ACIS Instrument Support - Monthly Progress Report for July 2004

1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Continuing test of our CTI/background relation by running a series 
of alternating exposure mode observations with a grid of exposure times.  
In July there were two runs with frametimes of 1.5s and 3.5s, alternating 
with a standard frametime of 3.2s.  These runs complete the set.  The 
non-linear effect appears to be small, so a second set of runs has been 
started to increase statistics.

1.2 Monitor scientific on-orbit performance of ACIS

  ...  Continued monitoring of ACIS CTI.  Updated CTI monitoring web page. 
(http://space.mit.edu/~cgrant/cti/)

  ...  Continued monitoring of ACIS gain.  All CCDs stable with a slow 
decline in gain slope (ADU/eV) except for I2 which continues to vary.
(http://space.mit.edu/~cgrant/gain/)

 [...  Set up new web pages for monitoring trailing pixel pulseheight, 
which is sensitive to the trap time constants, and detector efficiency at 
high and low energies.  These will be updated on the same monthly schedule 
as the CTI and gain web pages.
(http://space.mit.edu/~cgrant/trail/)
(http://space.mit.edu/~cgrant/qe/)

1.3 Update and improve CCD simulation

  ...  Continued work on improving FI and BI CCD models and CTI simulation 
code.


2. Engineering

2.1 Instrument hardware engineering performance

  ...  Continue to monitor long term ACIS instrument performance.  ACIS 
engineering data continues to be stable.

2.2 Flight software maintenance

  ...] Completed investigation of the ACIS anomaly during ObsID 5008 on 
June 22 in which an uncommanded reset of all the FEPs terminated a science 
run.  Analysis of the telemetry and a dump of the BEP memory indicate that 
the most likely explanation is a single-event upset in an Actel FPGA, 
either on the BEP or on the DEA Interface Board.  Since it seems unlikely 
for this or a similar failure to reoccur, no action is being taken at this 
time.  MIT Software Problem Report 136 documents the investigation and the 
probable cause and is available online.  
(ftp://acis.mit.edu/pub/SPR136-1.0.pdf)

 [...] Ran CAP 923 on July 15 to dump ACIS BEP memory, warmboot and redump
the memory as part of the ACIS anomaly investigation.  Ran nominally.  No
evidence for degradation of flight software; no unexpected changes either 
in code or in static variables.

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.

 [...] Participated in ACIS telecons on the possible ACIS bakeout.  
Discussions of the effect of contaminant on OBF thermal properties.  ACIS 
bakeout has been postponed indefinitely.

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.  Continued 
discussions on improvements in QE and QEU calibration.  Began task list 
for post-bakeout calibration effort.

  ...  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