ACIS Instrument Support - Monthly Progress Report for May 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. 

       * L70-75 (many ObsIDs) 5 successful runs of 8-row squeegee in cuckoo clocking mode on I3 Node 3 (focal plane temperature too warm for one run)

       * CR1 (ObsID 61620) first real-time test of cuckoo clocking mode without squeegee on S0 Quad D was successful.  Future runs on I-array CCDs are being planned.  These observations will be used to study the long time constant traps.

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

  ...  Continued study of a ground-based CTI correction algorithm.  New version allows for variable trap density along each CCD column and uses a 1024x1024 trap density map for each CCD.

 [...] Penn State and MIT ACIS team members met with representatives of CXC (SOT, Cal, DS and SDS) to discuss ACIS CTI correction models and methods on 02 May 2001.

       * Presented and discussed report on CTI correction approaches and possible implementation schemes.

       * Committee recommended implementation of an algorithm including the best of the Penn State and MIT CTI models.  

       * Assisted the CXC in developing the specifications for a tool to correct for CTI.

1.2 Monitor scientific on-orbit performance of ACIS

  ...  Continued monitoring of ACIS CTI. Updated CTI web page (http://space.mit.edu/~cgrant/cti/cti120.html).  No significant changes detected.

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

  ...  Continued study of background flares for multiple SIM and grating positions.  Flares are much more common when ACIS is in the focal plane without the gratings inserted, however a small number flares have occured with the HETG inserted or when ACIS is in the HRC-S position.

1.3 Update and improve CCD simulation

  ...  Continued process of including our model of radiation damage into CCD simulator for FI CCDs.  The CCD simulator including CTI effects will be handed over the CXC in July.


2. Engineering

2.1 Instrument hardware engineering performance

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

 [...] Tested the newly built flight AE boards that are intended to provide the full complement for the engineering test model in NE-80.  The boards exhibited the usual odd behaviours but should suffice for the purposes of the engineering unit - loading and running pram patches.

2.2 Instrument science performance

 [...] Published report on "Anomalous ACIS Pixel Values" on 07 May.  Includes characterization of the anomalously low bias values which produce the appearance of hot pixels in event data.

 [...  Tested parameter blocks which include a median filter in bias calculation (Bias Tests BL1-8).  Once test is determined successful, all parameter blocks will include the median filter to prevent the occurence of anomalously low bias values.

  ...  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 cuckoo clocking mode tests including load and CAP review, and real-time command checking and data analysis.  Supported real-time commanding for CAP726 on 22 May.

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


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:

"Anomalous ACIS Pixel Values", May 7 2001, 
  http://acis.mit.edu/asc/pixanom1.pdf

Outreach for Bautz:

May 1 01	Interview with John Schmitt of Air & Space Magazine
		on development of ACIS

May 4 01	Talk at MIT Lincoln Labs: The Chandra X-ray Observatory