* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Please note changes regarding Gyro #5 motor current problem in Section 2.3.
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *


HUBBLE SPACE TELESCOPE

   DAILY REPORT #2857

PERIOD COVERED:  0000Z (UTC) 04/23/01 - 0000Z (UTC) 04/24/01

Daily Status Report as of 114/0000Z

1.0 OBSERVATIONS SCHEDULED AND ACCOMPLISHED:

    1.1 Completed Five 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.

    1.2 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.

    1.3 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.

    1.4 Completed Seven 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.

    1.5 Completed WF/PC-2 8820 (Wavelength Stability of Narrow Band and 
Linear Ramp Filters)

        The WF/PC-2 was used to verify the mapping of wavelength as a 
function of CCD position on linear ramp filters and to check for changes in 
central wavelengths of the narrow band filters.  The proposal completed 
nominally.

    1.6 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.

    1.7 Completed STIS/CCD 8591 (The Smallest Nuclear Black Holes)

        The Space Telescope Imaging Spectrograph (CCD) was used to observe 
small nuclear black holes which are the last major unexplored part of BH 
parameter space, searching for the smallest BHs that HST can possibly 
find.  The proposal completed with no reported anomalies.

    1.8 Completed Four Sets of WF/PC-2 8816 (Cycle 9 UV Earthflats)

        The WF/PC-2 was used to obtain sequences of Earth streak flats to 
improve the quality of pipeline flat fields for the WFPC2 UV filter set and 
in order to monitor flat field stability.  There were no reported problems.

    1.9 Completed WF/PC-2 8812 (Cycle 9 Internal Monitor)

        The WF/PC-2 was used to obtain routine internal monitors for WFPC2 
in order to monitor the health of the cameras.  A variety of internal 
exposures are obtained in order to provide a monitor of the integrity of 
the CCD camera electronics in both bays {gain 7 and gain 15}, a test for 
quantum efficiency in the CCDs, and a monitor for possible buildup of 
contaminants on the CCD windows.  There were no reported problems.

    1.10 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.

    1.11 Completed WF/PC-2 8677 (Extragalactic Novae: the Maximum Magnitude 
- Rate of Decline Relation in NGC 4472)

        The WF/PC-2 was used to accomplish two goals: {1} to provide the 
first homogeneous observational constraints on theoretical models for novae 
outbursts; and {2} to assess the reliability of novae as standard candles 
by using WFPC2 to collect well sampled light curves for 20-50 novae in the 
supergiant elliptical galaxy NGC 4472, the brightest galaxy within 30 
Mpc.  Both the length of the observing window and the temporal sampling of 
the observations are specifically designed to ensure that the novae peak 
magnitudes and decline rates are measured accurately.  These data will be 
used to construct the first `Maximum Magnitude versus Rate of Decline' 
{MMRD} relation for a galaxy beyond the Local Group.  This relation is not 
only a potentially powerful standard candle, but its shape and dispersion 
are directly linked to physical parameters which govern the physics of 
novae outbursts such as the white dwarf mass, temperature and mass 
accretion rate.  The proposal completed with no reported problems.

    1.12 Completed Four Sets of WF/PC-2 8811 (Cycle 9 Standard Darks)

        The WF/PC-2 was used to obtain dark frames every week in order to 
provide data for the ongoing calibration of the CCD dark current rate, and 
to monitor and characterize the evolution of hot pixels.  Over an extended 
period these data will also provide a monitor of radiation damage to the 
CCDs.  The proposal completed with no reported problems.

    1.13 Completed WF/PC-2 8723 (A Snapshot Survey of Galactic Globular 
Clusters)

        The WF/PC-2 was used to observe the crowded centers of globular 
clusters {GCs} that heretofore have produced intriguing discoveries of new 
phenomena, most of which are not understood theoretically.  The 
observations completed with no reported problems.

    1.14 Completed WF/PC-2 8602 (A Snapshot Survey of the Sites of Recent, 
Nearby Supernovae)

        The WF/PC-2 was used to conduct a snapshot survey in V and I of the 
sites of the nearby SNe, which have precisely known positions, to obtain 
high-resolution information on their local environment.  The proposal 
completed with no reported problems.

