ACIS-S Grating RMFs

About the Chandra Grating Data Archive and Catalog

The Chandra Grating Data Archive and Catalog (TGCat) is a browsable interface to analysis-quality spectral products (binned spectra and corresponding response files). TGCat makes it easy to find observations of a particular object, type of object, or type of observation, to quickly assess the quality and potential usefulness of the spectra with pre-computed graphics or custom-generated plots of binned and combined counts or fluxe spectra. Spectra, responses, event files, and summary products may be downloaded as a package.

TGCat runs standard CIAO tools, but also includes customized extractions for non-standard cases to refine the zeroth order position or to use regions appropriate for extended sources. Non-standard extractions details are provided in "verification and validation" comments for users.

Most public grating observations are available and new ones are added soon after they are released. See the list of of observations not included for exceptions. Many of the observations currently in this list will be included when we add enhanced processing for more difficult cases (multiple sources, very extended sources).

Please consider using the spectrum and responses (PHA, ARF, and RMF files) from TGCat in your analysis.

Repro V (5) data

Script It

The creation of the grating ARF and RMF is now automated.

chandra_repro will now automatically create the RMF and ARF for grating spectra. The results are stored in a tg/ subdirectory of the output directory.

Also, the mktgresp tool will create all the ARFs and RMFs for the grating spectra in a type II PHA file using the default grids and standard calibrations files. Just simply run

unix% mktgresp pha2 evt2 root_filename

where pha2 and evt2 are the filenames of your spectra output from tgextract or tgextract2 and the corresponding event file.

Thread Complete

If you have run chandra_repro or mktgresp then you are done with this thread and may move onto fitting and modeling your spectra. If you need to customize your responses or want to learn more details of the step by step processing steps you can continue with this thread.

Get Started

Download the sample data: 459 (HETG/ACIS-S, 3C 273)

unix% download_chandra_obsid 459 

Early dataset

The data used in this thread was taken very early in the Chandra mission. It was not included in the bulk reprocessing metioned in the Watchout page. The keywords required for analysis with CIAO need to be added by running chandra_repro or r4_header_update.

Make sure that you have set up ardlib to use the bad pixel file for your observation before following this thread.

unix% ls -1 $CALDB/data/chandra/acis/lsfparm/
acisheg-1D1999-07-22lsfparmN0003.fits
acisheg1D1999-07-22lsfparmN0003.fits
acisheg-1D1999-07-22lsfparmN0004.fits
acisheg1D1999-07-22lsfparmN0004.fits
acismeg-1D1999-07-22lsfparmN0003.fits
acismeg1D1999-07-22lsfparmN0003.fits
acismeg-1D1999-07-22lsfparmN0004.fits
acismeg1D1999-07-22lsfparmN0004.fits
acismeg-1D1999-07-22lsfparmN0005.fits
acismeg1D1999-07-22lsfparmN0005.fits
acissleg1D1999-07-22lsfparmN0002.fits
acissleg-1D1999-07-22lsfparmN0003.fits
acissleg1D1999-07-22lsfparmN0003.fits
acissleg-1D1999-07-22lsfparmN0004.fits
acissleg1D1999-07-22lsfparmN0004.fits

Run mkgrmf

Here we create a +1 order HEG gRMF with standard grids:

unix% punlearn mkgrmf
unix% pset mkgrmf order=1
unix% pset mkgrmf grating_arm=HEG
unix% pset mkgrmf outfile=heg_p1.rmf
unix% pset mkgrmf obsfile="acisf00459_repro_evt2.fits[EVENTS]"
unix% pset mkgrmf regionfile=acisf00459_repro_pha2.fits
unix% pset mkgrmf detsubsys=ACIS-S3
unix% pset mkgrmf wvgrid_arf=compute
unix% pset mkgrmf wvgrid_chan=compute
unix% pset mkgrmf clobber=no
unix% mkgrmf
Output File Name (heg_p1.rmf): 
Enter ARF side wavelegth grid [angstroms] (compute): 
Enter channel-side wavelegth grid [angstroms] (compute): 
Enter Grating order (1): 
Name of fits file with obs info (acisf00459_repro_evt2.fits[EVENTS]): 
File containing extraction region (acisf00459_repro_pha2.fits): 
SrcID (1): 
Enter RMF threshold (1e-06): 
Verbosity (0:5) (0): 
Detector Name (e.g., ACIS-S3) (ACIS-S3): 
Enter Grating Arm (HEG|MEG|LEG|NONE) (HEG): 

There are a few details to note:

• The default srcid=1 is used in this example. The srcid is the number of the source in the pha2 file and is used to find the appropriate source position for creating the gRMF. For most observations, there is a single source in the grating observation; if you need to create a gRMF for more than one source in an observation, e.g. to use the output of the Grating Spectra for Multiple ACIS Sources thread, change the srcid to the correct source id for the data.

• The detsubsys parameter is set to the chip on which the 0th order falls. For most observations, this will be ACIS-S3.

• Specifying compute as the grid value is the same as using the default gridding. The default grids for the wvgrid_arf parameter, suitable for most analysis, are listed in the help file. In general, wvgrid_chan is set to be the same as the arf grid.

  It is also possible to run mkgrmf with non-standard grids for the wvgrid_arf and wvgrid_chan parameters, e.g.:

  unix% pset mkgrmf wvgrid_arf="1.0:205.8:0.01"
  unix% pset mkgrmf wvgrid_chan="1.0:205.8:0.01"
  

The contents of the parameter may be checked with plist mkgrmf.

Run the tool for every order and arm you wish to model, changing the order and grating_arm parameters accordingly.

Caveats

unix% dmtype2split infile="acisf00459N004_pha2.fits[tg_part=1,tg_m=1]" outfile="heg_p1_pha.fits[SPECTRUM]" 

unix% pset mkgrmf wvgrid_arf="grid(heg_p1_pha.fits[cols BIN_LO,BIN_HI])" 
unix% pset mkgrmf wvgrid_chan="grid(heg_p1_pha.fits[cols BIN_LO,BIN_HI])"