ACIS Instrument Support - Monthly Progress Report for July 2006

1.  ACIS Characterization

1.3 Monitor scientific on-orbit performance of ACIS

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

  ...  Began monitoring of corner pixel distribution.  A Gaussian is
fit to the histogram of corner pixels values for each observation.
The centroid and width of the Gaussian are used to monitor the 
effectiveness of bias and overclock subtraction and the system
noise.  There have been no significant changes or trends in the 
corner pixel centroid or width since launch and the flight values
are consistent with those measured on the ground.
(http://space.mit.edu/~cgrant/corners)

  ...  Began a more comprehensive study of the effect of focal
plane temperature variations on the metrics used in ACIS
monitoring.  When complete, will be used to define temperature
filter criteria more appropriate to the data.

  ...  Continued work on memo for the operations team on the 
consequences of a future, unprotected radiation belt transit by ACIS.  
Awaiting final inputs, then will circulate to wider distribution.


2.  Engineering

2.1 Instrument hardware engineering performance

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

  ...  Responded to yellow *low* limit trip for FEP0 temperatures.
New versions of SI modes are turning off unused FEPs to reduce
temperatures.  Suggested lowering yellow limit.

  ...  Responded to action from MSFC telecon to review the 
pre-launch radiation study for ACIS and compare to expected 15 year 
dosages.

2.3 Instrument science performance

  ...  Participated in "monthly" ACIS operations meeting.  Reported
on corner pixel monitoring.  Discussed how to implement new 
thermal operational constraints and recent focal plane cooling test.  
In response to the reappearance of the trickle bias anomaly in May, 
discussed uploading the already existing "untricklebias" patch.  
Anomaly is still infrequent, so decided against uploading.

  ...  Reported on anomaly in JUL0306C load in which an observation
was run without a parameter block to load the instrument settings.
Much discussion on ramifications for biases and adjacent 
observations.  Anomaly was due to load review error.

  ...  Planned for future ACIS test which will collect housekeeping
data with all ten video boards powered on.  These data will be 
compared to that taken in 1999.

  ...  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 modelling discussion group.  
Discussed (among other things) focal plane temperature limits used
in V&V processing, possible issues with the implementation of tgain,
and issues with the new CTI-corrected response products for S3.

 the apparent QE "edge" feature near the 
Si-K edge and incorporating the August 2005 gain jump on I0 and I2 
into the time dependent gain correction.

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

  ...  Answered questions about CC-mode on-board grade rejects.

  ...  Answered questions about August 2005 gain anomaly on I0 and I2.

  ...  Examined new QE correction file which is intended to remove
a feature near the Si-K edge.

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