ACIS Instrument Support - Monthly Progress Report for August 2000


1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Continued quantum efficiency calibration of radiation damaged CCD, w457c1.  Final results will be used to characterize the uniformity of CCD QE after radiation damage.

  ...  Conducted tests in the command load for the 16-row squeegee mode with no initial flushing frames.  Bias frames will be used to measure trap time constants.  Results indicate less initial charge than expected - analysis on-going.

       * 17 August - Ran 16-row squeegee with no initial flush frames on flight device I2 (L8, ObsID 61962)


1.2 Define and characterize alternative CCD readout modes

  ...  Conducted real-time tests of squeegee readout mode on flight device S0.

       * 12 August - ran "subarray" squeegee mode with 2-row squeegee, 8-times slower readout with a 256-row subarray near the top of the array (R8, ObsID 61968)

  ...  Conducted tests of squeegee mode on flight device I0 in the command load.

       * 30 August - ran "subarray" squeegee mode with 2-row squeegee, 8-times slower readout with a 256-row subarray near the top of the array (L9, ObsID 61949)

  ...   Analysis of flight squeegee results on-going.  Preliminary results can be found at http://space.mit.edu/~cgrant/squeegee/squeegee.html.  Results for both S0 and I0 are as expected based on lab results.

  ...  Completed draft of memo outlining the performance and efficiency trade-offs of the tested squeegee modes (ACIS Memo #191)

  ...  Continued lab testing of squeegee readout mode using w459c1.

1.3 Monitor scientific on-orbit performance of ACIS

  ...  Continued monitoring of ACIS CTI.

1.4 Update and improve CCD simulation

  ...  Continued recalibration of S3 QE using sub-assembly and XRCF data and more accurate source/detector models.

  ...  Continued effort to model the volume occupied by a charge packet as a function of signal charge in the CCD pixels.  The CCD model and the flight software CTI corrector requires this relationship for accurate results.

  ...  Continued work on introducing FI CCD CTI effects in the CCD model.


2. Engineering

2.1 Instrument hardware engineering performance

 [...]  Reviewed full ACIS engineering data received over the past year, made histograms of same, and revised MIT document 36-02215 to show currently revised red and yellow limits proposed to be used by the FOT in monitoring the instrument.

2.2 Flight software maintenance


2.3 Instrument science performance

  ...  Continued quick-look processing of all ACIS science runs, using EHS telemetry supplied by the GOT.

  ...  Continued to publish the "annotated DOT" timeline reports.

  ...  Continued testing of flight S/W algorithms to estimate correction for charge lost to medium time-constant CCD charge traps.

 [...] Designed and tested web interface to ACIS real-time data

2.5 Participate in Chandra activities

 [...] Supported squeegee readout mode tests on 12 August, 17 August and 30 August including load and CAP review and real-time data analysis support.


3. CXC Support

3.1 Provide user support

  ...  Continued to assist the CXC MTA in CTI monitoring and background correlations.  Worked with software designers to improve accuracy of CTI results.

  ...  Updated ACIS memo listing calibration ObsIDs and observation characteristics (ACIS Memo #165).

3.2 Provide data analysis support

 [...] Revised several sections of "ACIS Telemetry Products: Level 0 to CXC Archive ICD" and "ACIS Telemetry Products: Level 1 to CXC Archive ICD"

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:

191 - Choosing an ACIS Squeegee Mode 

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