ACIS Instrument Support - Monthly Progress Report for November 2003

1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

 [...  Continued taking a series of data in full-frame raw mode for
performance verification and monitoring.  One ObsID this month
with data in the ACIS-I configuration.

1.2 Monitor scientific on-orbit performance of ACIS

 [...] Extremely hard CME caused an extended shutdown of ACIS starting
at the end of October.  The measured CTI for both the FI and BI CCDs suffered
a step function increase during this time equivalent to the CTI increase
normally seen over an entire year.  Only the parallel CTI in the imaging
array seems affected - parallel CTI in the framestore and serial CTI
remain unchanged.  This implies the damaging radiation was soft, even
though ACIS was in the HRC-S position during this period.  The high 
energy particle background remains anomalously low, so the true radiation
damage estimate may change.  Analysis is ongoing.  New web page.
(http://space.mit.edu/~cgrant/cti/change/change.html)

  ...  Continued analysis of ExtCalSrc data to study efficiency 
decrease at low energies.

  ...  Continued examining a new model for the ACIS contaminant suggested
by Dan Dewey which could reconcile the discrepancy between the
absorption time dependence measured by the cal source and by LETG.

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

 [...] Updated analysis of alternating exposure mode data to match
new CTI analysis and to add new data sets originally missed.
(http://space.mit.edu/~cgrant/cti/altexp.html)

  ...  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/).

 [...  Began program to monitor the fraction of the charge loss
re-emitted into the first trailing pixel.  This quantity is dependent
on the trap time constants and has been relatively constant over
the mission.  A web page is under development.

 [...] Presented ACIS status for Chandra quarterly review/IAR

1.4 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.
No new anomalies or trends

  ...  The engineering team continues to support the debates over the 
possible instrument bakeout.

2.2 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.
Discussed possibilities for ground OBF thermal tests and likelihood
of contaminant polymerization by low energy protons.


3. CXC Support

3.1 Provide user support

 [...] Participated in GLAST instrument operations team visit.  
Presentation on the role of the ACIS instrument team and interaction 
with CXC ACIS team.

  ...  Updated ACIS memo listing calibration ObsIDs and observation
characteristics (ACIS Memo #165).

 [...] Email discussion with HST/STIS team member about the calibration
of the ACIS CTI model.

 [...] Solved user data analysis problem.  Solution was to use smaller
RMF energy bins than the default 10 eV.

3.2 Provide data analysis support

 [...] Participated in CXC Cal/Ops RMF 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.


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