ACIS Instrument Support - Monthly Progress Report for January 2025


1.  ACIS Characterization

1.3 Monitor scientific on-orbit performance of ACIS

  ...  Supported the response to the LETG insert anomaly on Jan 12.  Instrument safing 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).

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 on Dec 21. The violation has not reocurred and the values are otherwise consistent with past history.  The ACIS engineering team is not concerned and thinks it's possible this was due to corrupted telemetry.

  ...  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 yellow low (caution low) limit has been changed from +68 degrees to +66.9 degrees to prevent alerts at the current values.

  ...  The EEPROM checksum was verified in the JAN1525A 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. Weekly audits were 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.

  ...  ACIS flight software patch H-K-L underwent MIT team review.  Comments and a minor code change have been incorporated, tested on the ACIS engineering unit and software simulator, and the documentation has been released.  (https://acisweb.mit.edu/pub/ACIS_Patch_H-K-L.pdf) 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.  Discussed FSW patch development, recovery from the CXC server move, focal plane temperatures during perigee passages, and changing the 1DACTAT yellow limit.

  ...  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

  ...  Provided ACIS focal plane temperature data to HETG calibration scientist, testing whether order sorting needs to use the new temperature dependent response files.

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

  ...  Finalized IACHEC 2024 meeting report and submitted to arXiv.

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.  Out-of-cycle check after COG downtime - both needed a COG recycle.  Updated the year in monitoring software.

4.2 Generation of commands for ACIS observations

  ...  Investigated blank SI mode in the OCAT for an observed ObsID.  Determined to be arcops error.

  ...  Reviewed JAN1425A, JAN1525A, and JAN2025A command loads; JAN1425, JAN2025 final OR lists; JAN2025 preliminary schedule; and JAN2725 LTS OR list.

  ...  Checking on automated processes associated with SACGS.