ACIS Instrument Support - Monthly Progress Report for March 2001


1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Continued collection of raw data in "cuckoo" clocking mode which allows for more efficient data telemetry. 

       * L58, L60, L62-64 (many ObsIDs) 5 successful runs of 16-row squeegee in cuckoo clocking mode on I3 Node 0

       * L59, L61 (ObsIDs 61710, 61698) 1 successful run of 8-row squeegee in cuckoo clocking mode on I3 Node 3 (focal plane temperature too warm for one run)

  ...  Continued analysis and modeling of cuckoo squeegee data.

       * Wrote extensive memo on ACIS CTI correction including modelling and correction algorithms.  (http://space.mit.edu/ACIS/iacis.html)  Summarizes our current knowledge of trap densities, time-constants and charge loss.  Outlines two correction approaches and presents possible performance improvements.


1.2 Monitor scientific on-orbit performance of ACIS

  ...  Continued monitoring of ACIS CTI. No significant changes detected.

 [...] Conducted third CTI measurement in alternating exposure mode with frame times of 4.0 and 3.2 seconds.  This test will be used to calibrate and search for time variation in the detrending factor used by MIT and CXC to remove the influence of background variability on measured CTI.  Memo forthcoming.

  ...  Continued effort to correlate ACIS CTI increases with attenuated fluence from Chandra Radiation Model.


2. Engineering

2.1 Instrument hardware engineering performance

  ...  Continued to monitor hardware operations.  No problems.

2.2 Instrument science performance

 [...  Developed ACIS flight S/W patch to report precursor charge from front-end processors. Tested patch on ACIS engineering unit.

  ...  Continued daily quick-look processing of ACIS telemetry.

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

  ...  Continued to test flight s/w algorithms to estimate charge lost from FI CCDs due to charge traps, using results from the ongoing series of "Squeegee-Cuckoo" tests.

  ...  Continued to support the Web interface to ACIS real-time data.

2.3 Participate in Chandra Activities

 [...] Supported squeegee and the new cuckoo clocking mode tests including load and CAP review, and real-time command checking and data analysis.

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

 [...] Consulted with CXCDS personnel on issues relating to ACIS timing in continuous-clocking mode.


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 Memos:

ACIS CTI Correction Report

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