ACIS Instrument Support - Monthly Progress Report for July 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. 

       * CL6-12 (many ObsIDs) 5 successful runs of no-squeegee cuckoo clocking on I3 Node 3 (focal plane temperature too warm for two 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.

 [...] Created improved trap density maps for S2 at -120C.  Submitted to the CXC Calibration group as part of the CTI simulator.

1.2 Design and characterize alternative CCD readout modes

 [...  Began study of using 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

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

  ...  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.  Presented poster at Chandra Science Symposium (see outreach below).

 [...] 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.

 [...] Processed and archived the last 60 day chunk (2001_097 to 2001_169) of ACIS engineering data.  All parameters are nominal with no evident temporal drift.

2.2 Instrument science performance

 [...] Collected two runs of raw mode continuous clocking data on S0 and S2.

 [...  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

 [...] Assisted J. Holmes in investigation of possible OBC anomaly (corrupted OBSID field).

 [...] Attempted to receive OBSCAT dumps through new "Chaser" interface after previous Java interface withdrawn without warning.

2.3 Participate in Chandra Activities

  ...  Suported dark moon observations on July 26.  Including 

       * Study of instrument safety
       * Command load review
       * Developing software for real-time display of event rates and corner pixel values
       * Real-time support, both command checking and data analysis
       * Preliminary data analysis of optical light leak and X-ray data

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.


Outreach:

Presentations at The High-Energy Universe at Sharp Focus: Chandra Symposium, July 15-17, St. Paul, Minnesota

"The temporal characteristics of the CXO high energy particle background" poster by Catherine Grant

"Chandra Observations of Lensing Clusters of Galaxies" talk by Mark Bautz