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

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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.
