HUBBLE SPACE TELESCOPE
                               DAILY REPORT #946

PERIOD COVERED:  0800 EST
Daily Status Report as of 221/1200Z.

1.0 ACTIVITIES SCHEDULED AND ACCOMPLISHED:

   1.1 Completed Three Sets of WFC 4292 (Determination of the Masses and
       Densities of Pluto and Charon - Cycle 3) 

       The Wide Field Camera was used to make a total of six observations
       of the planet Pluto, its moon Charon, and a nearby reference
       standard star. These images will be used to determine the motion of
       Pluto about the Pluto/Charon barycenter which will make it possible
       to compute the mass ratio of the two bodies and put constraints on
       their masses and densities. All six observations were received and
       displayed. No anomalies were reported, and the images were reported
       to look normal. 

   1.2 Completed Three Sets of HSP/POL 1097 (X-Ray Binaries Part 2 - Cycle
       2 High) 

       The High Speed Photometer was used to make a series of twenty
       photometric observations of the X-Ray binary star Cygnus X-1 (aka,
       HDE226868) taken with several different filters. All of the
       observations were received and displayed in the OSS. They all were
       reported to look good. 

   1.3 Completed WFC 4848 (GTO Low Latitude Parallel Program  - Cycle 3 
       High) 

       The Wide Field Camera was used to make two high latitude medium-deep
       sky survey observations taken in parallel with the prime science
       observations. Both observations were received and displayed. They
       were reported to look okay. 

   1.4 Completed PC 4712 (WF/PC Cycle 2 Calibration: Measles Monitor) 

       The Planetary Camera was used to make three Earth Calibration Flat
       images to monitor fo a form of contamination known as measles. The
       observations used filter F517N, both with and without filter F122M.
       The OSS monitored the observation and assessed the data quality. The
       first image was reported to be saturated, and the last two were
       reported to look normal. 

   1.5 Completed FOS/BL 4976 (UV Rotational Light Curves for Pluto and 
       Charon's UV Spectrum - Split)
   
       The Faint object Spectrograph was used to make a TALED exposure
       subsequent to other spectral observations of the planet Pluto and
       its moon Charon. The TALED observation was received in real time. It
       was reported to look okay. After a corrective SIP maneuver was
       uplinked to the spacecraft, spectral observations were made of the
       planet Pluto. The observations were executed in fine lock. All of
       the observations were reported to look nominal. 

   1.6 Completed FOS/RD 4123 (FOS Spectral Flat Fields Monitor, Revised) 

       The Faint Object Spectrograph (Red Side Only) was used to make
       standard spectral flat calibration observations using standard star
       WD0501+527 to track the time dependence of the spectral response in
       the UV. Two status buffer error messages were generated during the
       first observation. These referred to the failure, and then the
       success, of a "speed check". This problems did not appear to affect
       the observations. The three spectral observations were reported to
       look normal. 

   1.7 Uplinked Updated Ephemeris Tables, Per MOSES 2871 

   1.8 Completed GHRS/2 3845 (Deciphering the UV Emission Lines in the T 
       Tauri systems)

       The High Resolution Spectrograph was used to make six ultraviolet
       spectral observations of the T-Tauri class star DF-Tauri to study
       the width and shape of its emission lines which will put constraints
       on the type of mechanism producing these lines. One wavelength
       calibrations and six spectral observations were received and
       displayed. No problems were reported. 

   1.9 Completed HSP/UV1 1091 (Ultraviolet Pulsations From X-Ray Pulsars) 

       The High Speed Photometer was used to make single color photometric
       observations of the pulsating X-Ray (T-Tauri Class) binary star
       known as 4U1145-619. This is to find out if this object give off
       ultraviolet, as well as X-Ray pulsations. The observations were
       executed as scheduled, and no problems were reported. 

   1.10 Completed FGS 5055 (A Critical Test of the Galactic Escape Velocity
       at R(SUN): Cycle 1 Obs.) 

       The Fine Guidance Sensors were used to make astrometric observations
       of the high velocity star G166-37 to determine its galactic escape
       velocity. The FGSs will be used in the POS mode to measure the
       target's trigonometric parallax and proper motion. The astrometric
       observations were monitored in the OSS, and no problems were seen. 

2.0 FLIGHT OPERATIONS SUMMARY: 

    2.1 Guide Star Acquisitions: 

                            Scheduled Acquisitions : 19
                                        Successful : 19
                          Scheduled Reacquisitions : 22
                                        Successful : 22
                                    Losses of Lock : 0

   2.2 FHST Updates: 

                              Scheduled : 39
                             Successful : 38

                            U/D 1,2 Role Delay failed all three iterations 
                            of tracker #1 at 221/0650Z. Full Maneuver which
                            followed was okay. 

