ACIS Instrument Support - Monthly Progress Report for May 2004

1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

 [...  Began new test of our CTI/background relation by running
a series of alternating exposure mode observations with a grid
of exposure times.  In May there were four runs with a frametime 
of 2, 2.5, 3 and 3.5 seconds (the last with a warm focal plane 
temperature), alternating with a standard frametime of 3.2s.
Additional runs in June should complete the set.

 [...] New ACIS memo, "Reproducibility of soft-proton damage in
laboratory irradiation of ACIS CCDs" summarizes the ground
irradiation test results.  See ACIS Memo #205.

 [...] Worked with Leisa Townsley to update the time-dependent CTI 
information in their CTI corrector.  Now includes both the jump in 
November 2003 and the slow recovery to the present. 

1.2 Monitor scientific on-orbit performance of ACIS

  ...  Continued monitoring of ACIS CTI.  Updated CTI monitoring web
page (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/).

 [...] Updated analysis of ExtCalSrc low energy efficiency decrease.
Made available to Paul Plucinsky for use in various ACIS bakeout
presentations and an SPIE paper.

1.3 Update and improve CCD simulation

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

 [...] Submitted a paper to SPIE describing the MIT CTI correction
algorithm that is implemented as part of the CXC pipeline.

  ...  Produced a set of new S1 QE curves for a range of depletion depths.  
These will be used by Alexey Vikhlinin/CXC Cal to test new QE/QEU 
combinations.  A new set of QE and QEU files that include the fix to
the low energy BI QE bug and improvements of high energy BI QE are now 
ready for CALDB release.


2. Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.
A review of the past 60 days of ACIS engineering data shows that the 
instrument remains in a very stable condition.

2.2 Flight software maintenance

 [...] Attempted to load ACIS flight software patch (Rev C of
Flight Software Optional Patches) on May 15.  Attempt was aborted
because of problems verifying the dumped patch list against the
expected values.  Problems were later traced to an out-of-date
file on the ACIS TST workstation.  Patch was successfully loaded
on June 3.

2.3 Instrument science performance

  ...  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 on the possible ACIS bakeout.

 [...] Memo for ACIS telecon group, "Reverse annealing and ACIS
CTI increase during bakeout", summarizes our current knowledge
of bakeout-induced CTI increases, describes a model for the
phenomenon and provides a prediction for a future bakeout. 

 [...] Characterize the performance change from a bakeout by comparing
CTI and FWHM across the ACIS focal plane.  The CCD-to-CCD CTI variations
can be used to represent the bakeout induced CTI change.  Presented
to ACIS telecon group.  


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.  Continued
discussions on improvements in QE and QEU.  Provided new S1 QE files.

  ...  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.

 [...] Due to the previously mentioned problems verifying the flight
software patch list, plans are underway to improve configuration
management of the ACIS workstations in the TST area of the Chandra OCC.

Outreach:

None



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