ACIS Instrument Support - Monthly Progress Report for February 2003

1. ACIS Characterization

1.1 Characterize and model radiation damage in ACIS CCDs

  ...  Continued running charge injection tests on S2 from the command 
load.  Three tests at two new energies to explore the energy/voltage 
relation.

1.2 Design and characterize alternative CCD readout modes

  ...  Supported charge injection tests on-board with lab verification 
and testing.  Determined new set of DAC values for use with upcoming 
tests on S2.

1.3 Monitor scientific on-orbit performance of ACIS

  ...  Continued analysis of ExtCalSrc data to search for putative QE 
decrease at low energies.  Considering a more complicated model for
the Fe+Mn-L complex with the known line energies and strengths.

  ...  Continued monitoring of ACIS CTI.  Updated CTI web page.  No 
significant changes beyond the long term slow increase.  
(http://space.mit.edu/~cgrant/cti/)

  ...  Continued monitoring of ACIS gain.  Updated gain web page.  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/).

 [...]  Conducted eighth CTI measurement in alternating exposure mode
with frame times of 4.0 and 3.2 seconds (ObsID 60861).  Recalibrated
detrending factor used to remove influence of background on variability
of measured CTI.


1.4 Update and improve CCD simulation

 [...] Modified existing CCD simulator to model response to X-ray 
photons that enter CCD at oblique angles. Also introduced an option 
which allows to explicitely specify intrapixel location of the 
incoming photons, as opposed to random position generation.

  ...  Continued work on improving FI and BI CCD models with a more 
physical representation of CTI.  Wrote code that generates a map of 
traps containing full description of all properties of every trap in a 
CCD.


2. Engineering

2.1 Instrument hardware engineering performance

 [...] Supported the Chandra Risk Management working group meetings

 [...] Supported Chandra thermal working group meetings

  ...  Continue to monitor long term ACIS instrument performance.  

  ...  Continue to support thermal monitoring of the PSMC.  Trend 
remains moderate.

2.2 Flight software maintainence

  ...  Revisions completed on ACIS flight software patches Rev C
documentation.  Distributed to in-house reviewers.

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.  Provided information on sources
of fluorine in ACIS.  Provided engineering evaluation of ACIS bakeout.

  ...  Continued to support charge injection operations by reviewing 
loads and comparing flight data to ground data to select new settings.

 [...] Reviewed ACIS instrument status in a presentation to the ACIS 
IPI team.  Discussed calibration issues with team members.


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.  Discussed
time-dependence of ACIS response and anomalous gain changes for I2.

  ...  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


Outreach:

none