ACIS Instrument Support - Monthly Progress Report for December 2024


1.  ACIS Characterization

1.3 Monitor scientific on-orbit performance of ACIS

  ...  On December 31, there was a ground commanded radiation shutdown due to elevated ACE rates.  The shutdown was nominal.

  ...  Continued monitoring of ACIS CTI, gain, trailing pixel pulseheight, detector efficiency, corner pixel distribution, spectral line centroid and width, and focal plane temperature. Updated monitoring web pages.  (http://space.mit.edu/~cgrant/monitor.html).

  ...  Presented a poster on ACIS status at the Twenty-five years of Chandra symposium in December.

2.  Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.  Engineering trending over the past 60 days is (mostly) nominal.

  ...  The DEA +24V housekeeping channel, 1DEP2AVO, dropped below it's yellow limit for a single frame. The violation has not reocurred and the values are otherwise consistent with past history.

  ...  The ACIS Door Potentiometer, 1DACTAT, has begun to occasionally toggle below its yellow low limit. The value has walked around over 25 years, particularly in the past few years.  It is not believed that the door itself is moving.

  ...  The EEPROM checksum was verified in the DEC0924A loads. Will continue to run monthly.  MIT telemetry processing will automatically check the results and send out an alert if the checksum is unexpected.

  ...  Continued weekly physical audit of the ACIS Engineering Unit lab.  Worked to resolve an issue with FEPs behaving during BEP side A regression testing of the FSW patch. Power-cycling resolved the issue. Weekly audits were otherwise nominal. 

2.2 Flight software maintenance

  ...  ACIS flight software patch H-J-K uploaded on September 19, 2023.  First new patch set since August 2022.

  ...  An update to the ACIS flight software to correct the TXings bug revealed by the false trigger in October has been developed and tested on the ACIS engineering unit and the ACIS software simulator.

  ...  The Engineering Change Orders for the new ACIS FSW patchload was released for internal MIT team review (ECO-1065,1066,1067).  The only change is an update to TXings which fixes the bug in exposure time calculation that caused the false trigger during the Crab pulsar observation in October (SPR 162).

  ...  We continue to monitor threshold crossing rates.  The current set of TXing parameters were uploaded on Oct 20, 2024.

2.3 Instrument science performance

  ...  Participated in monthly ACIS operations meetings.  TXings rate tracking and progress with understanding the October false trigger.

  ...  Continued daily quick-look processing of ACIS telemetry and maintained web interface to ACIS real-time data.

  ...  Continued to publish the "annotated DOT" timeline reports.


3.  CXC Support

3.1 Provide user support

  ...  ACIS memo listing calibration ObsIDs and observation characteristics (ACIS Memo #165) will no longer be updated.  Functionality is replaced by web page (http://acisweb.mit.edu/asc/evt-page.html), which provides the same information but is more automated.

3.2 Provide data analysis support

  ...  Continued to maintain ACIS calibration database of ground and flight data products.

4.  OCC Support

4.1 Use of MIT/ACIS EGSE at OCC

  ...  Continued support and maintenance of ACIS EGSE software and hardware at the Wayside OCC.  Restarted both EGSE machines routinely.

4.2 Generation of commands for ACIS observations

   ...  Working with USINT to finish cycle 26 ACIS configurations.  Provided consultation on allowable configuration for complicated bright source observation.

  ...  Continued discussions with SOT Mission Planning on implementation of fast "pickup" replan reviews, in particular dealing with dropped chips.
 
  ...  Checking on automated processes associated with SACGS.