HUBBLE SPACE TELESCOPE

       DAILY REPORT #2627

PERIOD COVERED:  0000Z (UTC) 05/18/00 - 0000Z (UTC) 05/19/00

Daily Status Report as of 140/0000Z

1.0 OBSERVATIONS SCHEDULED AND ACCOMPLISHED:

    1.1 Completed STIS/CCD/MA1/MA2 8484 (Physical Properties of H I AND H 
II Regions)

        The Space Telescope Imaging Spectrograph (CCD, MA1 and MA2) was 
used to observe Interstellar absorption lines within the wavelength 
intervals 1170-1370A and 1630-1890A in the spectra of 10 early-type 
stars.  The following objectives were achieved: {1} to measure the 
populations of the fine-structure levels of O I, C I and Si II within H I 
and H II regions, {2} to determine the ionization ratios Al I/Al III {the 
Al II line will probably be too saturated}, S I/S II/S III, and Si I/Si 
II/Si III, and {3} to measure the abundances of Mg, O, S, Ni and Si from 
unsaturated lines arising from their preferred ionization stages in H I 
regions. Objectives {1} and {2} should define local kinetic temperatures, 
densities of H atoms {both neutral and ionized}, and also the ratios of uv 
ionizing photons to electrons.  The proposal completed nominally.

    1.2 Completed Two Sets of WF/PC-2 8459 (Decontaminations and Associated 
Observations Pt. 2/2)

        The WF/PC-2 was used to perform the monthly decons.  Also included 
are instrument monitors tied to decons: photometric stability check, focus 
monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, 
and UV throughput checks.  The observations were completed nominally.

    1.3 Completed STIS/CCD 8439 (Bias Monitor-Part 2 C8)

        The Space Telescope Imaging Spectrograph (CCD) was used to monitor 
the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1, and 1x1 at 
gain = 4, to build up high-S/N superbiases and track the evolution of hot 
columns.  The proposal completed with no reported problems.

    1.4 Completed WF/PC-2 8214 (The Evolution of Globular Cluster Systems 
In Early-Type Galaxies)

        The WF/PC-2 was used to measure structural parameters {core radii 
and concentrations} of globular clusters in three early-type galaxies using 
deep, four-point dithered observations.  The observations completed nominally.

    1.5 Completed Five Sets of STIS/CCD 8808 (POMS Test Proposal: STIS 
Non-Scripted Parallel Proposal Continuation III)

        The Space Telescope Imaging Spectrograph (CCD) was used to make 
non-scripted, parallel observations as part of a POMS test proposal.  The 
observations completed with no anomalous activity.

    1.6 Completed Three Sets of WF/PC-2 8460 (Cycle 8 Supplemental Darks pt2/3)

        The WF/PC-2 was used to obtain three dark frames every day to 
provide data for monitoring and characterizing the evolution of hot 
pixels.  The observations completed with no reported problems.

    1.7 Completed Two Sets of STIS/CCD 8437 (Dark Monitor-Part 2 C8)

        The Space Telescope Imaging Spectrograph (CCD) was used to monitor 
the darks.  The proposal completed nominally.

    1.8 Completed WF/PC-2 8118 (Snapshot Survey of Galactic Globular Clusters0

        The WF/PC-2 was used to make observations of crowded centers of 
globular clusters {GCs} which have produced intriguing discoveries of new 
phenomena, most of which are not understood theoretically. This is a 
continuation of a Cycle 7 snapshot proposal, to extend such work to a much 
larger portion of the Galactic GC system.  The observations completed 
nominally, with no reported problems.

    1.9 Completed WF/PC-2 8270 (Proper Motion of the Leo II Dwarf Spheroidal)

        The WF/PC-2 was used to continue the investigation into the proper 
motion of distant satellites of the Milky Way with a series of HST 
snapshots around faint galaxies within the Leo II astrometric field.  A 
proper motion for Leo II will be determined by combining images from 111 
Palomar 200" photographic plates taken by Baade between 1950-1959 with the 
HST snapshots.  Only with the fine pixel scale of HST can we realistically 
hope to match the exquisite Baade images, which were all taken on the very 
best nights from a decade of Baade's allotment of about forty 200 arcsecond 
nights a year.  The observations completed with no reported problems.

    1.10 Completed WF/PC-2 8325 (Galaxy Evolution in Low-Density 
Environments: WFPC2 Imaging of Poor X-Ray Clusters at z=0.2-0.3)

        The WF/PC-2 was used to obtain high quality morphological 
information on galaxies within nine X-ray-selected poor clusters at 
z=0.2-0.3. These morphologies will be combined with information on the 
stellar populations of the galaxies from our on-going spectroscopic survey 
of these systems to provide a complete view of the morphological and 
spectral evolution of galaxies within these clusters.   The observations 
completed nominally.

    1.11 Completed STIS/CCD 8489 (Searching for the Hydrogen Reionization 
Edge of the Universe at 5HST)

        The Space Telescope Imaging Spectrograph (CCD) was used to observe 
36 parallel orbits {4--5 fields of 5--8 orbits each} to constrain the H 
Lyman-edge in emission that marks the transition from a neutral to a fully 
ionized IGM.  This edge is due to recombination from the H Lyman series and 
Lyman continuum, and can be used to constrain zion, one of the most 
important unknown quantities in large scale structure and cosmology.  The 
proposal completed nominally.

    1.12 Completed STIS/CCD/MA1/MA2 8257 (VV Cephei: The Egress from 
Chromospheric Eclipse)

        The Space Telescope Imaging Spectrograph (CCD, MA1 and MA2) was 
used to make choromospheric observations of the egress from eclipse of star 
VV Cephei (a.k.a., HD208816).  This is to make observations of the 
long-period {20.3 yrs} eclipsing binary VV Cephei {M2 Iab + B0} as it 
continues to emerge from chromospheric eclipse.  A wavelength calibration 
image was also taken.  The observations were executed as scheduled, and no 
anomalies were noted.

    1.13 Completed STIS/CCD/MA1 8807 (FUV Observations of EX Hya during a 
Large Multi-wavelength Campaign)

        The Space Telescope Imaging Spectrograph (CCD and MA1) was used to 
observe EX Hya, an eclipsing binary with an orbital period of 98 minutes 
and a spin period of 67 min, 2/3 of the orbital period in length. This 
object contains optically thick gas at temperatures of 10, 000 to 100, 000K 
and thin gas at 1 million Kelvins and higher temperature plasma.  As such, 
it is a source of strong emission lines throughout the FUV to IR spectral 
regions.  The proposal completed with no reported problems.

    1.14 Completed Four Sets of WF/PC-2 8805 (POMS Test Proposal: WFII 
Parallel Archive Proposal Continuation)

        The WF/PC-2 was used to perform a generic target version of the 
WFPC2 Archival Pure Parallel program.  The program will be used to take 
parallel images of random areas of the sky, following the recommendations 
of the Parallels Working.  The proposal completed with no reported problems.

2.0 FLIGHT OPERATIONS SUMMARY:

    2.1 Guide Star Acquisitions:

       Scheduled Acquisitions: 6
Successful: 6

  Scheduled Re-acquisitions: 7
Successful: 7

    2.2 FHST Updates:

Scheduled: 13
Successful: 13

    2.3 Operations Notes:



3.0 SIGNIFICANT FORTHCOMING EVENTS:

        Continuation of normal science observations and calibrations.

/CAW