   2.3 Significant HSTARs: None

   2.4 Operations Note: 

       An attempt to remove the uniform layer of contamination from the
       WF/PC CCD windows, which have been accumulating over the last year,
       was performed by executing a real time Flash Decontamination
       Procedure. The twenty step procedure was carried out in four uplink
       windows between 214/1818Z and 215/0026Z. The WF/PC CCD, Hot Junction
       and Radiator temperatures were monitored throughout (as down links
       permitted) and compared against the anticipated thermal performance
       to decide which if any pre-planned contingency paths were to be
       taken (none were) and how the command timing should be spaced within
       the allowable tolerances. 

       As noted in an earlier memo, the WF/PC M1 mirror heated was turned
       off approximately seven hours before starting this procedure to
       minimize the temperature gradient across the radiator. This, as
       expected, resulted in reducing the dispersion in the CCD
       temperatures during the decontamination period. After warming up,
       the heat pipe heaters were commanded off at the opening of the
       uplink window in which that activity was planned. It was anticipated
       that the temperature of the P7 CCD (used to track the warm-up
       performance) would be near it's target temperature of -2C at the
       opening of that window. It was seen to be somewhat warmer, at +1.3c,
       and hence the heat pipe heaters were turned off by ground command.
       Through out the one hour forty minutes of the decontamination
       period the CCD temperatures, with the exception of W1 remained at
       about 3C +/- 2 Degrees. This met the goal of this procedure.
       However, unexpectedly, W1 ran approximately 6 to 8 degrees colder
       than the other CCDs. The reason for this , at this time  is not
       clear. Nor is it known how effective the decon attempt will be for
       W1. Internal flats will be taken to assess how well the procedures
       worked. 

       At the start of the cool-down, when the TEC power was reapplied, the
       TEC voltages were below their normal operating voltage by about one
       volt( at about 18 volts). The TEC voltages vary with the radiator
       temperature. Since the M1 heater had been off for about 11 hours,
       the radiator at that time had fallen, as expected to approx. -49C. It
       is believed that the low voltage condition was due to the large
       thermal gradient across the CCD junctions. The TECs cooled down as
       expected, and within a few minutes after turn-on the TEC voltage
       increased to the nominal operational range. MOSES has opened an
       HSTAR on this low-voltage condition and SESD will assist in
       quantifying this condition. It is likely that the limit set used for
       the TEC voltages, with the M1 mirror heater off, may not be
       appropriate during TEC transitional periods. 

       At this time the CCDs have cooled and are nearly to their regulation
       temperatures. Note that the M1 mirror heater has been intentionally
       left powered off. If SIB's analysis of the internal flats shows that
       the decontamination was successful then the M1 mirror heater will be
       turned back on. If a repeat of the decontamination is needed the  M1
       mirror heater will already be powered off at the start. 

/GS/STScI 8/6/93

3.0 ACTIVITIES SCHEDULED FOR NEXT REPORTING PERIOD:

   3.1 Complete Three Sets of WFC 4713 (WF/PC Cycle 2 Calibration: WFC 
       Internal Delta Flats)

   3.2 Complete Two Sets of FGS 4283 (Mass Ratio Determination For Doubles 
       With Substellar Mass Members)

   3.3 Complete WFC 5013 (WF/PC Cycle 3 Calibration: WFC Flats Narrow. 2)

   3.4 Complete PC 4929 (WF/PC Cycle 2: Improved Dark Calibration)

   3.5 Complete GHRS/2 5069 (Empirical  Determination of the Wind 
       Velocity and Density Laws)

   3.6 Complete PC/WFC 4109 (WF/PC Cycle 2 Calibration: Rapid Internal 
       Monitor)

   3.7 Complete FGS 4983 (Orbital Motions of Close Binary Stars - Cycle 2 
       High)

   3.8 Complete PC 4714 (WF/PC Cycle 2 Calibration: WFC Internal Delta 
       Flats)

   3.9 Complete WFC 5080 (A Study of the Arcsecond Gravitational Lens 
       1422+321 - Cycle 3 High)

4.0 ANOMALY STATUS:
	
   4.1 Significant New Anomalies: None

   4.2 Significant Unresolved Anomalies: None

 
5.0 SIGNIFICANT FORTHCOMING EVENTS: Nothing at this time.

/DMH                        -END-