ACIS Instrument Support - Monthly Progress Report for April 2004

1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

 [...  Set up new parameter blocks for alternating exposure mode with a grid
of exposure times.  This is for a test of the CTI/background correlation
that will begin running in May.

1.2 Monitor scientific on-orbit performance of ACIS

 [...] Analyzed flight data to search for changes in the low energy
shoulder of the FI CCD response function.  Flight performance appears
very stable.

 [...] Continued study of the step-function CTI change associated with
the Halloween CME.  At the current time, the FI CCD CTI has essentially
returned to the pre-CME trend.  One possible intepretation is that our
CTI/background correlation is inaccurate.  This will be tested with
the new grid of alternating exposure mode observations in May/June.
(http://space.mit.edu/~cgrant/cti/change/change.html)

  ...  Continued monitoring of ACIS CTI.  Updated CTI monitoring web
page (http://space.mit.edu/~cgrant/cti/).

  ...  Continued monitoring of ACIS gain.  All CCDs stable with a slow 
decline in gain slope (ADU/eV) except for I2 which continues to vary.
(http://space.mit.edu/~cgrant/gain/).

1.3 Update and improve CCD simulation

  ...  Continued work on improving FI and BI CCD models and CTI simulation 
code.  Analysis of charge injection data to extract charge-vs-volume 
dependence. Results will be described in a SPIE paper.

  ...  Produced a set of new BI QE curves for a range of depletion depths.  
These will be used by CXC Cal to test new QE/QEU combinations.


2. Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.
ACIS engineering data continutes to be stable.

2.2 Instrument science performance

  ...  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 ACIS telecons on the possible ACIS bakeout.

 [...  Attempting to characterize the performance change from a
bake using the CTI simulator.  Exploring the limitations of the
current CTI model.


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

 [...] Participated in CXC Cal/Ops RMF discussion group.  Continued
discussions on improvements in QE and QEU.

  ...  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.


Outreach:

Bautz, talk entitled "The Chandra X-ray Observatory" and an OCC tour for
the local chapter of the American Society of Metchanical Engineers



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