ACIS Instrument Support - Monthly Progress Report for April 2020

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).

  ...  Making plans for creating additional ECS diagnostic SI modes that use fewer CCDs and could be desirable thermally.

  ...  Presented ACIS status at April Chandra Quarterly review.

  ...  Ordered new laptop and associated equipment to replace failing laptop used to support ACIS operations and instrument monitoring.

2.  Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.  Reviewed trends in engineering data for the past 60 days; no unexpected trends were seen.

  ...  The EEPROM checksum was verified in the APR0620A load.   Will continue to run monthly.  MIT telemetry processing will automatically check the results and send out an alert if the checksum is unexpected.

  ...  The ACIS Engineering Unit remains powered off, which is the safest long-term unsupervised state.  This imposes a moratorium on new SI modes for observers, testing new FSW patches, and testing anomaly scenarios until campus access is restored.   

2.2 Flight software maintenance

  ...  ACIS flight software patch G-H-I (improved buscrash and new deahktrip) uploaded on January 24, 2020.  First new patch set since June 2014.  No issues to date.

  ...  We continue to monitor threshold crossing rates.  The current TXINGS parameters were last updated on July 28, 2016.  Threshold crossing rates may have flattened out and started decreasing recently, potentially indicating the end of solar minimum.

  ...  Released new version of the ACIS Science Instrument Software User's Guide.  This is a major update to the previous version, released in 1997, incorporating 20 years of on-orbit experience using the software..

  ...  Updating documentation of ACIS data flow through various on-board telemetry buffers.

  ...  On-going work on a QEMU processor emulator for ACIS, attempting to understand device/host character device configurations to support hardware/software ACIS commands into the emulator.

2.3 Instrument science performance

  ...  Participated in monthly ACIS operations meetings.  Discussed newly released flight software user's guide, Chandra response to COVID-19 and potential DSN problems, and thermal issues. 

  ...  Participated in SOT radiation working group telecon.

  ...  Discussed changing the behavior of SCS107, the SI safing command sequence, to replace the command that powers down all FEPs and video boards with a command to power up three FEPs, as is done during perigee passages, to keep the electronics from getting too cold.

  ...  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 new web page (http://acis.mit.edu/asc/evt-page.html), which provides the same information but is more automated.

3.2 Provide data analysis support

  ...  Participated in CXC Cal/Ops ACIS response discussion group.  Discussed allowing higher focal plane temperatures for some classes of observations, progress on temperature dependent RMFs, and verification of new DETGAIN files.

  ...  Participated in Mission Planning Constraints working group discussion of ways to reduce large ACIS temperature swings.  

  ...  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.  Continuing to improve remote operation of ACIS EGSE in the control room.

4.2 Generation of commands for ACIS observations

  ...  Supported discussion of contingency plans in case of extended DSN outages.  Supported planning for a "lights out load", an extended command load which would balance thermal and momentum needs if there were a planned long-lasting DSN outage.  Supported review of a test "lights out load".

  ...  Updating and improving a database of ACIS command load files.

  ...  Began working on contingency plans for how to update the ACIS ruleset and ACIS tables in the event of a FEP failure.

  ...  Presented and participated in an overview of Chandra safe mode for the Science Instruments.

  ...  Reviewed APR1320A, APR1420A, and APR1420B command loads.  Reviewed APR1320 and APR2720 (x2) LTS OR lists, APR1320, APR1420, and APR2020 preliminary schedules, and APR1320 and APR1420 final OR lists.

  ...  Assigned 1 SI mode. Dropped chips from 7 ObsIDs.

  ...  Checking on automated processes associated with SACGS.