HUBBLE SPACE TELESCOPE

       DAILY REPORT #3076

PERIOD COVERED:  0000Z (UTC) 03/19/02 - 0000Z (UTC) 03/20/02

Daily Status Report as of 079/0000Z

1.0 OBSERVATIONS SCHEDULED AND ACCOMPLISHED:

    1.1 Completed Five Sets of ACS/WFC/HRC 8947 (Weekly Test)

        The Advanced Camera for Surveys (WFC and HRC) was used to perform 
basic tests to monitor, the read noise, the development of hot pixels and 
test for any source of noise in ACS CCD detectors.  This program will be 
executed at least once a day for the entire lifetime of ACS.  There were no 
problems reported.

    1.2 Completed Two Sets of STIS/CCD 8906 (Hot Pixel Annealing)

        The Space Telescope Imaging Spectrograph (CCD) was used to measure 
the effectiveness of the CCD hot pixel annealing process by measuring the 
dark current behavior before and after annealing and by searching for any 
window contamination effects.  In addition, CTE performance is examined by 
looking for traps in a low signal level flat.  There were no reported problems.

    1.3 Completed NCS 8967 (Start NICMOS Cooling System)

        The NICMOS Cooling System was configured to re-cool the NICMOS 
detectors, to determine the optimal science operating temperature for the 
NICMOS detectors, and to verify stable operation.  The goals are as 
follows: 1} cool the NICMOS to the coldest possible temperature as 
specified by the NICMOS team {73K} with HST at a hot attitude and the NCC 
compressor operating near its maximum allowable speed. 2} measure NICMOS 
detector performance during the cool-down and steady state operation of the 
NCS. 3} demonstrate stability {+/-0.1K} of the NICMOS detector temperature 
at the optimal science operating temperature and 4} demonstrate 
repeatability {+/-0.1 K} of NICMOS detector temperature following changes 
from the optimal science operating temperature.  All tests were successful.

2.0 FLIGHT OPERATIONS SUMMARY:

    2.1 Guide Star Acquisitions:
       Scheduled Acquisitions: 0
    Successful: 0

  Scheduled Re-acquisitions: 0
    Successful: 0

    2.2 FHST Updates:
    Scheduled: 0
    Successful: 0

    2.3 Operations Notes:

        The operations team continues to execute its responsibilities from 
the GSFC STOCC.

        At 079/0816Z, the HST coarse attitude error is 2.46 degrees.

        The NICMOS Cryo Cooler (NCC) continues operating nominally.

        SSA transmitter #1 was turned on for the interval 078/1201Z to 
078/1219Z, using ROP IC-2.

        The SSR-1 EDAC error counter was cleared at 078/1307Z per ROP SR-1A.

        As directed by an operations request, Vehicle Disturbance Test #3 
(Part 3) executed nominally between 078/171000Z and 078/234000Z.  This 
portion of VDT #3 was executed in real-time to capture NCC surging 
disturbances at the 15+ hour mark since the transition to NCC PID Operate, 
at the maximum compressor speed during surging.  This test was a 4-orbit 
test at +V3 sunpoint.  During the test interval, the fundamental NCC 
surging frequency was observed to be ~1.6 Hz, and higher harmonics of the 
surging frequency were also observed at integer multiples of the surging 
frequency, as expected.  During VDT #3 (Part 1), the fundamental surging 
frequency was observed at ~3.0 Hz (within an hour of the transition to PID 
Operate), and during the Vibration Emittance Ground Test, the fundamental 
surging frequency was observed at 3.5 Hz (within seconds of the transition 
to the maximum surging frequency).  These results are all consistent with 
nominal operation of the NCC during cooldown, as the fundamental NCC 
surging disturbance frequency drops as the system temperature drops.  As 
the NCS cools, the NCC surging frequency and its harmonics are sweeping 
through HST system modal frequencies, resulting in HST dynamic responses 
that allow identification of the various structural modes of the 
telescope.  The modal properties of HST will be used to assess attitude 
control law stability margins.

        Using ROP 09A, the telemetry format was changed at 078/2326Z.

        The following operations notes were performed during this 
operational day:
FGS HV Monitoring during the NCS activities
Coarse Attitude Determination during NCS Fill Operations
FHST 2 Mounting Bracket Limit Change and Monitoring
Continue FGS HV Monitoring until ACR3 Activation

3.0 SIGNIFICANT FORTHCOMING EVENTS:

        Continuation of Servicing Mission Orbital Verification and the 
gradual resumption of normal science observations and calibrations.

/CAW