THE HST OBSERVATORY From the Director's Office After a prolonged period of commissioning and early science observations, the Cycle 1 General Observer (GO) and Guaranteed Time Observer (GTO) science programs have begun. In May, responsibility for constructing the science mission of HST was transferred from NASA to STScI. While many of the formal Science Verification calibration programs will be completed in the next six months under NASA coordination, this formal transition was a natural and important step in the HST mission. Both the ground elements at GSFC and science mission operations at the STScI have proven their capability to operate the spacecraft in a routine fashion as well as to recover from unforeseen problems. Currently, astronomical observations are being defined months before their execution in order to improve the efficiency of telescope usage and to coordinate satellite communications with other NASA facilities. However, for scientific targets of opportunity and unforeseen difficulties, the GSFC and STScI systems have been able to respond rapidly and with a minimum impact upon the preplanned science program. A recent example was the response to a failed flight-computer memory board, which led to a deep safing of the observatory and loss of communications. As described in Rodger Doxsey's article below, the controllers were able to restore normal operations within five days - just in time to initiate a time-critical science observation of the flare star AD Leonis carried out in coordination with ROSAT! As the first cycle of science observations begins, members of the astronomical community are already preparing their proposals (including proposals for Archival Research) for Cycle 2, which will start in July 1992. Although Cycles 2 and 3 will not enjoy the improved imaging that we expect to obtain later when the corrective optics are installed, we do anticipate that these new programs will be better matched to the HST's current optical performance. Over one hundred astronomers participated in the May HST Workshop: "The Year of First Light." During the workshop, dozens of scientific and technical presentations made it clear that our understanding of the observatory and its scientific capabilities was markedly better than earlier this year. Both the GTO and Cycle 1 GO programs have been completely revised; and a new catalog of approved observations has been mailed to the community in advance of the July 31/August 16 deadlines for Cycle 2 proposal submissions. Despite the excellent work that has been reported and the new and exciting observations to be taken over the next 2-3 years, the presentations at the HST workshop reinforced the scientific importance of restoring HST's performance at the earliest possible opportunity. We are encouraged by the successful review of the COSTAR design, a major milestone, and the continuing development of the WF/PC replacement instrument. And we are grateful for the recent resolutions of the AURA Board of Directors in this regard: "The AURA Board of Directors commends the STScI staff and its Director for initiatives taken in response to the problems encountered in the HST mission. STScI has effectively represented the interests of the astronomical community in maximizing scientific returns with the current HST capability, in refashioning the observing program, and in devising and advocating solutions to restore the full HST capabilities. "The AURA Board reaffirms the importance of effective STScI involvement in decisions regarding the design, development, calibration, and operation of the advanced scientific instruments for HST. We encourage the STScI, because of its skills and experience, to continue to engage the participation of the community in the definition of the design and operation of future ultraviolet, optical, and near-infrared observational facilities in space." To begin the process of looking beyond the next three years and the first maintenance mission, we intend to invite members of the scientific community, spacecraft engineers, and representatives from NASA to engage in a series of wide-ranging discussions on how best to shape the long-term HST mission. Two new scientific instruments, the Near Infrared Camera (NIC) and the Space Telescope Imaging Spectrograph (STIS), are already being developed to replace some of the existing instruments in 1997. But issues such as the need to reboost the spacecraft before the next solar cycle and the need to maintain adequate flexibility to respond to future problems are quite complex. As for all difficult and worthwhile enterprises, we cannot predict how these discussions will be resolved. But we are convinced of their importance and the critical role that an informed and involved scientific community must play in the life of HST. -Peter Stockman & Riccardo Giacconi HST Spacecraft Operational Status On April 3, the HST pointing-control software was updated in an attempt to counteract the jitter induced by thermal fluctuations in the solar panels, which occur following terminator passages. Although the software update has not eliminated the jitter, it has substantially reduced the jitter amplitude (by about a factor of 2), which in turn has significantly reduced the incidence of loss of guide- star lock associated with terminator crossings. The remaining jitter will produce some degradation of data taken during terminator passage, and STScI is currently examining the seriousness of this on an instrument-by-instrument basis. If it seems desirable, STScI will propose changes to the ground system that would provide the option of scheduling observations to avoid the periods when these disruptions occur. On May 2 at 14:43 (EDT) the HST spacecraft unexpectedly went into a safemode condition governed by a special electronics assembly that takes control whenever a serious defect is detected either in the DF224 flight control computer or in the HST power systems. In this condition, (known as "hardware sunpoint safemode") the telescope aperture door is closed and the telescope and solar arrays are slewed to place both perpendicular to the Sun. The scientific instruments and other equipment were also placed into a safe low-power configuration. The spacecraft properly executed all the steps involved in reaching a safe configuration. At the time of this event, HST was in a part of its orbit where it was out of contact with the Tracking and Data Relay Satellite System (TDRSS). Contact was re-established and analysis of the cause of the safing began. Within a day it was evident that the most likely culprit was memory unit #3 of the DF224, and plans were made to reconfigure the computer to use one of the two spare memory units in its place. The DF224 has a total of six memory units, of which four are required for normal operations and two were onboard spares. By the morning of May 5 the DF224 had been reconfigured, diagnostic programs successfully executed, and the process of safemode recovery begun. STScI prepared Science Mission Specifications (SMSs) for the recovery of the scientific instruments and to intercept the observing program on May 7. The recovery went as planned and HST operations returned to normal. An investigation into possible causes for the memory failure has begun. -Rodger Doxsey HST Science HIGHlights Special HST Issue of Ap. J. Letters The March 10, 1991, issue of Astrophysical Journal Letters was devoted to a series of papers presenting the first scientific results from HST. A total of thirteen papers discussed the imaging performance of the telescope, and presented a wide variety of initial results in solar-system, stellar, and extragalactic astronomy. HST Results Presented at May Workshop This year's STScI Workshop-"The Year of First Light"-was held at the Institute on May 14-16. It was devoted to 29 presentations of the latest scientific results from the HST mission and updates on the spacecraft and instrument performance, and was attended by over 100 astronomers. Several speakers emphasized that the spacecraft, telescope (aside from the primary mirror's spherical aberration), and scientific instruments are operating extremely well. Space does not permit discussion of all of the scientific results here, but among the highlights were the following: n WF/PC observations of Mars, Jupiter, Saturn (during its recent storm event), and Titan n high-resolution imaging of the cores of two globular clusters n high-resolution spectroscopy of stellar-wind and interstellar features in the spectra of galactic and Magellanic Cloud hot stars, and of chromospheric and coronal emission lines in cool stars n imaging and spectroscopy of circumstellar features in R Aquarii, b Pictoris, h Carinae, and SN 1987A n imagery and spectroscopy of active galactic nuclei, jets, and gravitational lenses n discovery of a low-redshift Lyman-alpha "forest" in the UV spectrum of 3C 273 Thanks go to the Scientific Organizing Committee (Chris Blades, Albert Boggess, Mike Fall, Riccardo Giacconi, David