    1.15 Completed STIS/CCD/MA1 8606 (Determining the Nature of the 
Variable Absorption in AGN: Monitoring NGC 3783 with HST And Chandra)

        The Space Telescope Imaging Spectrograph (CCD and MA1) was used to 
investigate Seyfert 1 galaxies, many of which show intrinsic UV absorption 
lines, characterized by high moderate widths, significant outflow 
velocities, and variability on time scales as small as days.  Seyferts with 
UV absorption also show variable X-ray ``warm absorbers'', characterized by 
O VII and O VIII absorption edges, which suggests a common 
origin.  Variability monitoring is the key to understanding the absorbers, 
by providing their radial locations, densities, and evolution in 
ionization, column density, velocity, and coverage of the inner active 
nucleus.  The proposal completed with no problems.

    1.16 Completed Six 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.  The observations completed with no anomalous 
activity.

    1.17 Completed STIS/CCD/MA1 8643 (Ultraviolet Properties of the Metal 
Rich M87 Globular Cluster System)

        The Space Telescope Imaging Spectrograph (CCD and MA1) was used to 
We propose to obtain far-ultraviolet photometry of the metal rich globular 
cluster system of the elliptical galaxy M87.  This system represents a key 
link between the well understood populations of the clusters and the hot 
stars in elliptical galaxies, where our physical insight is presently 
limited.  The goal is to establish the relationship between cluster metal 
abundance and the production of UV-bright populations of stars on the 
"extreme horizontal branc"' at T{eff} > 16000K.  No anomalies were reported.

    1.18 Completed STIS/MA1 8843 (Cycle 9 MAMA Dark Measurements)

        The Space Telescope Imaging Spectrograph (MA1) was used to perform 
the routine monitoring of the MAMA detector dark noise.  The proposal 
completed nominally.

    1.19 Completed STIS/MA1 8561 (The Ionizing Flux from Star-Forming Galaxies)

        The Space Telescope Imaging Spectrograph (MA1) was used to measure 
the meaningful upper limits on the amount of ionizing radiation from 
galaxies in the current epoch.  The proposal completed nominally.

    1.20 Completed STIS/CCD/MA2 8569 (A New Survey for Low-Redshift Damped 
Lyman-Alpha Lines in QSO MgII Systems)

        The Space Telescope Imaging Spectrograph (CCD and MA2) was used to 
support studies which have shown that most of the observable neutral gas 
mass in the Universe resides in QSO damped LyAlpha {DLA} systems.  However, 
at low redshift, DLA can only be found by searching in the UV with HST.  By 
boot-strapping from the MgII statistics, we will be able to further improve 
the determination of the low- redshift statistical properties of DLA {their 
incidence and cosmological mass density} and open up new opportunities for 
studies at low redshift.  The observations completed nominally.

2.0 FLIGHT OPERATIONS SUMMARY:

    2.1 Guide Star Acquisitions:
       Scheduled Acquisitions:  9
Successful:  9

  Scheduled Re-acquisitions:  7
Successful:  7

    2.2 FHST Updates:
Scheduled: 15
Successful: 15

    2.3 Operations Notes:

        HSTAR 8177 was written when the gyro #5 motor current flagged 
out-of-limits with a value of 176 mAmps at 113/152642Z and then began 
toggling between 176 mAmps and 182 aAmps.  The yellow low limit was 167 
mAmps.  Initial data extraction showed a decrease in the gyro heater duty 
cycle and a small bias shift of 25 arcsec/hour.  These changes are 
indicative of a lube patch event.  This anomalous event occurred while 
guiding.  There was no loss-of-lock or loss of science data.  More accurate 
thermal assessment will be available in two to three days.  The gyro #5 
motor current operational (yellow) limit have been modified (low=169.0 
mAmps, high=190.0 mAmps) to facilitate monitoring for any additional motor 
current changes.

        ROP DF-01A was used to dump 486 table 157 at 113/1830Z

        A TTR was written for a late acquisition of signal at 113/1917Z, 
resulting in a loss of 31 seconds of engineering data.

        The ephemeris table was uplinked at 114/0029Z per ROP DF-07A.

        Using ROP SR-1A, the SSR EDAC error counter was cleared at 114/0116Z.

3.0 SIGNIFICANT FORTHCOMING EVENTS:

        Continuation of normal science observations and calibrations.

/CAW