ACIS Instrument Support - Monthly Progress Report for May 2007

1.  ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Continued work on a paper presenting the results of
the radiation damage/reverse annealing tests done at GSFC in 2005.

  ...  Prepared and reviewed new SI modes which allow more grades
to be telmetered.  These SI modes will be used to compare TE and
CC mode grade rejection to help calibrate CC mode.

1.3 Monitor scientific on-orbit performance of ACIS

  ...  Continued investigation of bias artifacts believed to be
due to long-lived cosmic ray afterglows.  Continued to evaluate
the stability and utility of "superbiases", bias maps created
from tens to hundreds of observation specific biases which remove 
the transient bias artifacts.  Created web page for further 
investigation/evaluation by the ACIS community.  Found correlation
between bias artifact rate and cosmic ray rate.  Provided
superbiases to CXC DS for testing.

  ...  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)

  ...  Collected new raw data frames.  Plan regular collection of
raw frames to help with diagnosing future problems and better 
understanding of cosmic ray artifacts.

  ...  Presented ACIS SI team report at the Chandra Quarterly Review.


2.  Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.
The ACIS instrument continues to function nominally.

2.2 Flight software maintenance

  ... Developing and testing a new ACIS flight software patch, 
"buscrash", to prevent the BEP from crashing when an SCS107 is 
executed while ACIS is computing bias maps.  See Software Problem 
Report 140: "ACIS BEP experienced a bus error during SCS107" 
(http://acis.mit.edu/axaf/spr/prob0140.html)

2.3 Instrument science performance

  ...  Participated in monthly ACIS operations meeting.  Discussed
new flight software patches, thermal issues and bias artifacts

  ...  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).

3.2 Provide data analysis support

  ...  Attended second annual meeting of the International
Astronomical Consortium for High Energy Calibration.  Discussed
possible issues with ACIS calibration.

  ...  Participated in CXC Cal/Ops modeling discussion group.
Discussed graded mode CTI correction, comparisons of CC and TE
mode calibration, bias artifacts and issues raised at the 
international 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.

  ...  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