Cycle 11 Grating RMFs/ARFs

NOTICE TO CY11 PROPOSAL PLANNERS -- FINAL RELEASE

This is the promised final release of the CY11 Grating ARF and RMF files.

The Grating ARFs and zeroth order ARFs below have been updated to include a new and better model of the HRMA axial effective area, which applies to all configurations. (We have elected NOT to upgrade the ACIS Optical Blocking Filter contamination model, which is under further investigation.) The new hrma files is named "hrmaD1996-12-20axeffaN0008.fits" and is being released with CalDB 4.1.1. An incumbent adjustment of the HETG grating efficiencies is also being released, to maintain the HEG and MEG 1st-order cross-calibration accuracy.

The update to the HRMA model involves a more self-consistent application of small contamination layers on the iridium mirror surfaces, and uses a different method of weighting the HRMA pre-launch calibration data. The result of the change is an improvement in high-temperature cluster modeling with the HRMA/ACIS-S and HRMA/ACIS-I configurations, with derived plasma temperatures more consistent between these two internal configurations, and better cross-calibration with the XMM telescope as well.

The GARFs and ARFs below NO LONGER include the appendage "_p.garf" or "_p.arf" because these are now the final *.garf files. Please delete the *cy11_p.garf files completely, and download the new *cy11.garf files below.

We have prepared sample grating RMFs and corresponding ARFs for proposal planning purposes. As in the CY09 release, all of the GRMF files below were built with mkgrmf, using the latest LSF parameter data for the HETG/ACIS-S, LETG/ACIS-S, and LETG/HRC-S configurations. In all cases, the grating pixel randomization, RAND_TG is set to 0 pixels (turned off).

The ACIS-related gARFs were built with the CIAO script fullgarf, using PHA2 files from specific archival observations and the appropriate GRMF energy grid as the seed energy grid. They therefore include dither, and do not have exactly the nominal aimpoints as their source positions. The configuration information, including SIM_Z position and ObsID numbers, are included in the GARF headers.

The ACIS-S configuration effective areas (*.garf or *.arf) were derived using CIAO 4.1.1, CALDB 4.1.1, including the latest ACIS contamination model file acisD1999-08-13contamN0004.fits, with the time delay value set at 390268865.184s, corresponding to the UTC date 2010-05-15T00:00:00, or half-way through the CY11 observation period. For the HRC-S configurations, all effective areas were derived from CIAO as well, using the latest QE and QE uniformity calibrations.

To download individual files, <Shift>-click on the filename. The complete set of responses is available as a gzipped tarfile from the anonymous FTP site asc.harvard.edu in the directory /pub/caldb/CY11/.

Caveats and Notes

1. These gARFs and gRMFs are for proposal planning purposes only. They should not be used for analysis of any real Chandra data. The Grating Spectroscopy threads give instructions for building an observation-specific gRMF and gARF.

2. LETG/HRC-S proposal planners: the above gRMFs and gARFs for the LETG/HRC-S configuration must be used in gRMF/gARF pairs for appropriate response settings to be employed. The LETGS group also has convolved gRMFs and gARFs, known as "gRSP" files, available for download on the LETGS Effective Area webpage. That webpage explains the proper use and interpretation of these files.

3. A Note concerning the LETGS Encircled Energy Fraction: The LETG/HRC-S configuration requires that an encircled energy fraction, or EEARF, be considered in order to apply the appropriate response for these grating data. With the release of CalDB 2.27 in July 2004, this correction is actually included in the GRMF, and hence should not be included in the GARF. Therefore, the LETG/HRC-S GARFs (all orders) for LETG/HRC-S have been built so that the encircled energy fraction is not applied to the GARF. HOWEVER, in order for the users results to agree with the results of PIMMS for this configuration, one must either use the GRMF and GARF in tandem (in XSPEC, Sherpa, or similar fitting environment), or one must apply the encircled energy fraction to the GARF. The GARFs may be modified using the script factor_rsp, which is described in the documentation file factor_rsp.txt. The script may be [shift-click] downloaded for use in any shell with isis-script in one's path, such as a shell configured for CIAO 4.1.1.