ACIS Instrument Support - Monthly Progress Report for January 2006

1.  ACIS Characterization

1.3 Monitor scientific on-orbit performance of ACIS

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

  ...  Continued work on memo for the operations team on the consequences
of a future, unprotected radiation belt transit by ACIS.  Steve O'Dell
kindly provided the evolution of the trapped-proton fluence for Chandra's
orbit.


2.  Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.
Although continuing to show slow increases in power supply temperatures, 
ACIS continues to operate normally.

  ...  Investigated ground experience with increased DEA temperatures.
Found that ACIS noise improves as DEA-Z temperatures increase.

2.3 Instrument science performance

  ...  Supported Ops discussion of changes to SACGS (SOT/ACIS Command
Generation Software) to utilize new and better calibrated energy-to-ADU
conversions.  Proposed new paradigm would assign an energy-to-ADU
conversion to each aimpoint (ACIS-I vs ACIS-S).

  ...  Investigated the corruption of a bias map from OBSID 59165, 
found that it was caused by bad telemetry.  Largely successful in 
correcting it, submitted an updated SSR file to the GOT.

  ...  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.

  ...  Participated in "monthly" ACIS operations meeting.  Discussed
thermal issues, ACIS cooling tests and proposed changes to SACGS (as
described above).

  ...  Began the process, in response to a request from the ACIS PI,
to develop strategies for using ACIS to detect levels of background
radiation that would pose a threat to itself, and communicating that
information to the OBC.


3.  CXC Support

3.1 Provide user support

  ...  Updated ACIS memo listing calibration ObsIDs and observation
characteristics (ACIS Memo #165).

3.2 Provide data analysis support

  ...  Working with CXC SDS to validate acis_process_events implementation
of serial CTI correction.  Pulseheight differences between MIT code and 
a_p_e are small and generally understood.

  ...  Working with CXC Cal on CTI correction calibration.  Validated
CXC-produced CTI calibration products for S3 at -120C.  Working with
CXC on S1 at -120C.  Initial results are good - tweaking parameters
to improve results.

  ...  Concluded testing S3 CTI correction algorithm on simulated data. 
ACIS BI CCD simulator does not include charge trailing which is an
important part of the CTI correction algorithm.  Long-term plans include
a complete rewrite of the CCD simulators to include a more physical model
of charge trapping.

  ...  Participated in CXC Cal/Ops modelling discussion group.
Updated group on progress with S3 CTI correction implementation.  Presented
comparisons of corrected and uncorrected S3 performance.  Long discussion
of ACIS QE around the Si-K edge.  Supported discussion of temperature
filters for calibration data.

  ...  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 OCC.  Replaced broken monitor.

  ...  Continued work on improving configuration management of the ACIS
workstations in the TST area of the Chandra OCC.  Work nearly complete.


Outreach:

all recent memos available at http://space.mit.edu/ACIS/iacis.html