Leckrone, Colin Norman, and Pete Stockman) for a most interesting workshop, which demonstrated that a flood of exciting new science from HST is only just beginning. -Howard E. Bond GHRS Observes chi Lupi The remarkable power of HST's Goddard High Resolution Spectrograph (GHRS) to provide entirely new information about the compositions and physical properties of stars and other objects is illustrated by observations of the chemically peculiar star c Lup, obtained in February. This star is known from ground-based observations to be rich in several normally rare chemical elements. For example, its atmosphere contains 100,000 times more mercury and 10,000 times more platinum per unit volume than does the Sun. c Lup is a moderately hot star, with a surface temperature of about 11,000 K. The GHRS spectrum was obtained in the echelle mode (resolving power 87,000), through the Small Science Aperture, so that the resolution was unaffected by the spherical aberration. The signal to noise (S/N) ratio per data point in the continuum is about 100. The first illustration, on the facing page, compares a section of the GHRS spectrum with the corresponding section of the best previous ultraviolet observation of c Lup, obtained with the International Ultraviolet Explorer (IUE) satellite. The well-exposed IUE spectrum has a S/N of approximately 15. The GHRS spectrum has 7 to 8 times higher resolution than the IUE spectrum, and a S/N approximately 6 times greater. In principle the S/N of the IUE observation could be improved up to a value of about 40 by co-addition of multiple observations, but its resolution could not be improved beyond what is shown here. Lines of several species are labelled in the GHRS spectrum, but are barely detectable in the IUE spectrum. The second illustration shows a 1.2  section of the GHRS spectrum of c Lup. The strong line of Pt II near 1939.8  is in accord with the known excess abundance of platinum in this star. Of special interest, however, is the presence of two lines of UV multiplet 5 of Ru II, believed to be the first identification of ionized ruthenium in a stellar spectrum. The Ru II line strengths indicate an overabundance by a factor of about 85 relative to the Sun. -D. S. Leckrone FGS ASTROMETRY: FIRST RESULTS The Early Release Observations (ERO) program has given the STScI Fine Guidance Sensors (FGS) instrument team the first real opportunity to gather data usable for assessing the scientific potential of the FGS, given the telescope's spherical aberration. The astrometric precisions reported below are worst-case estimates, since Science Verification (SV) and Cycle 1 calibrations will substantially improve our ability to retrieve scientific information from the FGS. The FGS ERO observations consisted of a set of five consecutive TRANS-mode scans of the binary ADS 11300 [= WDS 18230+1458 (2000)], obtained while HST was held in Fine Lock (i.e., jitter less than 10 mas). The length of the scans was approximately 1".2 with an average sampling step of 0.6 mas. One of the y-axis scans is shown in the first figure (dotted curve). Our low-order, piece-wise- smooth polynomial least-squares fit to the data is also shown in the figure (solid curve). One of the advantages of this particular analytical representation of the data is that the subsequent correlation analysis is performed analytically. The raw data consist of a time series of photomultiplier counts and star-selector encoder readings. These data must be transformed into the proper units and corrected for instrumental and other effects before the curve shown in the figure is obtained. The reductions were performed in two steps. We first generated a coarse grid of models with an 0.2 mag step size in magnitude difference and a 10 mas step size in projected separation (on each axis). The best-fit model in this grid provided us with the starting values around which we generated a second, finer grid of double-star models. Then a 0.05 mag step in magnitude difference and a 1 mas separation step were used. Our final results are a separation of 52 mas along the x-axis and -44 mas in y. Given the geometry of the scans, these projected separations imply a 68 mas separation on the sky. The estimates of the magnitude difference were 0.45 and 0.3 mag along the two axes. The comparison between the observed and best-fit model is shown in the second figure (again for the y axis). A definitive error analysis is difficult in the present situation but reasonable estimates can be made. By comparing the results obtained using the five different scans, we estimate an internal error of 1 mas for the separation. The external precision is impossible to evaluate at present because of the lack of comparison values from planned SV observations. However, some idea of this can be obtained by intercomparing the results obtained with two very different sets of models. It appears from this type of double-check that at least 5 mas can be reached for the angular separation. The separation of the binary, as predicted using the old (1975) orbital parameter set, is about 50 mas but the error bars are large. The WDS catalog lists a visual magnitude difference of 0.6 for ADS 11300. Considering pass- band differences and the as yet unknown FGS photometric errors, it is consistent with the value of 0.4 mag derived above (mean of the x and y axes). A magnitude difference precision of 0.15 mag is conservative. -M. G. Lattanzi, B. Bucciarelli, & L. G. Taff HST Joint Discussion at IAU General Assembly Astronomers attending the General Assembly of the International Astronomical Union in Buenos Aires are invited to attend an all-day Joint Discussion on HST results, to be held on July 31. The Scientific Organizing Committee for this Joint Discussion is co-chaired by D. Macchetto and C. Norman, and its members are H. E. Bond, A. Boyarchuk, A. Davidsen, and G. Miley. 1992 EUROPEAN HST WORKSHOP The ST-ECF and the STScI are planning a workshop to be held in June1992 in Europe to discuss the scientific investigations possible with HST in its early years, with a concentration on optimal observing and data-analysis strategies. We hope to present results from the first year of the General Observer program, prior to the proposal deadline for Cycle 3. Details will be announced in the next Newsletter. -Ethan J. Schreier and Piero Benvenuti List of HST Observations Grows The last two issues of the Newsletter have contained detailed lists of HST observations that have been completed or are scheduled to be made in the near future. These lists have now grown too large (over 240 items each) for publication in the Newsletter. Anyone interested in the telescope's activities can obtain the information from the Space Telescope Electronic Information Service (STEIS) by downloading files from the Observer subdirectories Completed_Observations and Long_Range_Plan. (For instructions on using STEIS, see the December 1990 Newsletter.) If you do not have access to STEIS and would like copies of these reports, contact the User Support Branch. -Peter Reppert Scientific INSTRUMENTS Wide-Field and Planetary Camera During the HST safing event on May 2, the WF/PC CCDs were at a temperature of -35 C for about 80 hours, necessitating a decontamination before observations could be resumed. The first attempt at decontamination was unsuccessful, but a later attempt, during which the CCDs were warmed above 10 C for about two hours, resulted in the removal of all major contaminants. The UV flood was conserved sufficiently that no quantum-efficiency hysteresis was observed in a short test immediately after this episode. New flat fields may be required at some wavelengths for some CCDs, however, including PC8 in the blue and visible. Observations were successfully executed for several programs of the WF/PC GTOs over the past few months, including imaging of interacting galaxies, gravitational lenses, and Jupiter. Some of the early results were presented at the STScI May Workshop, as described above, and one of the Jupiter images is shown in this issue. The WF/PC Cycle 1 flat-fielding plan. As announced at the November 1990 GO Workshop, STScI plans to obtain and maintain flat-field calibrations for the WF/PC (based on exposures of the Earth's surface). The accompanying table gives the priorities for the Wide Field (WFC) and Planetary Camera (PC) modes. In addition to the filter-camera combinations listed in the table, STScI will obtain flat-field exposures of the Earth with all filters used by Cycle 1 GOs. For the Priority 1, 2, and 3 flat fields, STScI plans to obtain exposures at a variety of spacecraft roll angles and will create flat-field calibration files for use in pipeline processing. The observations for other filter-camera combinations will be made available (along with STSDAS software and STScI consultants) to GOs needing flat fields for those combinations. The pipeline calibration software to reprocess the science observations is available in the current distribution of STSDAS. -Richard