ACIS Instrument Support - Monthly Progress Report for October 2003

1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

 [...  Continued taking a series of data in full-frame raw mode for
performance verification and monitoring.  Three ObsIDs this month
with data on all 10 CCDs.

1.2 Monitor scientific on-orbit performance of ACIS

  ...  Continued analysis of ExtCalSrc data to study efficiency 
decrease at low energies.  Updated analysis and presented at the
Chandra Calibration Workshop.

 [...  Began examining a new model for the ACIS contaminant suggested
by Dan Dewey which could reconcile the discrepancy between the
absorption time dependence measured by the cal source and by LETG.

  ...  Continued monitoring of ACIS CTI.  No significant changes beyond 
the long term slow increase.  Does not include any data after Oct.26
Chandra shutdown and massive solar activity.  
(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/).

 [...  Preparing presentation for Chandra quarterly review/IAR (Nov. 18-19)
on ACIS status.

1.4 Update and improve CCD simulation

  ...  Continued work on improving FI and BI CCD models and CTI simulation 
code.


2. Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.
Analysis of trend data over the last 60 days shows nothing unexpected.  
With the exception of a gradually increasing thermal environment, all 
engineering parameters are stable.

 [...  Providing engineering support for planning a possible instrument 
bakeout.  An engineering assessment of the relative risks and rewards of 
various strategies was sent to the PI at the end of the month.

2.2 Instrument science performance

  ...  Participated in ACIS operations bakeout planning meetings.

 [...] Prepared estimates of CCD performance changes from both
bakeout scenarios under considerations including CTI, FWHM and
QEU by scaling from ground and flight experience with 30C bakeout.  
Simulated effect of trailing charge changes as seen in -60C bakeout .

 [...] Wrote new memo on "Recommendations regarding ACIS bakeout"
(Mark Bautz for the MIT ACIS team).  Includes engineering risk
assessment, and estimates of effect of bakeout scenarios on
ACIS CCD performance.  Distributed to instrument PI and ACIS telecon group.

 [...] Quantified statistical uncertainties in low energy QE measurements
with the ExtCalSrc for bakeout calibration preparation.

  ...  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.


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.

 [...  Began knowledge transfer between instrument team and CXC 
on calibrating the CTI model used in CTI correction and in
response matrix generation.

  ...  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.


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