ACIS Instrument Support - Monthly Progress Report for June 2002

1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Continued analysis of no-squeegee cuckoo data.  Work continues on
defining correction factors that would improve over-all performance.  New
code treats each column in the event seaparately.  Preparing results for
presentation at SPIE conference in August.

  ...  Continued running of charge injection tests on S0 from the command
load.  One voltage level tested which injected charge at an energy around
600 eV.

 [...  Began running charge injection tests on I0 from the command load.
Two tests at a voltage level similar to Ti-K energy.

1.2 Design and characterize alternative CCD readout modes

  ...  Supported charge injection tests on-board with lab verification and
testing.

1.3 Monitor scientific on-orbit performance of ACIS

  ...  Continued analysis of ExtCalSrc data to search for putative QE
decrease at low energies.  Updated with more recent data.  Searched for, but
did not find, changes in the L-complex centroid or width with time.
Simulated L-complex and F-K edge to study the effect on fitted centroid and
width.  Searched for, but did not find, a Ti-L line (450 eV) which could
bias the L-complex fits.

  ...  Continued monitoring of ACIS CTI.  No significant changes beyond the
longterm slow increase.  Updated 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.
Updated web page (http://space.mit.edu/~cgrant/gain/).

1.4 Update and improve CCD simulation

  ...  Continued work on detailed physical model of FI CCD including CTI and
sacrificial charge.  Worked on a version of the simulator that can be
incorporated into MARX.

 [...] Analyzed S3 simulated data to compare to LETG data at low energies.
Previous reports of line width discrepancies were due to data analysis
artifacts.  S3 simulation does a good job at representing line width.

2. Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance. Examined
past three months of ACIS housekeeping data. Everything looks nominal.

2.2 Instrument science performance

 [...  Began testing new CC mode bias parameters.  First run is ExtCalSrc CC
mode with old bias algorithm.  More tests in July.  Reviewed parameter
blocks.

  ...  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.

  ...  Continued to develop flight s/w algorithms to implement "Squeegee"
clocking mode and to report precursor charge from ACIS CCDs.

  ...  Participated in ACIS telecons

  ...  Participated in ACIS Operations meeting

  ...  Continued to support charge injection operations by reviewing loads
and comparing flight data to ground data to select new settings.

 [...] Compared instrument gain in CC and TE modes.  Differences were
generally less than 1%.  See ACIS memo #202.

2.3 Participate in Chandra activities

 [...] Supported calibration observation of extremely bright X-ray source
Her X-1 with load reviews and real-time data analysis and monitoring.

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 to maintain ACIS calibration database of ground and flight
data products

 [...] Upgraded the ACIS subassembly database to an Ultra 20

 [...] Participated in CXC Cal discussion of adding new hot pixels to data
analysis lists.  Discussed techniques and did an independent search for new
hot pixels.

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.


New ACIS Memo:

199H - Charge Injection Test on ACIS (updated)
202 - Comparison of Timed Exposure and Continuous Clock Mode Lab Data

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


Outreach:

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