ACIS Instrument Support - Monthly Progress Report for May 2005

1.  ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ... Finished planning and preparation for next set of cold irradiation
and bakeout lab tests at GSFC.  After verification and a dry run,
equipment was shipped to GSFC.

  ... Performed a set of cold irradiation and bakeout lab tests
at the GSFC Van de Graaf accelerator from May 9 - 26.  Proton 
energies used for irradiation were from 100 - 400 keV.  Five
CCDs were irradiated and then put through an 8-hour bakeout cycle.
One CCD was irradiated and then put through an isochronal annealing
test with multiple bakeout temperatures and dwell times.

  ...  Began analysis of cold irradiation and bakeout lab test data.
Initial results will be presented at the upcoming ACIS telecon on
15 June.

  ...  Finished fine tuning calibration products for S3 BI CCD
CTI correction (-120C only).  Products have been handed over to 
Glenn Allen, CXC SDS, to test implementation in acis_process_events.

  ...  Continued taking a series of data in full-frame raw mode for
performance verification and monitoring.  Three ObsIDs this month with
data in both the ACIS-I and ACIS-S configurations.

1.3 Monitor scientific on-orbit performance of ACIS

  ...  Continued monitoring of ACIS CTI, gain, trailing pixel pulseheight,
detector efficiency and spectral line centroid and width.  Updated 
monitoring web pages.
(linked from http://space.mit.edu/~cgrant/monitor.html)

  ...  Finished preparing and presented ACIS SI team report at the Chandra 
Quarterly Review.

1.4 Update and improve CCD simulation

  ...  Continued effort to improve fidelity of the BI CCD simulator
at low energies.  Worked on the BI CCD simulator to make the response 
function fit experimental data from LETG around silicon edge.


2.  Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.
ACIS remains stable, with no untoward trends noted in the past 60 days 
engineering telemetry.  The latest focal plane cooling test leads to the 
conclusion that, although the ISIM temperatures continue to rise due to 
the degradation of thermal surfaces, the ACIS radiators themselves remain 
-- within our ability to measure these things -- at their as-launched 
efficiency.

2.2 Flight software maintenance

  ...  Continued study of the ObsID 5645 anomaly (SPR 138, M05040701).
This is a flight anomaly that surfaced during OBSID 5645 (March 30, 2005)
when a single ACIS telemetry packet was missing and garbage was output in 
its place.  Examining past data, 13 other instances have been identified 
since January 2000.  The most likely explanation is two tasks calling a 
non-reentrant routine simultaneously.  The anomaly has been reproduced 3 
times on the ACIS engineering unit and a software patch is being developed 
and tested that should eliminate the problem.

2.3 Instrument science performance

  ...  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.


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 modeling discussion group.

  ...  Continued to maintain ACIS calibration database of ground and 
flight data products.


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.

  ...  Continued work on improving configuration management of the ACIS
workstations in the TST area of the Chandra OCC.  


Outreach:

None


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