Summary of Current Calibration Activities

ACIS

Projects Scheduled for Completion by Sept 2004.

• Improved launch QE for ACIS-S3 chips (An updated ACIS-S3 QE was released in CALDB 2.28 on Aug. 11, 2004)
• Improved QE uniformity for ACIS-I (An updated ACIS-I QEU was released in CALDB 2.28 on Aug. 11, 2004)
• A Tool to account for the spatial variation in the contamination (The tool calcarf.1.0 was posted on the Chandra contributed software page on Oct. 9, 2004 and is the default option in CIAO 3.2 when generating ACIS effective area files.)

Projects Scheduled for Completion by Dec. 2004.

• A new tool to compute ACIS spectral response files (The tool "mkacisrmf" was released in CIAO 3.2 in Dec. 2004)
• Ability of the CXC to generate trap maps (Trap maps have been successfully generated for chips S0, S4, S5, and I3 at T=-120 C)

Projects Scheduled for Completion by June 2005.

• Improved calibration for chips S0, S4 and S5 at T=-120 C

While chips S0, S4 and S5 are primarily used for gratings data, the calibration team is looking into developing the same corrections for these chips as those already developed for the other 7 chips. This includes generating trap maps, applying CTI and time dependent gain corrections, and developing improved responses with mkacisrmf.

• Improved calibration for FI chips at T = -110 C

This includes generating trap maps, applying CTI and time dependent gain corrections, and developing improved responses with mkacisrmf.

• Revised QE for S3

The version of the ACIS-S3 QE released in CALDB 2.28 introduced a small residual feature near the Si-K edge.

Long Term Projects.

• Low energy gain and resolution of S3

There are some residual features in the low energy response of S3 with the CIAO 3.2 version of mkacisrmf.

• Improved ACIS-S3 QE below the Carbon edge
• Improved calibration for BI chips at T = -110 C
• Calibration of ACIS after bake-out

Research continues on accessing the benefits and risks of an ACIS bake-out. A calibration plan is in place if there is project wide agreement to proceed with a bake-out. The analysis of the calibration data and the possible release of new products with take several months to complete.

HRC

Projects Scheduled for Completion by June 2005

• Possible revision to the HRC-I QE.

The present HRC-I QE needs to be verified with the new HRMA effective area file scheduled for release in March 2005. This may necessitate some revisions to the HRC-I QE

Projects Scheduled for Completion by Sept. 2005

• Update the HRC-S de-gap map

An updated de-gap map will improve the LETG/HRC-S dispersion relation in spectroscopic observations and the astrometry in imaging observations.

• An HRC-I rmf to facilitate hardness ratios

Long Term Projects

• Correct the small rotational off-set between the HRC-S exposure map and data on the central plate.

There is a software error in how HRC-S exposure maps are generated, but since only the calibration group looks at extended sources with the HRC-S, this problem is not that relevant to Chandra users.

• Refinements in HRC-I imaging

This may include an updated HRC-I de-gap map and software revisions.

• General monitoring of the HRC detectors (e.g., QE, gain, and bad pixels).
• Continue monitoring of the gain degradation at the aim points of the HRC-I and HRC-S.

The gain at the aim points of both the HRC-I and HRC-S are decreasing due to accumulated dose effects. This may necessitate a change in the aim-points.

LETG

Projects scheduled for completion by Sept. 2004.

• Improve the accuracy of the higher order efficiencies ( An updated LETG transmission file was released in CALDB 2.28 on Aug. 11, 2004)
• Reduce the residuals in the dispersion relation. ( A perl script that reduces the residuals in the LETG/HRC-S dispersion relation and LRFs was posted on the Chandra contributed software page in Dec. 2004)
• Improve the HRC-S QE uniformity map ( A new HRC-S QEU is scheduled for release in CALDB 3.0.1)

Projects Scheduled for Completion by Dec. 2004.

• Refine the HRC-S QE (An updated version of the HRC-S QE is scheduled for release in CALDB 3.0.1)
• Refine the fraction of the total power within the bow tie extraction region. (This is presently scheduled for completion by June 2005)

This will improve the accuracy of absolute flux measurements

Projects scheduled for completion by June 2005.