Griffiths & John MacKenty WF/PC II At the instigation of the WF/PC II Science Team, JPL has started a design study towards the possible inclusion of fold-mirror actuators, in order to ensure alignment between the OTA pupils within the WF/PC and the secondaries of the Cassegrain repeaters. The OTA primary is re-imaged onto each of the eight WF/PC II repeater secondaries, at which points the OTA spherical aberration is corrected by the figures of the secondaries. A pupil/secondary misalignment of 7% of the pupil diameter would lead to an rms wavefront error equivalent to the current OTA problem, and an alignment tolerance of 1% is required in order for the WF/PC II to reach the minimum design goal of 60% encircled energy within 0".1 radius. Without the fold-mirror actuation, this specification might be met in only one camera head. Although the baseline design already includes actuation of the pick- off mirror to allow for overall camera misalignment when installed into HST, the Science Team has demonstrated that active adjustment of the fold-mirrors will probably be necessary, because the repeater secondaries are located at the ends of long moment arms. Fold- mirror alignment tolerance at the level of 10", corresponding to 1 micron across the 2 cm-diameter fold-mirror, is necessary for the goals to be met. The WF/PC II CCD complement presently includes four of the original TI three-phase devices, which have been judged to be flight worthy and scientifically acceptable. Further TI devices are in the qualification stages. As a back up for the rest of the needed devices, however, JPL has contracted with CCD manufacturers for the procurement of similar 8004800-pixel devices. Such devices manufactured by Loral (formerly Ford Aerospace) have shown very promising performance: read noise levels of 2-3 electrons rms and a dynamic range of over 100,000, with stable performance and a quantum efficiency at least as high as that of the TI devices. -Richard Griffiths Goddard High Resolution Spectrograph GHRS observations have continued to progress well during its Science Verification testing. Excellent spectra have been acquired for several Cycle 0 GTO programs. With the exception of a carousel problem described in detail below, which will have a significant but temporary impact, the GHRS is performing nominally. Target acquisition has seen much improvement, especially in the initial pointing of HST for GHRS targets. All 28 stars observed recently have been placed initially within a 343 spiral (1 2".75) domain, with half being located at the first pointing (1 1"). This suggests that 343 spiral searches are adequate if good stellar coordinates are used. The automatic onboard acquisition works well in terms of centering stars in the Large Science Aperture (LSA). Placement of stars in the Small Science Aperture (SSA) is currently done with blind offsets from the LSA. Two problems have been encountered with proper centering of stars in the SSA: (1) for very bright stars (the problem was first noted for z Oph, V = 2.6) in the SSA, which does not have a shutter, scattered light interferes with routine internal zero-point-deflection calibrations (DEFCALs); and (2) the SSA PEAKUP step, which should allow fine-tuning the object centering within the final aperture to be used, failed to work properly. These problems prevent SSA acquisitions from being as robust as with the LSA. Despite this, blind offsetting to the SSA can be expected to succeed at the 80-90% level (rough one-sigma estimate) relative to perfect centering. The first quite red objects have recently been acquired by the GHRS. Earlier experience, all with very blue objects, had shown responses (relative to pre-launch expectation) for the four mirrors as follows: N1 13% N2 10% A1 22% A2 33% Fortunately the response to red stars has been much closer to nominal, implying the need for wavelength-dependent adjustments to the mirror effective areas. Details have been posted in the Space Telescope Electronic Information Service (STEIS), and were included in a recent mailing to prospective Cycle 2 proposers. An augmentation to GHRS target acquisition has been approved that will allow a return to the brightest point of spiral search. (Currently the process stops as soon as the BRIGHT and FAINT limits are satisfied.) This is particularly important for acquisition of objects with poorly known UV fluxes, such as variables, and should be available for Cycle 2. Another augmentation will allow for better centering of extended objects (to about 2" diameter) in the LSA. All of the gratings have been measured for sensitivity over their full spectral ranges. Losses relative to pre-launch expectations follow from the geometric effect of spherical aberration, with the exception of a further 20-30% loss over 1600-1900  with all gratings (this discrepancy may result from errors in the ground calibration). The explicit calibration tables were mailed to Cycle 1 GOs for support of Phase II resubmissions, and more recently to Cycle 2 proposers. It has been realized that the first-order gratings G160M and G200M have contamination above 2200  from second-order light at half the wavelength (e.g., Lyman-alpha appears at 2432 ). The G270M grating has a blocking filter, and has second-order contamination only above 3300 . Full UV spectral coverage at intermediate resolution (about 25,000) is still available without any contamination with proper grating selection. The recent determination (see the March 1991 Newsletter) that the GHRS has greater sensitivity below 1500  than does the FOS leads us to consider which of the two GHRS apertures is better for detection of weak, unresolved spectral features in low-S/N data. For equal exposure times, the LSA provides a S/N gain of a factor of two, and a resolution loss of about a factor of two, relative to the SSA. Detailed simulations (using PSFs of G140L including both OTA and spectrograph contributions) have shown little difference between the two apertures for detection of weak features. The LSA is probably marginally better for isolated lines. If one also desires information about the line profile, the simpler and sharper line-spread function of the SSA is preferred. As count rates per diode fall to less than 0.02 per second in the SSA, the background noise of 0.008 counts per second will degrade the relative S/N of SSA to LSA beyond the canonical factor of two. In this event it is more likely that the LSA will be preferred. The issue of weak-line characterization in deconvolved LSA data has also been explored. In terms of deriving equivalent widths, the deconvolved LSA data perform worse than both direct PSF fits to raw LSA data and SSA data. Therefore the deconvolution of LSA data is not a benefit for this particular type of quantitative analysis. Deconvolution of large-aperture data is useful for visualization purposes, and may be of quantitative utility for some specialized investigations. -Ronald Gilliland GHRS Observations of Interstellar Lines GHRS data were successfully obtained on April 3 and 4 for two early- type stars, g 2 Velorum and HD 93521. Successful acquisition of g 2 Vel in the Small Science Aperture (SSA) was particularly welcome, since the A1 mirror, necessarily used for this bright star (V = 1.8), has not previously been very successful for target acquisition in this aperture. For the fainter star (V = 7.0) the A2 mirror was used for acquisition with success as usual. These spectra were observed for a GTO program in collaboration with C. R. O'Dell on ultraviolet interstellar absorption lines. As shown by the GHRS team (Cardelli et al., Ap. J. Letters, in press), the GHRS permits at least partial resolution of the absorption features produced by different interstellar components, a technique developed in previous decades by Hobbs and others at optical wavelengths. The figure on page 1 shows line profiles of several interstellar species observed in g 2 Vel. The high counts per diode (at half-diode intervals, thanks to the stepping pattern used) yield a S/N ratio between 120 and 160; the presence of three interstellar components is clearly indicated. The high S/N ratio also permits a study of the fixed-pattern noise (FPN), characteristic of the GHRS detectors. To help correct for FPN, each exposure was split into three subexposures, with two successive wavelength shifts of either 4 or 8 steps of the carousel encoder; the corresponding velocity shifts are either 60 or 120 km s-1. A preliminary analysis shows that for relatively smooth spectra the scatter of photon counts can be significantly reduced by correcting for the fixed-pattern noise. Thus in the S II region the observed dispersion in each of the three normalized spectra can be reduced by roughly half when divided by the FPN spectrum, determined by combining the three subexposures; this correction should permit photometric accuracies appreciably better than one percent. Also, the data suggest that the FPN at each diode does not change much when the echelle