HUBBLE SPACE TELESCOPE DAILY REPORT #2235 PERIOD COVERED: 0000Z (UTC) 10/22/98 - 0000Z (UTC) 10/23/98 Daily Status Report as of 296/0000Z 1.0 ACTIVITIES SCHEDULED AND ACCOMPLISHED: 1.1 Completed Seven Sets of NIC/1/2/3 7963 (Darks: Warming Up) The Near Infrared Camera (Cameras One, Two and Three) was used to monitor the detector dark current during the interval between the end of science observations and the exhaustion of cryogen and subsequent warming of the dewar to > 100K. The observations were completed as planned, and no anomalies were noted. 1.2 Completed Three Sets of WF/PC-2 7713 (WF/P-2 Cycle 7 Supplemental Darks pt3/3) The WF/PC-2 was used to make supplemental dark calibration images. This dark calibration program obtains 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 anomalies were noted. 1.3 Completed Two Sets of STIS/CCD 7948 (CCD Dark and Bias Monitor -- Cont. to Dec. 98) The Space Telescope Imaging Spectrograph (CCD) was used to measure CCD dark current and bias rates for the two supported amplifier settings {GAIN=1 and GAIN=4} in order to gather data for making superdarks and superbiases. The data will be used to track the growth of hot pixels on the CCD in general and within the various target acquisition apertures specifically. The observations were executed as scheduled, and no anomalies were noted. 1.4 Completed WF/PC-2 7622 (WF/PC-2 Cycle 7 Internal Monitor) The WF/PC-2 was used to make a set of Cycle 7 internal monitoring calibration measurements. 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. A bias calibration and an internal flat calibration image were also taken. The observations were executed as scheduled, and no anomalies were noted. 1.5 Completed Two Sets of WF/PC-2 7431 (Snapshot Survey of Microlensed Source Stars) The WF/PC-2 was used to make snapshot survey images of microlensed source star Macho-95-3 and MACHO-104. Gravitational microlensing surveys have revealed an excess of lensing events over theoretical predictions toward both the Large Magellanic Cloud and the Galactic Bulge. The observations were completed as planned, and no anomalies were reported. 1.6 Completed NIC/1/2/3 7886 (NICMOS Snap Shot Survey of Early-Type Galaxies) The Near Infrared Camera (Cameras One, Two and Three) was used to make observations of the early-type galactic cluster Abell324 as part of a snap-shot broad-band imaging survey. Since almost all early-type galaxies harbor dust, these images which are less sensitive to extinction and will provide superior light profiles for dynamical studies of the cores of these galaxies. The observations were completed as scheduled, and no problems were reported. 1.7 Completed NIC/2 7441 (A Search for Zodiacal Dust around Bright Nearby Stars) The Near Infrared Camera (Camera Two) was used to make observations of the zodiacal lights around the bright nearby star Sirius. Dust particles around a main sequence star are quickly removed by Poynting-Robertson drag, therefore, the existence of such dust is an almost certain signature of a current presence of a population of larger bodies in orbit around the star. The observations were executed as scheduled, and no anomalies were noted. 1.8 Completed Two Sets of NIC/2 7894 (Completing A Near-Infrared Search for Very Low Mass Companions to Stars within 10 pc) The Near Infrared Camera (Camera Two) was used to make observations searching for very low mass (VLM) companions to the stars HD128620 and HU-Del. This search will be the largest, most sensitive, volume-limited search for VLM companions ever undertaken. There was a guide star acquisition failure at 295/2044Z. HSTAR 6734 was written. 1.9 Completed NIC/1/2 7226 (Search for Massive Jupiters) The Near Infrared Camera (Camera One and Two) was used to make a corographic search for massive planets around the nearby, young main sequence star RE2131+23. Because of the extreme youth of these objects, any low-mass brown dwarf and planetary companions will still be in a higher luminosity phase and thus easily detectable. A dark calibration image was also taken. The observations were executed as scheduled, and no anomalies were noted. 1.10 Completed Three Sets of STIS/CCD 8062 (POMS Test Proposal: STIS Non-Scripted Parallel Proposal Continuation) The Space Telescope Imaging Spectrograph (CCD) was used to make high galactic latitude observations taken in parallel with the prime science observations. The observations were completed as planned, and no problems were reported. 1.11 Completed STIS/CCD 7314 (Albedos and Sizes of Planetary Ring Particles) The Space Telescope Imaging Spectrograph (CCD) was used to make observations of Saturn's rings and its moon Rhea. Compositions of the rings of Saturn are poorly understood, even after spacecraft visits. Knowledge of compositions is important for understanding the origin and evolution of ring systems. We propose a series of observations of Saturn's rings to obtain high spatial-resolution spectra from 0.17 to 1.15 micron. A wavelength calibration observations was also taken. The observations were executed as scheduled, and no anomalies were noted. 