ACIS Instrument Support - Monthly Progress Report for June 2008

1.  ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Presented paper at SPIE meeting on the results of the
irradiation/annealing tests done at GSFC in 2005.

  ...  Executed new SI modes which allow more grades to be 
telmetered.  These SI modes are being used to compare TE and CC 
mode grade rejection to help calibrate CC mode.  Four ObsIDs 
(57774, 57766, 57748, 57739) in June.

1.3 Monitor scientific on-orbit performance of ACIS

  ...  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)

  ...  Presented paper comparing performance evolution in Suzaku 
and ACIS CCDs at SPIE meeting.

  ...  Examined CC mode data to investigate grade ratio oddities.
Confirmed that serial CTI is not the culprit.


2.  Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance. 
A review of the engineering data reveals all is well with ACIS.

2.2 Flight software maintenance

  ...  Discovered a bug in the ACIS BEP flight software.  The 
BEP's bad pixel and column lists are not being applied correctly 
to timed-exposure sub-array runs in which the readout starts after
the first image row (subarrayStartRow > 0).  A patch has been 
developed and is being tested.  Since there are very few pixels 
and columns in the flight lists, and since the bias computation 
does a relatively good job of finding bad pixels without their 
help, the impact of this bug has been slight--a few pixels have 
been flagged as bad when they weren't.

2.3 Instrument science performance

  ...  Continued close monitoring of ACIS focal plane 
temperatures.

  ...  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

  ...  Participated in CXC Cal/Ops modeling discussion group.  
Reported on improvement in focal plane temperature control since 
turning off the Detector Housing heaters.

  ...  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:

Presentations at SPIE Astronomical Instrumentation conference:
 * Grant et al., "Physics of reverse annealing in high-resistivity
   Chandra ACIS CCDs"
 * LaMarr et al. "Front- and back-illuminated X-ray CCD 
   performance in low- and high-Earth orbit: Performance trends of
   Suzaku XIS and Chandra ACIS detectors"


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