ACIS Instrument Support - Monthly Progress Report for April 2009

1.  ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Continued work on irradiation/annealing tests done at GSFC
in 2005.  Finalizing analysis.

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)

  ...  Developed serial trailing monitoring for BI CCDs.  Now included
as part of monitoring web pages.

  ...  Examining the use of Al-K line to calibration contamination
instead of the much weaker L-complex.  Some issues with systematics
in fitting, probably due to changing background levels.  Changed
background model from quadratic to linear which seems to help.
Changes included on monitoring web page.

  ...  Began using new parameter block in addition to the
previous two during ECS observations.  Time will be spent roughly
equally in three modes: I0-I3+S2-S3, S0-S5 and I0-I3+S1+S3.  Addition
of new mode will better match distribution of ECS data to calibration 
needs.


2.  Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance. 
ACIS engineering continues to report nominal operations.

2.2 Flight software maintenance


2.3 Instrument science performance

  ...  Participated in radiation working group telecon discussing
the radiation environment during perigee as the Chandra orbit changes.
ACIS team approved changing radiation belt backoff time from 6 hrs
to 5 hrs from perigee.

  ...  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

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

  ...  Answered questions on the consistency of S1 and S3 with regards
to contamination calibration.

3.2 Provide data analysis support

  ...  Represented ACIS instrument team at IACHEC (International
Astronomical Consortium for High Energy Calibration) meeting.

  ...  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 malfunctioning tape drive.


Outreach:

none this month

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