ACIS Instrument Support - Monthly Progress Report for August 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 telemetry of raw data. 

       * CL13-18 (many ObsIDs) 2 successful runs of no-squeegee cuckoo clocking on I3 Node 3 (focal plane temperature too warm for four runs)

  ...  Continued analysis of no-squeegee cuckoo data.  These observations will be used to study the longest time constant traps (t~seconds).  Limited currently by photon statistics.

1.2 Design and characterize alternative CCD readout modes

  ...  Continued study of charge injection to measure CTI using ACIS electronics in the lab.  Charge can be injected from 100 eV to 6 keV with reasonable precision and can be used to calculate CTI on a pixel by pixel basis.  (see http://space.mit.edu/ACIS/cti_charge_inj.html)  

1.3 Monitor scientific on-orbit performance of ACIS

 [...] Conducted fourth 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.  (see http://space.mit.edu/~cgrant/cti/altexp.html)

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

  ...  Continued study of background flares for multiple SIM and grating positions.

 [...] Updated plots of ACIS gain in the bottom twenty rows of each CCD as a function of time.  All CCDs stable 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.


2. Engineering

2.1 Instrument hardware engineering performance

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

2.2 Instrument science performance

 [...] Collected raw continuous clocking data (CCRaw) on I3 (ObsID 61507) to help characterize structure seen in CC mode bias maps.

 [...  Analyzed results from first two ACIS continuous-clocking raw-mode tests to determine whether the CC bias algorithm can be improved.

  ...  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 operations meetings

 [...] Participated in ACIS telecon

2.3 Participate in Chandra Activities

 [...] Extensive analysis of July dark moon observation, including
       * study of temporal and spatial characteristics of optical light leak
       * comparison of light leak characteristics with pre-flight measurements
       * images and spectra of X-ray data after correction for optical signal

 [...] Participated in planning dark moon observations scheduled for September

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.