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Space Telescope Users Committee
May 1998

The Space Telescope Users Committee (STUC) met in open session on 18-19 May 1998, in the Board Room of the Space Telescope Science Institute. Committee members in attendence were: B. Balick, J. Bally, J. Clarke, L. Kay, P. McCarthy, F. Mirabel, R. Schulte-Ladbeck, S. Terebey, R. Thompson, F. Walter (Chair), H. Weaver, and B. Woodgate. Absent were R. Fosbury, J. Frogel, and S. Ortolani.

Minutes of the meeting are reported elsewhere.

Readers should note that this report is based on information presented to the STUC in May 1998, and may be superceded by later developments. Readers are urged to refer to the STScI web pages for up-to-date information.

Executive Summary

The tenor of this meeting was generally positive. HST continues to operate well. NICMOS is performing as advertized. The NICMOS Cooling System is looking more practical. Plans for SM3 are advancing towards a May 2000 mission. The projected funding for the HST project looks good through 2010, to the extent that any budgetary projections can be believed. NASA and the STSCI are beginning to plan how to operate HST at low cost after 2003. And a new director has been appointed to lead STScI into its second decade.

The personnel at NASA Headquarters who manage space science programs were delighted that Congress recently listed "science" as NASA's top priority, and this new emphasis creates optimism for the future of space science endeavors at NASA, although the imminent departure of Wes Huntress, who has beeen an effective advocate for science at NASA, does create some uncertainty.

However, the committee had a number of concerns about the adverse impacts caused by the apparent inadequate staffing of STScI on the capabilities of the HST. The committee expressed concerns about perceived imbalances on various review panels and committees. And the performance and calibration status of the ACS continues to be a concern.

The Second Decade Study

It is clear that NASA is serious about continuing to operate HST through 2010, and the STUC enthusiastically supports this. NASA has convened the Second Decade Study to recommend how to best utilize the HST in an era of reduced support, and in concert with a new array of supporting technologies, including AXAF, XMM, SIRTF, SOFIA, NGST, GEMINI, and the VLT. Although purview of the Second Decade Committee is somewhat limited because the final instrument complement is set, it has the charge and responsibility to develop observing strategies for HST to maximize its scientific potential in the context of changing programmatic needs.

The STUC is concerned that the Second Decade Committee is inappropriately constituted to meet this challenge. The STUC feels that a committee which lacks sufficient breadth to appeal to the full astronomical community will not gain the respect of the full community, and that its recommendations may not be taken seriously. HST will need broad support from the community to continue to operate during this second decade.

The STUC has delivered a brief report to the Second Decade Study Committee. We are heartened that the committee membership has been augmented in reponse to some of our concerns.

STScI Manpower

A number of instrument capabilities, particularly on STIS, are not yet implemented. This is directly attributable to manpower limitations. We encourage a review of the distribution of reponsibilities, in the expectation that this could lead to an enhancement of the resources available for instrument, observer, and operations support.

Proposal Evaluation

The information content returned to the proposers from the Cycle 7 archival research proposal reviewers was far superior to the checklist used during the Cycle 7 delta CP. Reviewers thought that the checklist was a good tool for internal use, but the proposers felt that it failed to convey any sense of the rationale for the decisions. We encourage STScI to retain written reviews for Cycle 8. We urge the STScI to instruct the reviewers to put themselves in the place of the proposers, and to write a review sufficiently detailed that proposers will understand why their proposals were so evaluated.

The STUC noted some apparent problems with the Cycle 7 delta-CP and archival research reviews. In the Cycle 7 delta-CP review, proposals targeting star formation and circumstellar disks were spread over two panels, neither of which appeared to have much expertise in this area. Consequently, a surprisingly small number of orbits was allocated for star formation studies, despite the excellence of NICMOS for tackling problems in these areas. Similarly, a lack of panelists with expertise in spectroscopy of cool star chromospheres and coronae may have contributed to the lack of successful proposals in this area in the Cycle 7 AR CP.

The greater number of panels (and panelists) in the Cycle 7 review led to a fair treatment of these and other scientific areas. We are cognizant of the difficulties involved in assembling review panels, and we understand the difficulty of providing experts in all possible fields for the smaller supplemental reviews, but we urge the STScI to make a strong effort to ensure fairness and balance in the review process.

Archive Users Survey

The STUC generally concurs with the conclusions and recommendations of the 1998 Archive Users Survey. The STUC is enthusiastic about the plans to implement the On-The-Fly-Calibration system. We agree that paper products are important, but that the number of pages produced could be reduced, especially in cases (like NICMOS) where the typical observation has hundreds of observations.

HST Scheduling

The experience of Cycle 7, with the unforeseen difficulties with NICMOS mandating the delta-CP, is one we would all like to put behind us. For GOs and the STIS GTO team, the deferral of STIS and WFPC2 observations into 1999 has, in many cases, caused both scientific and financial hardship. At the urging of this committee, the archival Call for Proposals (CP) was issued to provide users of the archive an interim opportunity independent of the drawn-out observing cycle. The STUC thanks the STScI and the HST project for their responsiveness. The STUC realizes that these unplanned CPs involved much effort, and applauds all involved in successfully implementing these extraordinary calls for proposals.

The STUC welcomes the return to 1 year durations for Cycles 8 and 9. We look forward to predictability in the dates of future cycles, and strongly support the objective, being pursued by the STScI, of creating a stable Long Range Plan.

