HUBBLE SPACE TELESCOPE

                       DAILY REPORT #2461

PERIOD COVERED:  0000Z (UTC) 09/20/99 - 0000Z (UTC) 09/21/99

Daily Status Report as of 264/0000Z

1.0 OBSERVATIONS SCHEDULED AND ACCOMPLISHED:

   1.1 Completed STIS/CCD 8172 (STIS Deep DLA Imaging Survey II)

       The Space Telescope Imaging Spectrograph (CCD) was used to make deep
observations of quasar/alpha galaxy PKS0201+11.  The HST imaging, together with
ground-based spectroscopy, will unify absorption-line studies and faint galaxy
imaging studies, providing a comprehensive picture of the history of assembly,
star formation, gas consumption, and chemical enrichment in the Damped
Lyman-Alpha galaxies.  The observations were executed as scheduled, and no
anomalies were noted.  

   1.2 Completed WF/PC-2 8436 (POMS Test Proposal: WFII Backup Parallel Archive
Proposal II)

       The WF/PC-2 was used to make archive observations parallel to the prime
science observations as part of a POMS test proposal.  This is a POMS test
proposal designed to simulate scientific plans.  The observations were
completed as planned, and no anomalies were reported. 

   1.3 Completed Two Sets of WF/PC-2 8457 (UV Earthflats)

       The WF/PC-2 was used to make a ultraviolet Earth flat calibration
image.  This is to improve the quality of pipeline the ultraviolet flatfields. 
As described in HSTAR 7261 and yesterday’s report, the
acquisition/re-acquisitions for the second iteration of this proposal failed
and the take data flag remained down.  Otherwise, the observations were
completed as scheduled, and no problems were reported.  

   1.4 Completed Two Sets of WF/PC-2 8345 (Multipolar Bubbles and Jets in Very
Low Excitation Planetary Nebulae - A WF/PC-2 H-Alpha Imaging Survey)

       The WF/PC-2 was used to make H-Alpha observations of the very low
excitation planetary nebula PK275-03D1 in order to study its multipolar bubbles
and jets.  Comparison of the morphology of this young PNe sample with more
evolved PNe populations will set new constraints on models for the production
of jet-like outflows and nebular evolution.  The observations were completed as
planned, and no problems were reported.  

   1.5 Completed Three Sets of STIS/CCD 8406 (POMS Test Proposal: STIS
Non-Scripted Parallel Proposal Continuation V)

       The Space Telescope Imaging Spectrograph (CCD) was used to make low
galactic latitude observations taken in parallel with the prime science
observations as part of a POMS proposal.  This is a STIS non-scripted parallel
Condition V proposal.  The observations were completed as scheduled, and no
anomalies were reported.  

   1.6 Completed Five Sets of WF/PC-2 8442 (WF/PC-2 Cycle 8 Standard Darks)

       The WF/PC-2 was used to make a series of Cycle 8 standard dark
calibration observations.  This dark calibration program obtains 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.  As
described in HSTAR 7261 and yesterday’s report, the acquisition/re-acquisitions
for the third iteration of this proposal failed and the take data flag remained
down.  Otherwise, the observations were executed as scheduled, and no further
anomalies were noted.  

   1.7 Completed Two Sets of STIS/CCD 8408 (STIS CCD Dark Monitor C8)

       The Space Telescope Imaging Spectrograph (CCD) was used to make a CCD
bias calibration observation.  This is to monitor the darks for the STIS CCD. 
The observations were executed as scheduled, and no anomalies were reported.  

   1.8 Completed Two Sets of WF/PC-2 8443 (WF/PC-2 Cycle-8 Supplemental Darks
pt1/3)

       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 were completed as planned, and no problems were reported.  

   1.9 Completed FGS 8309 (A Link Between Massive Binary Stars and Non-thermal
Radio Emission)

       The Fine Guidance Sensors were used to make astrometric observations of
the massive Wolf-Rayet binary star WR105 and several nearby reference stars. 
Non-thermal radio emission in Wolf-Rayet stars is explained in terms of
synchrotron emission from shocks in the stellar wind.  The observations were
executed as scheduled, and no anomalies were noted.  

   1.10 Completed Two Sets of WF/PC-2 8090 (POMS Test Proposal: WF-II Parallel
Archive Proposal Continuation)

       The WF/PC-2 was used in the parallel mode to make some low galactic
latitude archive observations.  The program will be used to take parallel
images of random areas of the sky.  The observations were executed as
scheduled, and no anomalies were noted.  

