HUBBLE SPACE TELESCOPE

   DAILY REPORT #2854

PERIOD COVERED:  0000Z (UTC) 04/18/01 - 0000Z (UTC) 04/19/01

Daily Status Report as of 109/0000Z

1.0 OBSERVATIONS SCHEDULED AND ACCOMPLISHED:

    1.1 Completed Two Sets of STIS/CCD 8864 (CCD Dark Monitor-Part 2)

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

    1.2 Completed Three WF/PC-2 8824 (Decontaminations and Associated 
Observations Pt. 3/4)

        The WF/PC-2 was used for the monthly WFPC2 decons.  Also included 
are instrument monitors tied to decons: photometric stability check, focus 
monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, 
UV throughput check, VISFLAT sweep, and internal UV flat check.  There were 
no reported problems.

    1.3 Completed FGS/1 8731 (A High Angular Resolution Survey of the Most 
Massive Stars in the SMC)

        Fine Guidance Sensor #1 was used to conduct high angular resolution 
observations of some of the SMC's hottest and most luminous objects by 
conducting a comprehensive survey of nearly every spectral type in the 
upper portion of the HR diagram.  Binary or multiple star systems will be 
detected down to an unprecedented level, more than one order of magnitude 
better than possible with WFPC2.  The targets selected include a 
representative list of normal Main Sequence O-stars and their evolved 
descendents, namely supergiants, hypergiants, LBVs, and WRs, many of which 
have been previously observed by HST's spectrometers for purposes of 
cosmological calibrations.  The observations completed, and no problems 
were reported.

    1.4 Completed STIS/CCD/MA1 8670 (The Role of Polycyclic Aromatic 
Hydrocarbons in Ultraviolet Extinction)

        The Space Telescope Imaging Spectrograph (CCD and MA1) was used to 
search for structure in the ultraviolet interstellar extinction curve, with 
particular emphasis on a search for
absorption features produced by polycyclic aromatic hydrocarbons.  The 
existence of these molecules in the interstellar medium has been postulated 
to explain the infrared emission features seen in the 3-13 micron spectra 
of numerous sources.  However, these features have stubbornly resisted 
satisfactory identification.  There were no reported problems.

    1.5 Completed Three Sets of WF/PC-2 8827 (Cycle 9 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 proposal completed nominally.

    1.6 Completed Four Sets of WF/PC-2 9244 (POMS Test Proposal: WFII 
Parallel Archive Proposal Continuation)

        The WF/PC-2 was used to perform a generic target version of the 
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 Group.  As described in HSTAR 8173 and 2.1, the 
acquisition for the final iteration of this proposal defaulted to fine lock 
backup on one FGS only, possibly affecting ten observations.  Otherwise, 
the observations completed with no other anomalous activity.

    1.7 Completed WF/PC-2 8599 (A Census of Nuclear Star Clusters in 
Late-Type Spiral Galaxies)

        The WF/PC-2 was used to conduct an I-band snapshot survey of a 
well-defined sample of nearby, face-on spiral galaxies of type Scd or 
later.  The proposal completed nominally.

    1.8 Completed Five Sets of STIS/CCD 9248 (Probing the Large Scale 
Structure: Cosmic Shear Observations)

        The Space Telescope Imaging Spectrograph (CCD) was used to measure 
the distortion of light bundles from distant galaxies that probe the 
statistical properties of the intervening inhomogeneous {dark} matter 
distribution.  Its tidal gravitational field distorts the observable image 
shapes thereby causing a coherent ellipticity pattern {Cosmic Shear}.  The 
observations completed nominally.

    1.9 Completed Two Sets of WF/PC-2 8702 (The Most Elusive Nuclei of LMC 
Planetary Nebulae)

        The WF/PC-2 was used to carry out a SNAPSHOT survey of the faintest 
nuclei of planetary nebulae {PNe} in the LMC.  This program will be a 
crucial follow-on to a Cycle 8 SNAPSHOT of LMC Pne.  In thisa case the plan 
is to observe the faintest or most obscured nuclei to determine their 
evolutionary state to an accuracy not possible in the Galaxy.  These 
faintest central stars are predicted to be among the most massive nuclei, 
and owing to the typically advanced age of the surrounding nebulae, are the 
most sensitive discriminants for validating the post-AGB evolution 
timescales predicted by theory.  The observations completed with no 
reported problems.

    1.10 Completed STIS/CCD 8865 (Bias Monitor-Part 2)

        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 anomalous activity.

    1.11 Completed WF/PC-2 8683 (Imaging Of Brightest Cluster Galaxies: The 
High End Of The Black Hole Mass Distribution)

        The WF/PC-2 was used to make kinematic black hole detections in 
galaxies to decide whether they indicate that the mass correlates with both 
optical luminosity and radio power.  The observation completed with no 
reported problems.

