ACIS Instrument Support - Monthly Progress Report for March 2018

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).

  ... Reviewed Special Activity Request (SAR) for upcoming raw data.

  ...  Installed new versions of ACIS software monitoring software (catnrt, getnrt, and pmon) onto remaining SAO monitoring machines.  Updates include new alerts for S/W Housekeeping channels including unexpected FEP Resets.

  ...  Prepared slides on ACIS status for the Chandra Quarterly in April.


2.  Engineering

2.1 Instrument hardware engineering performance

  ...  On day 2018:064, 5 March 2018, during ObsID 19362, ACIS had a reoccurrence of the DEA sequencer reset anomaly.  This anomaly has occurred three times previously, in 2004, 2009, and 2013 (see SPR 136, 143, 149 and ftp://acis.mit.edu/pub/SPR136-1.0.pdf).  It is believed to be due to an SEU in an Actel FPGA either on the BEP or on the DEA Interface Board.  The anomaly condition is cleared when the next science run starts, so no corrective action is required.  Confirmed telemetry verifiers consistent with this explanation and that the following observation executed nominally.  One ksec of science data was lost.
  
  ...  On day 2018:080, 21 March 2018, side B of the ACIS door mechanism was found to be enabled.  As this left ACIS one spurious command from an actual door motion, a telecon was called in which it was decided to send a NO-OP command to the SIM RCTU to verify the integrity of the command path, and then the side B door disable command.  This occurred during the same contact as the initial anomaly detection and all telemetry values returned to their previous states.  No science data was lost and no actual door movement occured.  The most likely cause for this anomaly was a single-event upset in the ACIS PSMC electronics, the same as the spurious power-down commands experience by the DPA and DEA in the past.  A Flight Note is in the works.  

  ...  After the door enable anomaly, some adjustments were made in the ACIS alert email and text lists.

  ...  Continue to monitor long term ACIS instrument performance.  All engineering data remains nominal.
  
  ...  The EEPROM checksum was verified in the MAR0518 load.   Will continue to run monthly.  MIT telemetry processing will automatically check the results and send out an alert if the checksum is unexpected.

2.2 Flight software maintenance

  ...  Flight software patch F-G-H (improved buscrash2) uploaded in June 2014.

  ...  We continue to monitor threshold crossing rates.  The current TXINGS parameters, which were last updated on July 28, 2016, will need to be updated in the next few months to keep the trigger thresholds well above the increasing particle background.  This update will likely be the last increase, as the rates should subsequently start dropping again.

  ...  Considering a patch to the ACIS flight software that would allow ACIS to monitor it's own FEP / BEP board temperatures and autonomously turn off FEP power if temperatures go above the red limit.  Requested by FOT, to allow them to "schedule more aggressively".  Discussing the drawbacks of an ACIS software patch versus OBC limit checking of engineering housekeeping.

2.3 Instrument science performance

  ...  Participated in monthly ACIS operations meeting.  Discussed recent anomalies, plans for the OCC move, the FOT plan for FEP power downs, and future TXINGs parameter updates.

  ...  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

  ...  Final review and edits of ACIS article for the upcoming Chandra newsletter.

  ...  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.

  ...  Answered user question on the absolute energy calibration of ACIS CCDs.

  ...  Helped user with access to ACIS calibration source data in the Chandra archive.

3.2 Provide data analysis support

  ...  Answered V&V scientist question on event rates in the exposure records.

  ...  Participated in Cool Targets Program working group.  Discussed SI mode assignment implementation.

  ... Participated in Mission Planning Constraints and Thermal Working Group meetings.

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

  ...  Participated in program planning for upcoming IACHEC meeting (April in Italy).

4.  OCC Support

4.1 Use of MIT/ACIS EGSE at OCC

  ...  Continued support and maintenance of ACIS EGSE software and hardware at the OCC.  Performed monthly check of all ACIS hardware and software in the TST room at the OCC.  Working on updating documentation.

  ...  New EGSE workstations for the relocated OCC have been configured and have primary monitoring software installed.  Testing ongoing.

4.2 Generation of commands for ACIS observations

  ...  In response to FOT request, discussing whether reducing ACIS power by turning off FEPs and video boards between observations (during slews and intermediate attitudes) would be desirable.  Working on the details of which commands and their timing with the FOT.

  ...  Tested an update to the format of preliminary schedules by SOT MP.

  ...  Updated SACGS to remove ACIS ops dependence on "expect" by replacing the functionality with a perl module under ACIS ops configuration control.  Initial issue with permissions on the new script fixed.  The new script runs slower than before.  Cause is understood and working on a fix.

  ...  Continued review and updating of SACGS documentation (SACGS = SOT ACIS Command Generation System).

  ...  Continuing familiarization with SACGS operation and under-the-hood functioning.

  ...  Reviewed MAR1918A and MAR1918B command loads. Reviewed MAR2618 preliminary schedule, MAR2618 final OR list, and APR0218 Long Term Schedule OR list.

  ...  Checking on automated processes associated with SACGS.