1.12 Completed NIC/1/2/3 7322 (The IMF Below 1 Msun in Young Clusters: 1.9 Micron Water Band Imaging of IC348) The Near Infrared Camera (Cameras One, Two, and Three) was used to make observations of cluster IC348. This study will be the first to obtain spectral types for a young cluster population complete to K=16, and thereby quantify, to unprecedentedly high precision, the IMF below 1M{sun} in young clusters. The observations were executed as scheduled, and no anomalies were reported. 1.13 Completed WF/PC-2 7377 (Dwarf Elliptical Galaxy Snapshot Survey II) The WF/PC-2 was used to make observations of the dwarf elliptical galaxy FCC5 as part of Snapshot Survey II. This survey will provide important information on the globular cluster systems of such galaxies and the properties of their cores and nuclei. The observations were completed as planned, and no anomalies were reported. 1.14 Completed NIC/2 7244 (Imaging of the Neptune Ring) The Near Infrared Camera (Camera Two) was used to make images of the planet Neptune's rings. The arcs in the Neptune ring have not been seen since Voyager 2 imaged them in 1989. NICMOS images made within a methane band, which suppress the scattered light from Neptune, may reveal the ring arcs, the brightest components of the Neptune ring system. The observations were executed as scheduled, and no anomalies were noted. 1.15 Completed NIC/1/2/3 7227 (A Search for Low Mass/Sub-Luminous Companions to M-Stars) The Near Infrared Camera (Camera One, Two ) was used to make a search for low mass/sub-luminous companions to the low mass M class star GJ1285. Knowledge of stellar and sub-stellar masses and luminosities at and below the ~0.08 M{sun} H-burning limit is of fundamental importance. A dark calibration image was also taken. The observations were completed as planned, and no problems were reported. 1.16 Completed NIC/1/2/3 7277 (Calibration of the Cepheid P-L Relation with Observations of the Maser-Host Galaxy NGC) The Near Infrared Camera (Cameras One, Two and Three) was used to make observations of the maser-host galaxy NGC-4258 to study its Cepheid variable stars. These data will help refine the calibration of the Cepheid period-luminosity relationship. There was a guide star acquisition failure at 295/2150Z. HSTAR 6734 was written. No other problems were reported. 1.17 Completed WF/PC-2 7909 (POMS Test Proposal: WF II Parallel Archive Proposal) The WF/PC-2 was used to make parallel observations as part of the POMS test proposal. This test proposal is designed to simulate scientific plans. The observations were completed as planned, and no problems were reported. 2.0 FLIGHT OPERATIONS SUMMARY 2.1 Guide Star Acquisitions: Scheduled Acquisitions : 9 Successful : 6 Gyro #6 Failed at 295/2039Z. The motor current dropped from 219 mA (mean) to 0 mA at 295/202605Z, the Gyro Motor Current test failed safemode low limit (70mA) at 295/202605Z. The heater duty cycle increased from 18% to 32%, analog rate and gyro counts showed ringing signatures which are indicative of gyro spin down. Flexlead failure is the most probable failure mechanism. Updated #3 gyro configuration biases at 295/2248Z were followed by an ARU/PRT at 296/0038Z, a FHST map at 296/0222Z, and a ARU/PRT at 296/0222Z. There were four failed acquisitions, which occurred at 296/0239. Gyro #6 remains powered on, currently operating with gyro 3,1,5 configuration with restricted use of Safemode Recovery Load until MACRO is modified for 3 gyro configuration. There was a guide star acquisition failure at 295/2044Z. HSTAR 6734 was written. See operations item 1.8 There was a guide star acquisition failure at 295/2150Z. HSTAR 6734 was written. See operations item 1.16. Scheduled Reacquisitions : 8 Successful : 8 2.2 FHST Updates: Scheduled : 15 Successful : 15 2.3 Operations Notes: The IP line was switched to the Backup Router at 295/1925Z, followed by the switching to the Prime Router at 295/2250Z which resulted in considerably less data hits (i.e., missing minor frames). The SSR EDAC Error Counter was cleared three times (ROP SR-1). 3.0 SIGNIFICANT FORTHCOMING EVENTS: The DF-224 vehicle clock is scheduled to have its most significant bit (MSB) set to a '1' on October 26, 1998 (day 299) at approximately 204215Z. Since many ground software systems use I*4 (4 byte integer value) to represent the 32-bit vehicle clock, there was concern that the MSB would be treated as a sign bit. This could have resulted in clock times becoming negative when the 32nd bit is set. Over the past years several systems using the I*4 representation for vehicle time, have been modified. All systems, onboard and on the ground, were then checked to ensure that the rollover would cause no problems. In some cases, additional modifications were made. No problems with the rollover are anticipated. Continuation of normal science observations and calibrations. /DMH