    1.12 Completed WF/PC-2 8581 (A Search For Low-Mass Companions To 
Ultracool Dwarfs)

        The WF/PC-2 was used to search for very low-mass {VLM} companions 
to a complete sample of 120 late-M and L dwarfs, drawn mainly from the 
2MASS and SDSS surveys.  The primary goal is to determine the multiplicity 
of M < 0.1 M_odot dwarfs.  In particular, we aim to identify binary systems 
suitable for long-term astrometric monitoring and mass measurement, and 
systems with cool, sub-1000K companions.  The proposal completed with no 
reported problems.

    1.13 Completed STIS/CCD 8603 (Secular Changes In The Temperatures And 
Radii Of Extreme Helium Stars)

        The Space Telescope Imaging Spectrograph (CCD) was used to make 
observations of 15 extreme helium stars (EHEs_ which, together with IUE 
data, will give a 20-year baseline of ultraviolet spectrophotometry.  EHEs 
are luminous stellar remnants evolving rapidly to become white 
dwarfs.  They represent an important stage in the evolution of at least 
some low-mass stars, and are closely related to the R Coronae Borealis 
variables.  Models do not agree about their origin, nor about what fraction 
of normal stars pass through this phase, in which the stars have been 
completely stripped of their outer layers.  The models do predict that EHEs 
are contracting and provide rate predictions and evolutionary 
lifetimes.  The observations completed with no reported problems.

    1.14 Completed STIS/CCD 8607 (Completing the Local AGN Inventory: The 
AGN Content of Composite Nuclei)

        The Space Telescope Imaging Spectrograph (CCD) was used to increase 
the knowledge of the local space density of AGNs which is of fundamental 
importance to a number of astrophysical problems.  A significant fraction 
of nearby galaxies have nuclei whose spectra are intermediate between those 
of LINERs and nuclear starbursts.  These ``transition objects'' may be 
composite systems that contain both a central AGN and circumnuclear star 
formation.  We will test this hypothesis by obtaining spatially-resolved 
optical spectra of a well-defined sample of 15 nearby transition nuclei 
selected from the extensive ground-based survey of Ho, Filippenko, and 
Sargent.  The observations completed with no reported problems.

    1.15 Completed WF/PC-2 8719 (A Continuation Of A Snapshot Survey Of X- 
Ray Selected Central Cluster Galaxies)

        The WF/PC-2 was used to perform snapshot images of a representative 
subset of the central cluster galaxies from an X-ray selected cluster 
sample that would provide important constraints on the formation and 
evolution of dust in cluster cores that cannot be obtained from 
ground-based observations.  The observations completed as planned.

    1.16 Completed Two Sets of STIS/CCD/MA2 8621 (The Galactic Abundance 
Gradients of Boron and Iron)

        The Space Telescope Imaging Spectrograph (CCD and MA2) was used to 
provide the first measurement of the Galactic abundance gradients for Boron 
and Iron.  Boron abundances were obtained for 5 B-type stars {with 
Galactocentric distances between 4-15 kpc} from the BIII 2066 Angstrom 
line.  Optical spectroscopy of these {and other B-type} stars has yielded 
abundance gradients of -0.07 dex/kpc for N & the Alpha-elements {O, Mg, 
Si}.  Determination of Boron abundances require UV spectra.  As described 
in HSTAR 8173 and 2.1, the acquisition for the second iteration of this 
proposal defaulted to fine lock backup on one FGS only, possibly affecting 
four observations.  Otherwise, the proposal completed nominally.

    1.17 Completed STIS/MA2 8843 (Cycle 9 MAMA Dark Measurements)

        The Space Telescope Imaging Spectrograph (MA2) was used to perform 
the routine monitoring of the MAMA detector dark noise.  The proposal 
completed nominally.

2.0 FLIGHT OPERATIONS SUMMARY:

    2.1 Guide Star Acquisitions:
       Scheduled Acquisitions: 11
Successful: 11

        HSTAR 8173 documents the fact that the acquisition at 108/222925Z 
defaulted to fine lock backup on FGS-2 only when the scan step limit was 
exceeded on FGS-1.  The proposals detailed in 1.6 and 1.16 may have been 
affected.
  Scheduled Re-acquisitions:  6
Successful:  6

    2.2 FHST Updates:
Scheduled: 24
Successful: 24

    2.3 Operations Notes:

        The SSR EDAC error counter was cleared three times per ROP SR-1A.

        Operations transferred to CCS string "G" at 109/0130Z when the 
ISPNULL process on the Core Data Server on the "A" string was re-cycling at 
108/0123Z (HSTAR 8174).

3.0 SIGNIFICANT FORTHCOMING EVENTS:

        Continuation of normal science observations and calibrations.

/CAW