ROSAT Guest Observer Facility


ROSAT Status Report #3:


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Satellite Status:

The satellite suffered a loss of attitude on 6 April, and subsequently ended up in safe mode as a result of the extra safety procedures implemented since the loss of PSPC-A; observations scheduled for April 6-10 were lost. Another attitude loss, on 21 April, resulted in the loss of an additional day of data before normal operations were again restored. New software to handle the gyro-drift-rate problem has been ground-tested (on the engineering model) and will probably be uplinked to the spacecraft when the next attitude loss occurs. It is hoped that the new on-board program will make it easier to maintain normal opera- operations.


AO-2:

In response to AO-2, we received ~400 proposals (a 10% increase) with a total requested time of approximately the same as for AO- 1. Hence we are again about a factor of three oversubscribed, relative to our IUC input goal (180% of schedule time allocated to U.S. observations), and time critical observations are over- subscribed by an order of magnitude. The U.K. received about 20% more proposals than for AO-1, and Germany, >20% less, while the total time requested in each country hardly changed.

The AO-2 proposal review will be held in Seattle, following the AAS meeting.


SASS Update:

SASS Version 5 (the German processing system; see April 4 bulletin for a complete list of acronym definitions) arrived at GSFC on 8 April and was promptly installed. The system is now being prepared for a second end-to-end test which will be conducted the week of 29 April.

A team from SAO is currently working in Germany with the MPE group to resolve remaining interface problems that have so far impeded the smooth flow of HRI data through the SASS system. It is hoped that the upcoming end-to-end test will show SASS 5 to be sufficiently improved to permit the initiation of production processing of both PSPC and HRI data from AO-1.


End-to-End Test Summary

During the week of 25 March, the first end-to-end test (using SASS Version 4) exercised the entire USRSDC Standard Data Processing System pipeline in processing a sample of PSPC data from last summer's verification observations. Evaluated procedures included: data ingest, SASS processing (including error checking), FITS conversion, output generation, verification and validation distribution (to SAO), archiving and retrieval, and "distribution" (this activity was simulated). The total time required to process seven ROSAT days was 65 hours, although not all plotting was performed during this time. Plotting has been shown to be a bottle-neck, but corrective action (i.e., procurement of faster hardware) is underway. As expected, the end-to-end test pinpointed some problems, but overall, the procedures were found to be effective and robust.

The following table is a list of times when observations were lost due to satellite problems. This list has not yet been checked against the detailed timeline to determine which targets were lost. Observations lost will be rescheduled.

 
  Start    UT       End     UT   Reason 
 -------------   ------------- -----------------------------------
  7.2.91  7:11 -  9.2.91  5:12 SAFE MODE                                        
  9.2.91 23:07 - 10.2.91 20:58 WFC filter position mismatch                     
 22.2.91  5:50 - 22.2.91  6:41 no guide stars                                   
 22.2.91  9:08 - 22.2.91  9:13 no guide stars                                   
 22.2.91 16:28 - 22.2.91 17:16 no guide stars                                   
 22.2.91 18:57 - 22.2.91 19:00 no guide stars                                   
 22.2.91 19:54 - 22.2.91 20:06 no guide stars                                   
 23.2.91  3:19 - 23.2.91 23:46 AMCS STANDBY: NO POINTINGS                       
 25.2.91  1:23 - 25.2.91  2:02 guide star problems                              
 27.2.91  9:02 - 27.2.91 13:35 WFC filter position mismatch                     
 28.2.91 17:07 - 28.2.91 17:20 no reference stars                               
  2.3.91  5:15 -  2.3.91 13:34 WFC data lost / tape allocation                  
  2.3.91 10:17 -  2.3.91 16:54 FI  data lost / tape allocation                  
  3.3.91 23:45 -  5.3.91 18:51 AMCS STANDBY: NO POINTINGS                       
  7.3.91  5:05 -  7.3.91  3:48 inconsistent attitude solution                   
  7.3.91 16:00 -  7.3.91 16:36 inconsistent attitude solution                   
  8.3.91 14:25 -  8.3.91 14:55 inconsistent attitude solution                   
 11.3.91 19:20 - 11.3.91 19:40 inconsistent attitude solution                   
 13.3.91 02:56 - 13.3.91 ca4h  no reference stars                               
 15.3.91 11:40 - 15.3.91 12:40 inconsistent attitude solution                   
 15.3.91 13:30 - 15.3.91 14:20 inconsistent attitude solution                   
 19.3.91 19:55 - 19.3.91 20:21 bad telemetry data                               
 24.3.91 18:15 - 24.3.91 18:45 bad telemetry data                               
 25.3.91 07:04 - 25.3.91 10:22 special attitude maneuvers (gyro cal)           
 25.3.91 10:22 - 28.3.91  5:40 ca.75% lost due to solar activity (PSPC off)     
  6.4.91 08:26 -  6.4.91 08:58 P27: reference stars: NONE, ONE or TWO           
  6.4.91 09:07 -  6.4.91 18:19 reference stars: NONE (mostly)                   
  6.4.91 18:19 - 10.4.91 00:09 STANDBY, SAFE MODE, RECOVERY, FI turnon           


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Curator: Michael Arida (ADNET); arida@milkyway.gsfc.nasa.gov
HEASARC Guest Observer Facility


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This file was last modified on Tuesday, 14-Sep-1999 11:47:03 EDT

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