ACIS Instrument Support - Monthly Progress Report for September 2023

1.  ACIS Characterization

1.3 Monitor scientific on-orbit performance of ACIS

  ...  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).

  ...  Study on ACIS particle background variability, comparing ACIS reject rates to similar reject counters on XMM EPIC-pn and the AMS particle experiment, is nearing completion.  Paper draft is under review.

2.  Engineering

2.1 Instrument hardware engineering performance

  ...  The side-B cold radiator RTD temperature sensor (1CRBT) apparently failed on September 28, reporting values consistent with the sensor failing open, except at the highest temperatures during perigee when it briefly returns to nominal readings.  All other ACIS telemetry at the time and since then has been nominal. There is a second side-A RTD, so the temperature of the cold radiator can still be monitored. The cold radiator temperature is not part of any of the thermal models used for mission planning and is not directly used for any state of health checks.

  ...  Continued work identifying documents in storage area necessary for future Chandra support (engineering drawings, etc.)

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

  ...  The EEPROM checksum was verified in the SEP0423A 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.

2.2 Flight software maintenance

  ...  New ACIS FSW patch load H-J-K was successfully uplinked on September 19. Reviewed CAP 1695 for FSW uplink and associated CAP 1708 for TXing parameter update. Monitoring software switched over from checking for v=58 to v=60. Collecting follow-up actions for documentation updates. This patch load includes three new standard patches and an update to an existing patch, which fix bugs and improves the ACIS response to unexpected shutdowns and BEP crashes. 

  ...  ACIS flight software patch H-J-K uploaded on September 19, 2022.  First new patch set since August 2022.  No issues to date.

  ...  New ACIS command, RBFATALBUF, was built, tested on the EU, and installed in the ODB.  This command is associated with one of the new patches, "mostfatal" which dumps diagnostic information before a watchdog reboot.  The new command will telemeter that additional diagnostic information to the ground.

  ...  Began discussion of expected upcoming TOO trigger of the very bright source Swift J1727 and what mitigations the ACIS team wants to put in place to prevent an unwanted TXings trigger, without removing radiation protection entirely.

  ...  We continue to monitor threshold crossing rates which continue to drop. New parameters will be uploaded in October. The current set of TXing parameters were uploaded on August 14, 2023.

2.3 Instrument science performance

  ...  Participated in monthly ACIS operations meeting.  Discussed the successful ACIS FSW patch uplink, TXing parameter updates, and our approach to preventing unwanted TXing triggers during bright source observations.

  ...  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

  ...  With the successful uplink of the "biasphase3" ACIS FSW patch, the moratorium on the use of alternating exposure mode has been lifted.  Observers can now request this mode.

  ...  ACIS memo listing calibration ObsIDs and observation characteristics (ACIS Memo #165) will no longer be updated.  Functionality is replaced by new 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.

  ...  Participated in CXC Cal/Ops response discussion group.  Discussed correcting for sacrificial charge in Cas A, creating new RMFs for warm temperatures, running HETG observations at temperatures up to -105C, and CTI correction at high temperatures.


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.  Improved procedures to synchronize ACIS EGSE at OCC and MKI.

4.2 Generation of commands for ACIS observations

  ...  MIT ACIS operations specialist job posted.  Collecting resumes.  Budget uncertainty necessitates a slow hiring processing.

  ...  Assigned ACIS SI modes for most of cycle 25. Notified USINT about remaining problematic configurations. Checked that chip drop configurations for ObsIDs in the LTS map to existing SI modes.

  ...  Began work on a new Next-In-Line SI mode for use during HRC observations which would telemeter TXings rates in FMT1.

  ...  Participated in discussion of proposed new OR list format and how it would interact with ACIS OR list review software. Successfully tested an example OR list with ACIS review software.

  ...  Reviewed SEP1123A, SEP1123B, and AUG2123T command loads; SEP1123 (x2), OCT0123 final OR lists; SEP1123 (x2) preliminary schedules; and SEP2523 LTS OR list.

  ...  Checking on automated processes associated with SACGS.