carousel is rotated by either 4 or 8 encoder steps, giving a slight shift of the spectrum on the photocathode in a direction perpendicular to the dispersion (as well as the much larger shift in the parallel direction). However a rotation of 16 steps increases the dispersion of the count differences between two subexposures by some 15%. -E. L. Fitzpatrick & L. Spitzer Deconvolution of GHRS SSA Spectra Deconvolution techniques are being developed for removing the effects of the HST spherical aberration from GHRS spectra taken with the Large Science Aperture (LSA), as described above and in a paper that is in preparation. A different sort of deconvolution is appropriate for spectra taken with the Small Science Aperture (SSA), which are undersampled because the aperture projects to only one detector diode. Deconvolution is made possible by substepping the spectrum across the detector in 1/4-diode steps, and then combining the four spectra into an oversampled spectrum. Much to my surprise, the single test case of SSA deconvolution that has been tried to date produced rather stunning results. This approach was suggested a few years ago by Ebbets and Lindler (Bull. AAS, 19, 747, 1987), and tested on comparison-lamp observations. The discussion below is based on a different technique (but other approaches will work as well), and is applied to GHRS stellar data. In this example, we deconvolve a spectrum of the peculiar star c Lupi (see David Leckrone's article above). The star was observed at intermediate resolution (R = 30,000) with the SSA, using the first- order grating G160M with substepping of 4, and 4 FP-SPLITS, yielding a mean signal-to-noise (S/N) per quarter-step of about 80. For a "truth" comparison, c Lup was also observed with Ech-B (R = 90,000) through the SSA, but one of the FP-SPLITS was lost, resulting also in a realized S/N of about 80. The figure on the next page shows 10  sections (out of the 10.4  coverage at this Echelle setting) of the original G160M/SSA spectrum, the deconvolved G160M spectrum, and the high-resolution Echelle spectrum. Realized resolving powers may be estimated by calculating the FWHM of autocorrelation functions over the sharp-lined spectral region between 1938.5 and 1939.5 . This results in FWHMs of 3.42, 2.18, and 7.45 pixels, for formal resolving powers of 33,700 (G160M), 52,900 (deconvolved G160M), and 51,500 (Ech-B), respectively. The Echelle spectrum does show some sharper lines than the deconvolved G160M, suggesting that its calculated FWHM is biased upward by the presence of some blended lines over the autocorrelation domain. Deconvolution of the SSA data provides remarkably good results, especially when it is noted that the exposure time for the Echelle observation was a factor of 2.5 longer. Further, because the wavelength coverage is greater by a factor of 3.3 for G160M, there may be observing programs for which acquisition of first-order SSA spectra, followed by deconvolution, will be preferable to Echelle spectra. The first-order grating, G160M, can be used effectively to below 1150 , and is preferable to Ech-A on the basis of photocathode cosmetics and scattered-light characteristics. In principle the Echelle SSA spectrum could itself be deconvolved to allow GHRS resolving powers well in excess of 100,000 to be reached, although when this was done for the c Lup spectrum little sharpening resulted, suggesting that the Echelle spectrum is already starting to resolve the intrinsic stellar line profiles. The combination of reduced exposure time (to reach the same S/N) and increased wavelength coverage gives the first-order grating a factor of 8.3 advantage. For projects in which full wavelength coverage is a desired feature, but still at high (approximately 50,000) resolving power, and high (approximately 100) S/N, use of first- order spectra with factor of two wavelength redundancy (all wavelengths covered twice) might be superior to Echelle observations. -Ronald Gilliland GHRS Carousel Problem The GHRS uses a carousel assembly with absolute encoders to position dispersive elements and mirrors as needed for observations. In recent weeks the carousel has failed intermittently to respond to commands, leading to three GHRS safing events. Although the risk to health and safety of the instrument from continued operation in this mode is believed very small, the impact on telescope usage is significant. The carousel is driven currently by two independent sets of electronics and motors, corresponding to the two detectors. Failures have been a problem only for side 1 (the far-UV detector). The carousel control electronics are fully cross-strapped, so that control of the carousel may be effected from either set of electronics. However, changing over to control of the carousel from only one side involves substantial changes to flight software and ground commanding, as well as the need for verification testing and recalibration of some engineering-level relations. Efforts are now underway at Ball Aerospace (prime contractor for the GHRS), Goddard, and STScI to develop the required software changes as quickly as possible. It is estimated that full implementation will require some four to six months. From recent experience, one may infer a roughly 50% failure probability for observations using side 1. It has been decided that use of side 1 will be deferred temporarily. Only programs using side 2 will continue to be implemented. Proposals that require side 1 (e.g., use of G140L or Echelle A, which have no effective side 2 replacements) will be held for now. An effort will be made to identify Cycle 1 GO/GTO proposals that use side 1 in such a way that switching to side 2 fully would not compromise the science return (e.g., G140M use can often be replaced by G160M, and a target acquisition with mirror N1 may well be feasible with mirror A2). -Ronald Gilliland High Speed Photometer The High Speed Photometer continues to operate as expected. There are no hardware problems. The throughput for the 1".0 apertures is reduced by a factor of two below pre-launch expectation due to the primary mirror's spherical aberration. There is no evidence for decreased throughput (compared to pre-launch values) within the HSP itself. The centering repeatability in the 1".0 apertures by onboard acquisitions is about 0".02, and should not affect the quality of the photometry. Currently, it is recommended that the 0".4 apertures not be used. Tests will be completed this summer that will characterize the HSP performance in detail, especially the effects of spacecraft jitter on photometry. As results are acquired they will be summarized in the STScI Newsletter. More information can be obtained from Bob Bless (UWSAL:: bless, bless@larry.sal.wisc.edu) or Lisa E. Walter (SCIVAX::walter, lisa@stsci.edu). -Bob Bless & Lisa E. Walter FGS Science During Cycles 1 & 2 The recent completion of the Fine Guidance Sensor Early Release and Science Assessment observing programs, when integrated with some Orbital Verification data analysis, allows us to present an up-to-date assessment of Cycle 1 FGS science. The bottom line is that FGS science is largely unaffected by the primary-mirror aberration and the secondary-mirror despace/tilt/decenter. The only significant effect on the FGS will be a sensitivity loss of approximately one stellar magnitude. In addition, the increased spacecraft jitter in Fine Lock, even after removal, will contribute a 1-2 mas (rms) uncertainty in positional data. In this article we will review the evidence for these assertions, the current Cycle 1 calibration plans, and improvements that can be made for Cycle 2. Because there are two very different observing modes with the FGS, namely Transfer Function and Position, we discuss them separately. Transfer Function mode is primarily designed for multiple-star work (this includes high-resolution "imaging" of more complex astronomical scenes should the observational circumstances be favorable). The astrophysical uses to which binary-star frequency and orbits may be put are sundry. They range from classical mass determinations to calibrate the mass-luminosity relationship- especially for those astrophys- ically important double stars where HST FGS observations can make meaningful measurements at orbital phases where ground-based techniques cannot-to galactic-cluster studies, which will help to understand problems such as mass segregation, kinetic-energy equipartition, and star-formation processes. Transfer Function mode, after a deeper understanding of the influences that govern the shape of the curve per se, was advertised as being capable of measuring small angular diameters and (relatively imprecisely) color indices. The former still seems feasible, since the transfer functions for several of the FGSs have sharp components comparable to the pre-launch simulations, though at somewhat lower contrast when the full primary mirror aperture is used. Measurement of color indices, however, seems improbable, owing to the Optical