• Further Improvements in the HRC-S QE

There are still small residual features in the HRC-S QE near the O-K edge. In addition, a new HRC-S QE file needs to be generated that is consistent with the updated HRMA effective area file.

Projects scheduled for completion by Sept. 2005.

• Improve HRC-S gain uniformity map

This will also include a more accurate pulse height filtering and background removal.

Long term projects

• Correct the rotational off-set between HRC-I and ACIS-I gratings data

There is a 0.3 degree tilt between dispersed spectra in the HRC-S and ACIS-S detectors. This is probably a combined software and calibration issue.

• Use cross-calibrations with XMM to verify absolute efficiencies.

Use calibration observations obtained simultaneously with XMM to cross-calibrate, refine and test the efficiencies of the LETGS.

HETG

Projects scheduled for completion by Sept. 2004.

• Complete analysis of relative efficiencies of HETG/ACIS-S and compare MEG and HEG efficiencies. (This analysis was presented at the 2004 Chandra Calibration workshop )

Projects scheduled for completion by March 2005.

• Update MEG and HEG transmission efficiency

A new HETG transmission efficiency file is being developed in conjunction with the new HRMA effective area and ACIS QE and QEU files.

Projects scheduled for completion by June 2005.

• Preliminary report on Chandra/XMM cross calibration.

This report will follow the Chandra/XMM cross calibration workshop being held in March 2005.

Projects scheduled for completion by Dec. 2005.

• Verify high order efficiencies.
• Verify line response functions.

HRMA

Projects Scheduled for Completion by Sept. 2004.

• Improve the effective area near the Ir-M edge

The effects of a small layer of contaminant on the HRMA is being investigated. Several test versions of the HRMA effective area have been generated with different thicknesses for the contaminant. Gratings data are being fit with these test versions of the HRMA effective area along with the latest ACIS QE and QEU files to determine which version produces the best fit with the data. (A new HRMA effective area file will be released in March 2005.)

• Extend the grid of positions used to parameterize the PSF

Additional ray trace simulations are being run to more fully sample how the HRMA PSF varies in the focal plane. Tables of the best fit parameters will be posted on the CXC Calibration Web pages. (The existing tables were expanded on June 24, 2004. Additional ray trace simulations continue to be generated and the final version of the table should be completed by Sept. 2005)

Projects Scheduled for Completion by Dec. 2004.

• Determine if there has been a shift in the HRMA optical axis.(The semi-annual raster scans of ArLac on the HRC-I show evidence that the optical axis of the HRMA has drifted by about 10 arcseconds since launch. The origin of the drift is still under investigation; however, such a small drift has essentially no consequences regarding the analysis of Chandra data.)
• Incorporate new surface scattering model; fold in PSF wing data to improve model inputs. (This project has been delayed until the drift in the HRMA optical axis is better understood. The present completion data is June 2005)

The present version of the HRMA ray trace code underestimates the large angle scatter of the mirrors as measured by a long exposure of Her X-1. New scattering models are being investigated to determine if they accurately predict the empirical fits to the wings of the PSF as measured by the Her X-1 data.

• A refined model for the ACIS PSF without pile-up. (This project has been delayed. The present completion data is June 2005)

The outer core and wings of the ACIS PSF are slightly broader than those in the HRC PSF. This requires a separate calibration product for the ACIS PSF.

Projects Scheduled for Completion by March 2005.

• Updated HRMA effective area file

Projects Scheduled for Completion by June 2005.

• Incorporate new surface scattering model; fold in PSF wing data to improve model inputs.

• A refined model for the ACIS PSF without pile-up.
• Analyze pile-up observations

A series of 5 ACIS-S observations of the pulsar PSR0437-4715 with different frame times are scheduled for the first three months of 2005. These observations will be analyzed to verify spectral pile-up models and better calibrate ACIS imaging with pile-up

Projects Scheduled for Completion by Sept 2005.

• Complete the raytrace simulations used to parameterize the PSF

Long Term Projects

• Access telescope positional accuracy

The HRMA is not a thin lens, so the plate scale is not perfectly linear in the focal plan of the mirrors. However, studies have shown that distortions induced by the mirror optics are less than 0.5" over the field-of-view of the detectors. A memo describing this study will be posted on the CXC Calibration web pages.

• Refine optics alignment model to improve deconvolutions using the on-axis PSF

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