ACIS Instrument Support - Monthly Progress Report for March 2007

1.  ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Began preparation of a paper presenting the results of
the radiation damage/reverse annealing tests done at GSFC in 2005.

1.3 Monitor scientific on-orbit performance of ACIS

  ...  Continued investigation of bias artifacts believed to be
due to long-lived cosmic ray afterglows.  Found an example of
a long-lived cosmic ray afterglow in raw data (>10 minutes!).
Applied flight bias algorithm.  Resulting bias has an elevated
region, a few ADU above nominal, similar to the observed bias
artifacts.  Continued to search for and examine these artifacts.

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

  ...  Continued a more comprehensive study of the effect of 
focal plane temperature variations on the metrics used in ACIS
monitoring.  Study completed.  Monitoring data with new temperature 
filters applied will be posted in April.

  ...  Updated contamination monitoring.  Widened temperature
filter to increase the number of data points beyond 2005.  Increased
the number of events in each data bin to improve statistics.

1.7 Produce novel data products from the MIT ACIS database

  ...  Began collecting grade geometry information from the 
subassembly calibration data in response to a request from CXC
Cal.  This information will be used in a proposed CTI correction
algorithm for graded mode data.


2.  Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.
A review of the last 60 days of engineering data shows no unexpected 
behavior.  The new protocol for shutting down unused DEA and FEP boards 
during observations not requiring all 6 CCDs has been successful in 
reducing both peak and average operating temperatures.

2.2 Flight software maintenance

2.3 Instrument science performance

  ...  Participated in monthly ACIS operations meeting.  Discussed
focal plane temperature regulation issues, bias artifacts and issues
with bus errors/crashes when SCS 107 is run during bias calculation.

  ...  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 user question on contamination deposition rate

3.2 Provide data analysis support

  ...  Participated in CXC Cal/Ops modeling discussion group.
Discussed, among other things, graded mode calibration and improved 
contamination monitoring.

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

  ...  Examined image of recent Cyg X-1 observation where the source
was positioned just off the I1 CCD on the framestore.  Concluded that
the framestore shadow was different from, but consistent with, 
flatfield data.

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.  Prepared EGSE for possible real-time 
support during ObsID 7501 - real-time support deemed 
unnecessary.

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


Outreach:

None

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