Telescope Assembly (OTA) aberrations. We shall discuss this in more depth below. Finally, Transfer Function mode is ideally suited to projects such as a search for binary asteroids. The data acquired for this purpose can be used simultaneously to calibrate the minor-planet linear diameter/luminosity relationship and to yield positional information that can be used to correct differentially the orbital-element set. The FGS ERO and SAO observations were all performed in Transfer Function mode. Analysis of all the ERO and SAO data indicates that Transfer Function mode, and transfer-function analysis, can support the bulk of the pre-launch expectations, except that very close (<10 mas) or faint (D V > 3) companion stars will be difficult to detect with confidence. The main difficulty is that the current OTA is producing field-dependent aberrations in the fields of the FGS. Thus, to obtain the maximum science from Transfer Function mode observing, calibrations must be differential. For Cycle 1 only, STScI will plan transfer-function calibrations in the FGS fields of view where GO science targets were observed. Because of the small number of GO programs using the Transfer Function mode, this technique will garner the most science with the greatest efficiency in terms of HST time. Using this technique and correcting after the fact for spacecraft jitter, one can measure binary separations to about 5 mas and magnitude differences to about 0.1 mag. These accuracies will depend slightly upon the magnitude difference between the two components and their separation. A very faint secondary, also very close to its primary (i.e., less than 30 mas), will not be so well resolved. Conversely, a wide (> 50 mas) double is very easy to detect and evaluate. The principal numerical problem is the relative insensitivity of transfer-function analysis to the magnitude difference. We found this to be true in our analyses of simulated data and with real data, and are continuing to explore the reasons. We feel comfortable that transfer-function analyses can work to a magnitude difference of about 3 for secondaries brighter than 17th mag. This is not very sensitive to the integrated brightness of the binary. Improving these estimates (and possibly the performance) will require better jitter-removal algorithms and the acquisition and analysis of SV data; the FGS is still relatively uncalibrated. The recommended telemetry rate for all FGS observations is 32 kbs, and in this mode, when the guide stars are in Fine Lock, there is the potential for a nearly complete removal of the spacecraft motions about the line of sight. Thus we anticipate better performance for future observing cycles. Additional Transfer Function calibrations during Cycle 1 will explore the OTA-induced field dependence and evaluate the true potential for angular-diameter measurements. While angular-diameter observations may not be calibrated properly before Cycle 2, their importance for independent measurements of nearby stars and minor planets is clear. Position mode is primarily designed for single-star work, in particular the precise determination of positions of stars brighter than V = 17. The astrophysical uses to which high-precision positions may be put are varied, and include parallax determinations for zero- age main-sequence stars, the calibration of the Cepheid period- luminosity relation, luminosity calibrations for various stellar classes, stellar kinematics, studies of open clusters (wherein HST will allow work on much fainter objects than can be reached from the ground or from HIPPARCOS), and measurement of nebular expansion rates. Although there have been no scientific observations attempted in Position mode, there is information regarding its potential precision. The analysis of FGS calibration data obtained to improve HST pointing has revealed previously unknown color-index and magnitude effects in the ground-based reference catalog. The discovery of these small (approximately 10 mas) biases in the ground-based data makes us very optimistic regarding even higher precisions with the FGS Position mode, in the near future. We believe that our original expectation of 5 mas for a single FGS positional observation will be met, following the successful calibration of the field distortions and the absolute plate scale. For parallax work, this performance implies a 2 mas precision in the deduced annual parallax when 10 reference stars are utilized over multiple observing opportunities. This value comes from the usual propagation-of-error formulae and does not include any hidden, milliarcsecond-level systematic effects. To optimize the calibration of the Position mode, which is extremely complex and time consuming, STScI will integrate much of the Cycle 1 calibrations with the formal science calibration program of the Astrometry Science Team. The two groups intend to analyze the calibration data independently. Improved estimates of the Position-mode performance will be reported in future Newsletters. -M. G. Lattanzi & L. G. Taff PROPOSAL NEWS Revision of GTO Award due to Spherical Aberration After the full scientific impact of the HST spherical aberration was understood, NASA re-evaluated the observing-time award structure for the Guaranteed Time Observers (GTOs). In general, many of the originally proposed scientific programs of the GTOs could still be accomplished, but with a significant amount of increased exposure time. Recognizing that major increases in GTO time would directly affect access to HST by General Observers (GOs), NASA worked directly with various advisory groups to ensure that a new policy on GTO awards was developed that was as fair as possible to both GTOs and GOs. After many months of discussion with the HST Science Working Group (SWG), the Space Telescope Institute Council (STIC), the Space Telescope Advisory Committee (STAC), and the Space Telescope User's Committee (STUC), NASA issued a policy statement on GTO observing time that was acceptable to the GTOs and to the GOs as represented by the STIC and STScI. The main points of this policy are detailed below: 1. GTOs may assign their observing time to any pre- maintenance-mission Cycle and specify which programs would be deferred to the post-maintenance-mis- sion era. 2. The GTO observing program must be completed within a period defined by the end of Science Verification plus 5 years, or within 2 years after the maintenance mission (whichever is later). 3. Deferred GTO programs will not be pro- tected. A GO may propose the same sci- ence on the same target, but must fully justify why such a program should be done in the pre-maintenance-mission era. 4. The baseline GTO observing time pro- gram is 2450 on- target hours (the same amount of time as prescribed by previous policies). On-target time means the pe- riod of time from the initiation of tele- scope guidance procedures (e.g., fine lock, coarse track, etc.) to the end of a given observation (e.g., shutter closure). 5. Each GTO team may propose for addi- tional time (above their baseline), not to exceed a total of 3 calendar months for all the GTOs combined. 6. These proposals will be peer reviewed by the same Time Allocation Committee (TAC) that evaluates GO proposals for Cycle 2. The TAC will review all GTO augmentation observing-time requests and make a recommendation to the HST Program Scientist, who has the responsibililty to make the final award decisions (after consultation with the STScI Director). 7. In order to ensure fair access to HST ob- serving time by GOs, another constraint was added to the policy. The total amount of GTO observing time will not exceed 30% of the time assigned to sci- entific observations averaged over the period of GTO observations. In addition, after the WF/PC II is operating, the total GTO plus WF/PC II science team share of the observatory may not exceed 40% in any given year. Although the terms of this policy provide the possibility of awarding additional observing time to the GTOs, the amount of additional time in no way restores the ability of the GTOs to accomplish their originally proposed science programs. To accomplish that goal would require an inordinate amount of extra observing time that would severely impact access to HST by the GOs. This policy is the result of much negotiation among many scientists and it is probably the best compromise that could be reached given the situation. -Edward J. Weiler Status of Science Programs for Cycles 0 and 1 The GTOs and GOs have recently completed the revisions of their current and Cycle 1 science programs. After a painstaking and time- consuming process, the observational strategies of existing GTO and GO programs were either suitably modified, or the programs were withdrawn or deferred to a time when the HST optical aberration has been corrected. The policies that have been adopted for GTO programs are described in the preceding article, and the following article discusses the recent GO reassessment in detail. This