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Chandra Calibration Status. Summary The gratings and mirrors are very well calibrated at this time and there are no time-dependent effects as far as we can tell.

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chandra calibration status

Chandra Calibration Status

Summary

The gratings and mirrors are very well calibrated at this time and there are no time-dependent effects as far as we can tell.

Most activities in the calibration group are centered on improving the calibration of the detectors and monitoring the time-dependence response of the detectors.

At present we have a single time-independent QE for each ACIS chip and HRC MCP, however, the transmission of the contaminate on ACIS is time-dependent.

The spectral response of both ACIS detectors and both HRC detectors is also treated in a time-independent manner.

The ACIS gains are calibrated every 3 months and the HRC gains are calibrated once per year.

There are two sets of trap maps for each ACIS FI chip (one set for the first 4 years and one set for the second 4 years) and only one set of trap maps for the ACIS BI chips.

slide2

Calibration Updates Since the Last CUC Meeting

ACIS

Gain correction files for epochs 25 and 26 (Nov 2005-May 2006) were released in CALDB 3.2.4 on Nov. 7, 2006.

A set of cti-corrected (serial and parallel) calibration products for the BI chips at T=-120 C was released in CALDB 3.3 on Dec. 18, 2006. These products include: trap maps, QE maps, response files, and OSIP files.

A revised version of the ACIS QE with corrections near the SI-K edge was released in CALDB 3.3

Gain correction files for epoch 27 (May 2006-Nov 2006) were released in CALDB 3.3

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5. Gain correction files for epoch 28 (Dec. 2006-Feb. 2007 will be released in CALDB 3.4
  • Updates to the standard set of ACIS background images will be released in CALDB 3.4.

HRC

  • A set of gain correction files (one for each year) was released in CALDB 3.3
  • A rmf for the HRC-S was released in CALDB 3.3. This is required to make energy invariant hardness ratio images.
  • Further refinements to the set of HRC-I gain correction files will be released in CLDB 3.4.
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HRMA
  • A verified Linux version (phase 1.0) of the SAOSAC software was delivered to Data Systems in Feb. for integration into Level III processing.
  • A more portable version (phase 2.0) of the SAOsac raytrace software will be available to the public in May.
  • A memo was posted on the calibration web pages describing the drift of the optical axis since launch.
slide5
LETG
  • An updated HRC-S QE with correction near the O-K edge is scheduled for release in CALDB 3.4.

HETG

  • Updated OSIP files (required for cti-corrected data for the BI chips) were released in CALDB 3.3
current calibration activities acis
Current Calibration ActivitiesACIS
  • Improve graded mode calibration which cannot be cti-corrected in the same way as faint mode data.
  • Improve CC mode calibration. This primarily relates to gratings data.
  • Improve calibration at T=-110 C.
  • Fitting the ECS data over the course of the mission shows that there has been an increase in the width of the lines by 15-35 eV (sigma). A metric is being devised to signal when a new set of trap maps will be necessary.
  • Possible temperature-dependent cti-corrections.
  • Possible revisions to the contamination model.
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HRC
  • Update the HRC-I de-gap map using the AO8 raster scan of Capella.
  • Update the low energy HRC-I QE based on the recent LETG/HRC-I observations of HZ43.
  • Update the HRC-I QE map using the off-axis observations of RXJ1856.
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LETG
  • Generate a set of finer grid time-dependent gain correction files (one per year).
  • Improve the HRC-S QE below the C-K edge.
  • Investigate the cause of the 5% drop in count rate in the LETG/HRC-S observations of HZ43 at low energies (i.e., on the outer MPCs).
  • Derive an improved pulse-height-based background rejection filter using the fine resolution time-dependent gain corrections.
  • Further improve the HRC-S de-gap coefficients tables to include empirical corrections from emission line and continuum sources.
  • Incorporate the non-linearity in the LETG/HRC-S dispersion relation into the line response function.
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HETG
  • Use HETG/ACIS-S data taken in CC mode to improve CC mode calibration.
  • Improve higher order efficiencies.

HRMA

  • Finish analysis of ACIS piled-up observations and post a memo on the calibration web pages.
  • Continue development of the Linux version of the raytrace software
  • Release the enclosed count fraction (ECFs) from elliptical rather than circular apertures.