   1.11 Completed Two Sets of WF/PC-2 6603 (Probing Proto-Planetary Disks in
the Orion Nebula)

       The WF/PC-2 was used to make images of the proto-planetary disk NGC-1976
which is located in the Orion Nebula.  This is to study the fundamental
physical properties and structures of recently discovered, and uniquely
visible, proto-planetary disks around young stars.  As described in HSTAR 7261
and yesterday’s report, the acquisition/re-acquisitions for the first iteration
of this proposal failed and the take data flag remained down.  Then, during the
second iteration, the high voltage was unexpectedly turned off as described in
2.3 and HSTAR 7264.  This occurred about 45 minutes before this
eight-and-one-half-hour proposal had completed.  No further problems were
reported.  

   1.12 Completed STIS/CCD 8409 (STIS CCD Bias Monitor C8)

       The Space Telescope Imaging Spectrograph (CCD) was to be used to make a
CCD bias calibration observation.  As described in HSTAR 7261 and yesterday’s
report, the acquisition/re-acquisitions for this proposal failed and the take
data flag remained down. 

   1.13 Completed STIS/MA1 8431 (Doppler Test of Far UV MAMA with Jenkins Slit)

       The Space Telescope Imaging Spectrograph (MA1) was to be used to execute
a Doppler test to measure the limiting resolving power of the far-ultraviolet
MAMA using the Jenkins 0.100x0.030 slit.  Observations were to be made of
standard star HD141556.  About one hour into this approximate five-hour
proposal, the event described in 2.3 and HSTAR 7267 occurred, causing the
remaining observations to be lost.  Otherwise, the observations were completed
as planned, and no further anomalies were noted.  

   1.14 Completed STIS/CCD/MA1 8188 (Snapshot Spectroscopic Diagnostic Survey
of the Symbiotic Stars)

       The Space Telescope imaging Spectrograph (CCD and MA1) was used to make
ultraviolet observations of star V835-Cen as part of a snapshot spectroscopic
diagnostic survey of symbiotic stars.  Using these data we will be able to
establish meaningful statistical limits on the nature of hot component sources
of ionization and fundamental wind parameters, which are vital steps toward
understanding the accretion hydrodynamics and the evolutionary status of
symbiotic systems.  A wavelength calibration image was also taken.  The
observations were executed as scheduled, and no anomalies were noted.  

2.0 FLIGHT OPERATIONS SUMMARY:

   2.1 Guide Star Acquisitions: 

                            Scheduled Acquisitions: 6
                                        Successful: 6

                         Scheduled Re-acquisitions: 10
                                        Successful:  6

       Yesterday’s report presented HSTAR 7261, describing
acquisition/re-acquisition failures due to the search radius limit being
exceeded.  Since that report, additional re-acquisition failures at 263/1043Z,
263/1129Z, 263/1221Z, and 263/1358Z occurred from the same event.

   2.2 FHST Updates: 

                              Scheduled: 11
                             Successful: 11

   2.3 Operations Notes: 

       Using ROP SR-1, the SSR EDAC error counter was reset two times.

       At 263/154441Z, several STIS MAMA-2 status buffer messages were received
indicating that the high voltage had been turned off.  HSTAR 7264 was written. 
The proposal detailed in 1.11 was affected.

       Per HSTAR 7267, at 263/194915Z, an NSSC-1 status buffer message was
generated for a CU/SDF error, along with a host of STIS error messages. 
Analysis by SEs determined that this was caused by a command overlap in the
Command Timeline.  The proposal outlined in 1.13 was affected.

       Per ROP NS-3, the NSSC-1 status buffer was dumped and reset at
263/2229Z.  Then, using ROP NS-12, the STIS flight software error counter was
reset at 263/2232Z.  Finally, as directed by ROP NS-5, two SI C&DH errors were
reset at 263/2246Z.

       A TTR was written for a period of no GCMR capability, beginning at
264/0011Z, due to an NCC software problem.  Another TTR was written (for the
same problem and reason) for a period beginning at 264/0247Z.  Finally, a TTR
was written for another period of no GCMR capability that resulted in the
non-recoverable loss of 4k engineering data for the period 264/043100Z until
264/043400Z.

       At 264/031250Z, HSTAR 7268 tells about a STIS status buffer message was
received indicating that the MAMA-2 low voltage was not allowed to turn-on due
to an event flag that had been set by the flight software.  This was determined
to be related to the problems related to HSTAR 7264 (described above). 
STIS/CCD proposal 8238, occurring during the period of the next report, was
affected.

3.0 SIGNIFICANT FORTHCOMING EVENTS: 

       Continuation of normal science observations and calibrations.

/DMH