replanning effort has yielded a reconstructed science program that is nearly finished for Cycle 0 and is about to begin in earnest for observations scheduled for Cycle 1. Cycle 1 nominally begins on July 1, 1991, and will last 12 months. For those interested, several kinds of information for specific GTO and GO science programs (e.g., abstracts, target and exposure information, tentative schedule, etc.) can be obtained directly from STEIS, as well as this and future Newsletters. -Bruce Gillespie The Cycle 1 GO Reassessment The Reassessment Time Allocation Committee (TAC) met at STScI during February 25-27 to reevaluate the initial Cycle 1 General Observer (GO) program in light of the current HST capabilities. The Director's review of the TAC's recommendations took place in early March, and the PIs were notified of the results by mid-March. Members of the TAC were selected from the original Cycle 1 TAC and subdiscipline panels. The membership of the Reassessment TAC is given in the accompanying table. The task of the Reassessment TAC was to determine the continuing scientific viability and merit of all of the GO programs that were approved in 1989 for the first cycle of HST observations. The policies related to this exercise were summarized in the December 1990 Newsletter. The reassessment was carried out in order to optimize the scientific return from HST during its initial period of impaired operation with the spherically aberrated telescope optics. Since it would have been impractical to reconstruct completely the first year's science program at this time, it was decided to use the GO allocations for Cycle 1, which were made before the optical problem was known, as the basis for a revised program. Only those observations that were allocated to Cycle 1 were reviewed; future cycles were not considered during this reassessment. It was not possible to retain all of the original GO observations that remain feasible in principle because the required increases in their spacecraft time or their deferment until the installation of second- generation instruments could easily have consumed most of the available time for the next several years and precluded any new allocations for the foreseeable future. The fundamental intent has been to favor programs with greater scientific potential relative to the current state of HST, rather than pursuing heroic efforts for marginal results from proposals designed for the ideal telescope. The final approved list of high-priority GO Cycle 1 programs is given on the next four pages, where programs are ordered by Scientific Category. Listed are the PI's surname, country, institution, and program title. We present below a box giving a few statistics related to the GO Cycle 1 reassessment. Other notes and statistics were given in the March 1991 Newsletter. -Kirk D. Borne Cycle 2 Proposal Information The deadline for HST Cycle 2 proposals was recently announced in a special mailing to individuals and institutions on our mailing list. Highlights of the announcement are as follows: 1. The deadline for receipt of all materials at STScI for Cycle 2 Phase I proposals is August 16, 1991 (5 pm EDT). This deadline applies to proposals submitted in "electronic-plus-paper" form, which is required for all proposers who have access to U.S. electronic mail. For those who have no electronic access, "paper-only" proposals are permissible but must be submitted earlier, with a deadline of July 31, 1991 (5 pm EDT). Please note that the "electronic" Phase I proposal mechanism is described in the May 1990 Phase I Proposal Instructions, and is not the same as the Phase II (RPSS) system used by successful proposers after selection. RPSS-generated proposals will not be accepted for Phase I submissions. 2. The documents issued to the community in May 1990 with the Cycle 2 Call for Proposals contain instructions, forms, and pre-launch technical information. This information should be consulted by all astronomers considering proposal submissions for Cycle 2. These documents should be available in astronomy libraries, but copies can be provided upon written request to the User Support Branch. 3. There have been significant changes in the proposal instructions since May 1990 that will make proposing easier for many astronomers, and considerably revised technical information regarding current instrument and spacecraft performance is available. The recent mailing described these changes and revisions. Where practical, we have also posted this information on STEIS. Since additional clarifications and corrections to the Cycle 2 Call for Proposals will be posted in STEIS, we encourage proposers to check STEIS regularly (especially the "Cycle_2_updates" subdirectory under the "Proposer" directory.) The date for the Cycle 2 TAC meeting has not been determined at this time, but is most likely to be in mid-November. Selection notifications to Cycle 2 proposers should be mailed within a few weeks after the TAC meetings, and successful GOs will be given instructions on submitting their Phase II programs, which will be due roughly two months later. The Cycle 2 observing program will commence on July 1, 1992. In order to maintain the yearly schedule, we plan a complete revision of our user documentation and issuance of the Cycle 3 Call for Proposals early in 1992, with a proposal deadline tentatively set for July 1992. -Bruce Gillespie Director's Discretionary Programs As pointed out in the Cycle 2 Call for Proposals, it is possible for observers to be allocated HST observing time outside of the normal TAC procedures, through the Director's Discretionary (DD) program. A request for DD time might be appropriate in cases where a truly unexpected transient phenomenon occurs, when developments since the last proposal cycle make a time-critical observation necessary, or when it is desired to use HST and its instruments in an innovative way. The HST observing schedule is determined several months in advance of the actual observations. Although it is technically feasible to interrupt the schedule and initiate observations of a new target within 48 hours, such short-notice interruptions place very severe demands on the HST planning and scheduling process. Interruptions of this sort are limited to one per month. For these reasons, 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 most cases be more appropriate to submit a proposal through the normal GO procedures (as a Target of Opportunity program) than to request DD time. As noted in the Call for Proposals, DD requests should be submitted on the standard Cycle 2 forms to the User Support Branch, using the standard "paper-plus-electronic" (or, if necessary, the "paper-only") procedures. Item 3 on the Cover Page should indicate that the request is for "DD" time. In addition, the paper portion of the submission should include a cover letter describing the need for DD time. The DD programs that have been accepted to date are listed in the accompanying table. The first three were submitted between the original Cycle 1 TAC meeting and the recent TAC reassessment, and were reviewed for scientific merit during the second TAC meeting. Five additional DD requests were not accepted. -Howard E. Bond SOFTWARE NEWS STSDAS News The next major release of the Space Telescope Science Data Analysis Software (STSDAS), Version 1.2, will be coordinated with the next release of IRAF, Version 2.10. A final date for this release has not yet been established, but our current estimate is for late summer or early fall. Sites interested in staying up to date need not wait for the next major release, however. STEIS contains patch kits for STSDAS, and users may simply retrieve and install these kits in order to have a current version of the system. The kits are located in the directory Software/Stsdas/V1.1/Bugfixes and are called patch1.tar, patch2.tar, and patch3.tar. Please review the README file for the complete installation instructions. The third patch kit includes new tasks for image restoration: a Wiener filter program and a task to run the Lucy algorithm. Note: the patch kits must be installed sequentially. - Bob Hanisch Image Restoration Workshop Proceedings The proceedings of the Workshop on HST Image Restoration held at STScI in August 1990 have been published, and over 900 copies have been distributed. Our supply has been exhausted, so if you did not get one please check your local astronomy library for a copy. The volume is entitled "The Restoration of HST Images and Spectra," and was edited by R. L. White and R. J. Allen. - Bob Hanisch Telescope Image Modelling Software The Telescope Imaging Modelling (TIM) software (see the December 1988 STScI Newsletter and the May 1990 Optical Telescope Assembly Handbook) was developed at STScI to simulate images produced by HST and its scientific instruments. New features have been added to TIM recently. In particular, a new program has been provided to write appropriate input files for WF/PC obscurations at specified field