Planetary Working Group

The new capabilies for planetary and moving target observations (discussed in the minutes) continue to be important for the production of high quality science from HST. The STUC encourages STScI to continue the development of these capabilities. In particular, we believe that the routine distribution of finding charts to observers will be valuable in heading off pointing problems, which have plagued observations in the past, before they occur, thereby also improving observing efficiency.

There is a specific problem with some observations using track 51 tracking. Often, in a sequence of exposures using different filters, apertures, etc., the absolute pointing within the field of view is crucial for the comparison of the exposures. However, the present software creates a new alignment with a new pointing, differing typically by 1-2 arc sec in some random direction, whenever any of a series of parameters is changed in the phase 2 proposal, including the aperture, target name, etc. In the case of STIS, several different filters have unique aperture names defined for them. It is not possible in the phase 2 proposal to obtain co-aligned images, for example, with the UV-MAMA clear and with any filter, since each of these exposures is required to be performed with a different aperture name. We request that the STScI look into this matter, modify the ground software to enable co-aligned observations under track 51, and report back to this committee.

The Proliferation of Committees

There are many committees and ISRs advising STScI and the HST project these days. These committees are often called into existence to examine a single narrow aspect of the HST operations. The STUC, as the standing committee representing the interests of the users of the HST, is concerned that these committees and ISRs may not understand the history and context of the actions, and its impact upon the HST users. We request that the STUC be informed of the creation of such committees and ISRs, and that the STUC be represented on these committees, either through explicit membership or in an ex-officio manner.

Advanced Camera for Surveys

The STUC remains concerned about the status of the ACS. It is clear that fiscal issues are compromising the ACS ground testing and calibration programs, particularly in regards to the solar blind camera (SBC). We strongly advise the project to aggressively seek ways to provide the appropriate resources for this very important effort. The HST project should not jeopardize the long-term scientific potential of the ACS due to a short-term financial problem.

The STUC was told that the typical GO data set from an ACS observation would total nearly 9 Gb, and would require a high-end workstation to process and analyze. We trust that this need will be taken into account when grants for projects involving ACS data are awarded.

The NICMOS Cooling System

It is clear to the committee that NASA is pursuing a cautious approach to the NICMOS Cooling System (NCS; formerly the cryocooler). If the NCS can extend the useful scientific life of the NICMOS, with no adverse impacts upon the safety or operational capabilities of the HST, this committee endorses the concept.


The STUC endorses NASA's plan to replace the aging WFPC2 with a new and more capable camera, presently known as WFC3. The straightforward design approach helps to insure the presence of an important research tool of low cost and high value intended primarily (but not exclusively) for galactic studies that can complement the Advanced Camera. The WFC3 will be an exciting instrument for the second decade of HST operation, especially for narrow-band imaging of emission-line regions, including H-H objects, all sorts of ionized stellar outflows (e.g. LBVs, supernovae, post-AGB stars), and the ejecta from relatively-low-redshift AGNs. In tandem with STIS, WFC3 will be the premier tool for studying gas morphologies and kinematics in many types of objects.

The WFC3 will be a popular user instrument, but its realized scientific utility will be very sensitive to the selection of its filters. STUC applauds the plans for community wide-study of the filters (to be conducted by the WFC3 Scientific Oversight Committee now being organized). The STUC urges that the HST project see to it that the scientific oversight committee is balanced between galactic and extragalactic interests. The STUC wishes to be appraised of the selection of filters prior to the selection being finalized. We suggest that a member of the STUC be appointed to the SOC in either an active or ex-officio capacity.

Given that the current design of the WFC3 draws more on the heritage of the ACS than it does on the WFPC, we concur with the suggestion that NASA seek another name for this instrument.


The STUC applauds the proposed acceleration of the funding of HST grants, which is one goal of the Grants Administration Team for Organizational Reengineering (GATOR) project. However, we are concerned that the funding algorithm will be too general to adequately account for the disparity of budgetary needs. Judgment of the complexity of the data reduction and analysis, and of the funding needed, should ultimately remain in the purview of the PI. Observers must not be penalized for working at high-overhead institutions, nor for living in regions with high costs of living and salaries. The STScI must realize that graduate students can rarely be employed for periods shorter than a semester or a summer, and that PI summer salaries should be allotted in units of man-months. The STUC also feels that the Grant's Office's projection that only 10% of the PIs will appeal is on the low side.

The STUC looks forward to the report, in a year's time, detailing how accurately the funding algorithm predicts the requested budgets during Cycle 8.

The Director

With deep admiration and gratitude the STUC recognizes the many scientific and administrative achievements made by the outgoing Director of the STScI, Dr. Robert E. Williams. Bob kept a steady hand on a large, successful, and high-momentum organization during times of financial havoc and staff reductions early in his tenure. The Institute emerged leaner and meaner, and it has maintained a record to be admired by the entire astronomical community.

HST users have benefitted from Bob's commitment to a simplified proposal process, his strenghtening of staff orientation to user requests, and his continuous enthusiasm for new HST instruments and initiatives. All during this time Bob maintained an active research program, most notably contributing in many important ways to one of the premier astronomical experiments of the 20th century: the Hubble Deep Field. The STUC has always found Bob to be an engaged listener, a forthright, dependable, and enthusiastic partner, and an always-cheerful sport in the parrying that characterizes STUC meetings.

We wish Bob Williams an active, productive, successful, and satisfying return to a life outside the Director's Office, and we look forward to equally good relations with the new director.

This report submitted by Frederick M. Walter

on behalf of the Space Telescope Users Committee

July 1998