle 17 observations with WFC3 and ACS/WFC used in parallel may be interested in the following information on how exposures may be packed in to a typical orbit. Details will vary depending on the specifics of the individual programs, but as an example, consider a 1 orbit visit targetting an object at declination 45 degrees (3400 seconds visibiity) and that aims to combine WFC3/UVIS/F814W imaging with ACS/WFC/F814W in parallel. Guide star acquisition requires ~350 seconds, leaving 50 minutes for exposure and exposure overheads. The following options run successfully through APT version 17.0.2, and should be amenable to minor modifications: 1) WFC3 3x850s + ACS 3x800s (sets of 3 shorter exposures also work) 2) WFC3 2x400s+2x800s + ACS 2x400s+2x800s (best packing for 4 exposures) (ordering is 400,800,800,400 for both instruments) 3) WFC3 4X450s + ACS 4X450s (somewhat inefficient compared to #2) 4) WFC3 2x1300s + ACS 2x1300s (very efficient) Option #2 gives ~2400 sec of exposure time with each instrument. Option #4 gives 2600 sec of exposure time with each instrument. Both options are very efficient and powerful. Switching filters during the orbit incurs only a minor overhead, so the above sequences (with slightly reduced times) should provide suitable options. February 28, 2008 COS GTO and WFC3 ERS Duplication Checking The COS GTO and WFC3 ERS programs were inadvertently not included in the duplication checking web page and the Planned and Archived Exposure Catalog. An Exposure Catalog for the GTO and ERS programs is linked as an excel spreadsheet from both the COS GTO and WFC3 ERS webpages. Proposers of COS or WFC3 programs should use this Catalog for additional duplication checks. February 28, 2008 SNAP programs for Moving Targets For safety reasons, SNAP proposals to observe moving targets are not permitted to request observations with photon counting detectors (i.e. ACS/SBC, STIS/MAMA and COS). February 28, 2008 Pure Parallel Program Large Requests It has been noted that the Call for Proposals didn't address what was considered a Large Pure Parallel Request. We have decided that any request of 100 orbits or greater for Pure parallel programs will be considered large and has the same page limits as Large GO programs, ie 11 total pages with 6 for the Science Justification. February 27, 2008 CVZ Tables no longer available on Proposer Web pages CVZ tables are no longer available on the website. You must use APT to determine your CVZ schedulability windows. February 18, 2008 NASA Updates Shuttle Target Launch Dates for Servicing Mission 4 February 14th, NASA updated the remaining 2008 Space Shuttle Target launch Dates including Servicing Mission 4. February 18, 2008 Scientific Category Pull-Down Error in APT 17 In the release of APT 17.0 an error in the Scientific Category Pull-Down was created. In the Planetary Systems and Star Formation Pull-Down, the value of "Circumstellar Disks" was included by mistake. Please do not select "Circumstellar Disks" as a Scientific Category. This has now been fixed with APT Version 17.0.2. Please download the new version of APT. February 1, 2008 Multi-Cycle Treasury Programs Late last year, STScI issued a call for white papers on the potential scientific impact of multi-Cycle Treasury Programs. A total of 22 papers were received, and reviewed by a small ad hoc committee. On the basis of that committee's report, the Director of STScI has decided to explore means of implementing this new type of program. The full scope of the new program and the associated time allocation process will be developed in consultation with the Space Telescope Users Committee and the broader community. However, the following factors are relevant to Cycle 17: 1. Multi-Cycle Treasury Proposals will be assessed separately from standard HST proposals. The Call for Proposals will not be issued until after SM4 is completed and the on-orbit performance of each instrument has been verified. It is likely that the MCT proposal submission deadline will be in early 2009, 2-3 months before the Cycle 18 deadline. There is no requirement for a precursor proposal in Cycle 17. 2. Our baseline assumption is that any successful MCT programs will be scheduled in Cycles 18 and 19; consequently, we do not anticipate adjustment to the overall orbit allocation for Cycle 17. 3. As described in the Cycle 17 Call for Proposals, proposers have the option of submitting Large or Treasury Programs that are multi-cycle. This option has been available in previous cycles. We will ask the Cycle 17 TAC to select programs based solely on scientific criteria. However, the TAC members will obviously be aware of the future opportunity to submit MCT Programs. For further information, please contact Neill Reid, inr@ststci.edu January 17, 2008 APT 17.0 Has been Released for Cycle 17 Phase I Proposers APT version 17.0 is now available for download from the apt web page: hhttp://www.stsci.edu/hst/proposing/apt January 10, 2008 WFC3 Instrument Handbook error correction It was reported last week that the IR filters throughput figures were not in-sync with synphot. It turns out that we had the current files on hand, but the figures were somehow not linked properly in the document. The correction to the figures 7.2 and 7.3 in the WFC3 Instrument Handbook have been done now. There is a new page in the "News" section of the website documenting this correction. http://www.stsci.edu/hst/wfc3/documents/handbook/ihb_errata.html Both, the html and pdf versions of the WFC3 Instrument Handbook have been corrected. December 14, 2007 HST Phase I Deadline published incorrectly by AAS Calendar The AAS Calendar that was distributed to members for 2008, has an incorrect date for the HST Phase I Deadline. The correct date, is March 7, 2008 as posted on our website, not the 17th as printed in the calendar. We are sorry for the confusion this might have caused. December 03, 2007 COS GTO Program The Cosmic Origins Spectrograph (COS) Science team has been allocated 555 orbits for Guaranteed Time Observations (GTO). (Four orbits have already been expended on observations with ACS.) GTO programs are protected against duplication by General Observers (GOs). Individual observations can be checked for GTO duplications using tools provided by the HST Data Archive. COS GTO data have a 12 month proprietary period. A summary of the GTO programs that will be implemented in Cycle 17 can be found at: http://www.stsci.edu/hst/proposing/docs/COS-GTO. The GTO and ERS Exposure catalog is available on this page for Duplication checking. December 03, 2007 WFC3 ERS Program The Wide Field Camera 3 (WFC3) Science Oversight Committee has been allocated 214 orbits of Directors Discretionary time to carry out an Early Release Science (ERS) program, "Star formation, near and far". The observations are protected against duplication. However, the data are non-proprietary, and GOs can propose supplementary observational programs that build on the WFC3 ERS observations. A summary of the WFC3 ERS program can by found at: http://www.stsci.edu/hst/proposing/docs/WFC3-ERS. The GTO and ERS Exposure catalog is available on this page for Duplication checking. December 11, 2007 COS and WFC3 Handbooks and ETC Update The COS and WFC3 Handbooks are now available in HTML and PDF from the Instruments Page. The ETCs for all instruments are also planned for an update on December 17, 2007. If you use the ETCs prior to that time, please return and verify your results after the updates have been made. |
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