positions. The TIM User Manual has been revised to document these enhancements. Release 25 of the software, along with the applicable User Manual (version 7), is now available to the general user community. In addition to the User Manual a Beginner's Guide and TIM Cookbook have also been provided with this release. The software is available to GOs and others to use at STScI, where it is installed on SCIVAX in the directory DISK$KRYPTON:[HASAN.SYS]. User guides may be requested from the User Support Branch. Offsite users may retrieve it from the STScI Electronic Information Service (STEIS) via ftp to a local VAX computer. VMS backup tapes may be requested from the User Support Branch by those users who do not have access to SCIVAX or STEIS. The process for retrieving TIM, relevant portions of the package, XCAL (a synthetic photometry package developed by Keith Horne), and the Calibration Data Base System (CDBS), used by TIM, is the same as described in the December 1990 STScI Newsletter. The README file in the STEIS directory Software/TIM describes the software and instructions for copying it to your local VAX computer. The savesets tim25.bck, xcal25.bck, cdbs25.bck may be unpacked by running the file backup.com in the Software/Tim directory. If you have questions please contact Hashima Hasan at STScI (301-338- 4519; userid HASAN). -Hashima Hasan Data Retrieval from the HST Archives As a step along the way to making the HST archives generally available to the community over computer networks, we intend to provide access on an experimental basis to the catalog of observations which is accumulating on our interim archive machine, the Data Management Facility (DMF). The DMF catalog can be queried with the software tool STARCAT, which permits browsing of the catalog and compilation of lists of data sets that may later be retrieved upon request. Interested users should contact the User Support Branch (800-544-8125; userid USB) for information on STARCAT, and instructions for running it on our "stsci" computer using "telnet." We will also be interested in comments on STARCAT as we design the user interface software for DADS, the final HST archive system. The utility of STARCAT is unfortunately limited by the fact that many of the keywords for old data in the catalog are presently not correct. This problem will be fixed by re-processing the old data, an activity that is currently planned to start at the end of the summer. STARCAT searches that fail because of keyword errors can be run successfully with the help of additional information about completed observations, which is available on STEIS in the Observer/Completed_Observations directory. In order to request retrieval of data from DMF, one must know the root names of the HST data sets. STARCAT can provide these, as well as information about the proprietary status of the data. The subsequent steps to follow in order to request retrieval of data from DMF, as well as the telephone number of the "archive hotline" to call in case of difficulty, are described in the information available from USB. -Ron Allen AURA NEWS AURA Welcomes New Board Members The Association of Universities for Research in Astronomy (AURA) is pleased to welcome the following new institutional members on its Board of Directors: Michael A'Hearn (University of Maryland), Hollis Johnson (Indiana University), Edward Kibblewhite (University of Chicago), and Paul Schechter (MIT). In addition, Carole Jordan (Oxford University) has been elected as a new AURA Director-at-large. Our thanks is extended to departing Board members: Robert Dorfman (University of Maryland), Kent Honeycutt (Indiana University), Stuart Rice (University of Chicago), George Clark (MIT), and William Golden. -Lorraine Reams 1991 AURA Awards In 1990, AURA began its program of presenting two awards each at STScI and at NOAO to individuals who have made outstanding contributions in the area of science or service. On February 11, AURA presented its awards to the STScI recipients listed below. Each awardee received a certificate and cash award. Christopher Burrows received the AURA award for outstanding service, in recognition of his initiative and outstanding performance in the analysis of spherical aberration in the HST Optical Telescope Assembly (OTA). By comparing simulated images to the earliest WF/PC data received from HST, he was the first analyst to discover the existence and degree of spherical aberration in the HST OTA. Abhijit Saha received the AURA award for outstanding science in recognition of his observations of RR Lyrae stars in the distant galactic halo and the Local Group of galaxies. The periods and light curves of RR Lyrae variables have been used to estimate the distances and chemical composition of nearby and distant stars in our own and external galaxies. -Lorraine Reams HUBBLE FELLOWSHIP PROGRAM eleven New Hubble Fellows Appointed The selection process for the second year of the Hubble Fellowship Program has been completed. The awardees, selected from a pool of 115 highly qualified candidates from 24 countries, and their Host Institutions, are listed in the accompanying table. Their appointments will commence in the fall of 1991. The 1992 Hubble Fellowship Program Contingent on funding from NASA, up to 12 new Hubble Fellows will be selected this winter for terms beginning in the fall of 1992. A formal Announcement of Opportunity will be issued in mid-July 1991, and the application deadline will be November 15, 1991. The main objective of the program is to provide recent postdoctoral scientists of unusual promise and ability with opportunities for carrying out HST-related research. A qualifying Host Institution must be a scientific, non-profit U.S. organization where HST-related science can be carried out successfully. Applications will be accepted from candidates of all nationalities who have earned their doctorates after January 1, 1989, in Astronomy, Physics, and related disciplines. The duration of a Fellowship is a total of three years, which includes an initial period of two years and an extension of another year, which is granted after a positive mid-term review. The detailed Announcement of Opportunity, including the Application Instructions, is available upon request from the Hubble Fellowship Program Office at STScI (userid HFELLOWS). -Nino Panagia INSTITUTE NEWS PASP COMES TO STScI On May 1, the editorial offices of the Publications of the Astronomical Society of the Pacific (PASP) were relocated to STScI. For 23 years the PASP was edited by D. Harold McNamara (Brigham Young University), to whom the ASP and the astronomical community owe a vote of thanks for his dedicated service. The new Managing Editor of PASP is Howard E. Bond. He is assisted at STScI by Deputy Editor Abhijit Saha and Editorial Assistant Denise Dankert. Lloyd Robinson (Lick Observatory) continues as Associate Editor for Instrumentation and Software. The PASP continues to welcome manuscript submissions in all areas of astronomy, including papers describing instrumentation and software. Contributions reporting HST results, of course, are particularly welcome! -Howard E. Bond SABBATICAL & LONG-TERM VISITORS AT STScI In order to promote exchange of ideas and collaborations in HST- related science, STScI expects to provide limited funds to support visiting scientists who wish to spend extended periods of time (three to twelve months), typically on sabbatical leave from their home institutions or during the summer, doing research at STScI. In general, these visitors will have the status of STScI employees and have access to the facilities available to staff members. Established scientists who might be interested in such a visit during the summer of 1992 or during the academic year commencing in September 1992 should send a letter specifying the suggested period for the visit and other relevant details to the Visiting Scientist Program, c/o Tim Heckman (301-338-4442; userid HECKMAN), at STScI. It will be helpful if candidates include a recent curriculum vitae and a short description of their research plans. -Tim Heckman STScI MINI-WORKSHOPS STScI's program of specialized "mini-workshops" continues to be active. The following mini-workshops will be held at STScI in the coming months. A mini-workshop on "The Reion- ization of the Intergalactic Medium" is being organized by Piero Madau and Avery Meiksin, and will be held at STScI August 19-20, 1991. The primary goal of the meeting will be to discuss the current understanding of the state of the IGM, both its diffuse and clumped components, in an informal atmosphere. The schedule will be divided into four half-day sessions addressing both theory and observations. Specific topics include, but are not restricted to: the H and He Gunn-Peterson test; the UV metagalactic flux-constraints from the proximity effect and the ionization of metal systems; sources of photoionization-QSOs, AGNs, young galaxies; quasar absorption systems-HST observations at low z; and the hot IGM. A mini-workshop on "Active Galactic Nuclei" will be held August 21- 23, 1991, and will be devoted to AGNs at high redshifts. The primary goal of this workshop is to understand better the cosmic evolution of the AGN population by both statistical analyses of the properties of AGNs as a function of redshift and by detailed analyses of the environments of individual high-redshift AGNs. This workshop is being organized by Anuradha Koratkar. A mini-workshop on "Nonisotropic and Variable Outflows from Stars" will be held October 8-10, 1991. This workshop, organized by Laurent Drissen, Claus Leitherer, and Antonella Nota, will bring together about 50 people to discuss the properties of outflows from pre-main sequence stars, as well as OB, Be, and Wolf-Rayet stars, luminous blue variables, symbiotic stars, and supernovae. The workshop talks and posters will be published in the Astronomical Society of the Pacific Conference Series. Because of limited space, attendance at the mini-workshops is by invitation only. Interested scientists should contact any member of the organizing committees for further information. STScI SUPPORT FOR PRESS RELEASES If you believe your HST research results are newsworthy and of interest to the general public, you are encouraged to disseminate such information to the public through a press release. As a GO, it is your prerogative to release exclusively from your home institution, to co-release with STScI, or to release exclusively via STScI's Educational and Public Affairs (EPA) office. STScI offers many services to assist you in announcing new science results to the public. EPA has a positive working relationship with reporters, science journalists and TV news media around the world. In addition to printed releases with color prints, EPA can prepare video news releases in our Astronomy Visualization Laboratory utilizing computer-graphics techniques. HST scientific results are also incorporated into our quarterly educational newsletter Observer, NASA-Select TV programming, our weekly PBS TV series "Starfinder," and educational posters and slides. In the event of a major scientific discovery, STScI has the facilities in place to televise a news conference from the STScI auditorium, via NASA-Select TV. -Eric Chaisson STEIS Update The online Space Telescope Electronic Information Service (STEIS) has several new features. There is a new Long_Range_Plan subdirectory, which contains a tentative HST observing schedule for a period of at least the next six months. Observations needing real- time interactions are noted in the plan. A new weekly summary file, week_summ_date, has been added to the Observer/ Completed_Observations directory. Several other new directories have also been added: "Instrument_News," which contains updates on performance of the scientific instruments; "Policy," which contains copies of recent mailings to observers and proposers, formerly scattered throughout the directory tree; and "Proposer/Cycle_2_updates," which contains information on proposal submission. As discussed separately above, a new version of the TIM software has been posted. This includes the cdbs and xcal backup files and all of their complementary files. "Starcat" and "PASP" are new top-level directories. Starcat was created to assist Archival Researchers who use STARCAT to search the archive data base. The resulting output file containing lists of selected archive data files will appear in this directory and can then be downloaded (using anonymous ftp) to the user's home computer for use in preparing the archival data request. PASP will contain information useful to readers of the Publications of the Astronomical Society of the Pacific, whose editorial office is now located at STScI as reported above. To keep up with the latest new postings to STEIS, be sure to read the new_items file in the main directory. An electronic copy of each STScI Newsletter is available from the Stsci/Newsletters directory. -Pete Reppert and Chris O'Dea RECENT STScI PREPRINTS The following papers have appeared recently in the STScI Preprint Series. Copies may be requested from Sharon Toolan (301-338-4898; userid TOOLAN) at STScI. Please specify the preprint number when making a request. 525. "W28 and 3C 400.2: Two Shell-Like Radio X-Ray Morphologies," K S. Long, W.P. Blair, R.L. White, and Y. Matsui. 526. "Ring Nebulae around Wolf-Rayet Stars in M33," L. Drissen, M.M. Shara, and A.F.J. Moffat. 527. "Infrared Photometry of Compact Objects in the Magellanic Clouds," F.P. Israel and J. Koornneef. 528. "What Determines the Physical Quantities of Galaxies? A Two- Component Gas Model for Protogalaxies with Energy Input from Supernovae," S. Ikeuchi and C.A. Norman. 529. "The Study of Lithium in Stars like the Sun," D.R. Soderblom. 530. "The Featureless Continua and Hydrogen Lines of Seyfert 2 Galaxies," A.L. Kinney, R.R.J. Antonucci, M.J. Ward, A.S. Wilson, and M. Whittle. 531. "Relic Cosmological H II Regions and the Origin of the Lyman- alpha Forest," A. Meiksin and P. Madau. 532. "Observations of Stellar Winds from Hot Stars at 1.3 mm," C. Leitherer and C. Robert. 533. "Eclipse Studies of the Dwarf Nova HT Cas. I. Observations and System Parameters," K. Horne, J.H. Wood, and R.F. Steining. 534. "A Non-Deterministic Approach to Schmidt-Plate Astrometry," M.G. Lattanzi and B. Bucciarelli. 535. "Memberships and CM Diagrams of Young Open Clusters. I. NGC 225," M.G. Lattanzi, G. Massone, and U. Munari. 536. "In-Flight Performance of the Faint Object Camera of the Hubble Space Telescope," P. Greenfield, F. Paresce, D. Baxter, P. Hodge, R. Hook, P. Jakobsen, R. Jedrzejewski, A. Nota, W.B. Sparks, N. Towers, R. Laurance, and F. Macchetto. 537. "Cataclysmic-Variable Evolution: Clues from the Underlying White Dwarf," E.M. Sion. 538. "The Dark-Matter Content of Spiral Galaxies," P. Salucci, K.M. Ashman, and M. Persic. 539. "Radiatively and Shock-Excited H2 in Magellanic H II Regions," F.P. Israel and J. Koornneef. 540. "What are the GHz-Peaked-Spectrum Radio Sources?," C.P. O'Dea, S.A. Baum, and C. Stanghellini. 541. "Weighted Slit Extraction of Low-Dispersion IUE Spectral Data," A.L. Kinney, R Bohlin, and J.D. Neill. 542. "Studies of Dynamical Properties of Globular Clusters. VI. The High-Concentration Cluster NGC 6397," G. Meylan and M. Major. 543. "Rotation and Emission Lines in Stars and Accretion Disks," K. Horne and S.H. Saar. 544. "Interstellar Ca II in the Galactic Halo and in QSO Absorption Systems," D.V. Bowen. 545. "Massive Star Formation and Superwinds in IRAS 19254-7245 (The TSuper Antennae')," L. Colina, S. Lipari, and F. Macchetto. 546. "An Optical Study of 3C 31, 3C 66B, 3C 120, and their Jets," D. Fraix-Burnet, D. Golombek, F.D. Macchetto, and J.-L. Nieto. 547. "Echo Images of AGN Broad-Line Regions," W.F. Welsh and K. Horne. HOW TO CONTACT STScI Telephone: If an individual staff member's extension is not known, the number for general use is 301-338-4700. Telex: 6849101-STSCI Fax: 301-338-4767 Mail: STScI 3700 San Martin Drive Baltimore, MD 21218 USA E-mail: It is possible to reach most staff members at STScI on SPAN, Bitnet, and Internet. Address formats are as follows: SPAN: SCIVAX::userid or 6559::userid Bitnet: userid@stsci.bitnet Internet: userid@stsci.edu In most, but not all, cases the userid is the staff member's last name. Alternatively, many userids are published in the Membership Directory of the American Astronomical Society. If you have difficulty reaching someone, please send the mail to the User Support Branch (userid USB), which will forward it. The USB is the central point of contact for scientists who wish to conduct research with HST. ESA FELLOWSHIPS AT STScI Astronomers of European Space Agency (ESA) member countries are reminded of the possibility of coming to STScI as ESA Fellows. Prospective fellowship candidates should aim to work with a particular member or members of the ESA staff at STScI, and for this reason applications must be accompanied by a supporting letter from STScI. Details of the interests of staff members at STScI can be obtained from Dr. J. E. Pringle in the Academic Affairs Division (301-338- 4477, userid PRINGLE). Details of the fellowships and application procedures can be obtained from the Education Office, ESA, 8-10 rue Mario Nikis, 75738 Paris 15, France. Completed application forms must be submitted through the appropriate national authority and should reach ESA no later than March 31 for consideration in May, and no later than September 30 for consideration in November. Newsletter Notes Comments on the STScI Newsletter should be addressed to the Editor, Howard E. Bond (301-338-4718; userid BOND). Mailing-list corrections should be sent to Amy Connor (userid CONNOR). Persons who assisted in the preparation of this issue include John Godfrey, Dave Paradise, Pete Reppert, and Meg Urry. The STScI Newsletter is issued three to four times a year by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for the National Aeronautics and Space Administration.