LETG/ACIS-S Grating ARFs
CIAO 4.14 Science Threads
fullgarf is a script that creates a grating ARF for a particular order and grating of an observation. While the mkgarf tool will create a grating ARF for an individual chip given an aspect histogram, this script creates ARFS for each chip, creating aspect histograms as necessary. The script then combines the individual ARFS into one for the full array.
To create grating ARFs for an LETG/ACIS-S observation.
- About the Instrument: ACIS & LETG
- Analysis Guide for Chandra High Resolution Spectroscopy: an in-depth discussion of grating analysis.
Continuous Clocking Mode why topic: additional information for users working with CC-mode data.
ACIS QE Contamination why topic: correcting for the change in low-energy ACIS QE associated with the deposition of one or more materials on the ACIS detectors or optical blocking filters.
Last Update: 31 Jan 2022 - Review for CIAO 4.14. Added section about repro5 datasets.
- About the Chandra Grating Data Archive and Catalog
- Repro V (5) data
- Script It
- Get Started
- Determine the Orders of the Observation
- Run fullgarf
- Parameter files:
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
Datasets which have been processed as part of Repro V (5), and those recently obtained data processed with ASCDSVER=10.8.3 and newer include grating ARFs and RMF files for the source spectrum extracted in the pha2 file. These files are located in the primary/responses directory.
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.
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.
Download the sample data: 1198 (LETG/ACIS-S, 3C 273)
unix% download_chandra_obsid 1198
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.
It is assumed that you have created a gRMF for your observation by running the Create Grating RMFs for ACIS-S Observations thread, which is called rmf.fits.
Using the mask file
To make sure that the gARF file is correct, set the maskfile parameter to the observation-specific msk1.fits file. If you are working with continuous-clocking (CC) mode data, be sure to read the ACIS Pipeline-Processed Mask Files caveat as well.
Determine the Orders of the Observation
An ARF needs to be calculated for each order in the observation. We can use dmlist to examine the pha2 file and determine how many orders there are:
unix% dmlist acisf01198_repro_pha2.fits"[cols tg_m,tg_part]" data,clean # TG_M TG_PART -3 3 -2 3 -1 3 1 3 2 3 3 3
The tg_m column indicates the order of the observation (+/- 1, +/- 2, +/- 3) and the tg_part column indicates the grating (1 = HEG, 2 = MEG, 3 = LEG). The six rows (all +/- orders for LEG) for the LETG observation are shown in .
It is necessary to run fullgarf for each order that will be modeled, up to six times (once for each row in the PHA file).
For row 2, LEG, order = -2:
unix% punlearn fullgarf unix% pset fullgarf phafile=acisf01198_repro_pha2.fits unix% pset fullgarf pharow=2 unix% pset fullgarf evtfile=acisf01198_repro_evt2.fits unix% pset fullgarf asol=@pcad_asol1.lis unix% pset fullgarf engrid="grid(rmf.fits[cols ENERG_LO,ENERG_HI])" unix% pset fullgarf badpix=acisf01198_repro_bpix1.fits unix% pset fullgarf maskfile=acisf01198_000N003_msk1.fits unix% pset fullgarf dafile=CALDB unix% pset fullgarf rootname=acisf01198
In some rare cases, there will be more than one aspect solution file (pcad_asol1.fits) for an observation. All the files must be input to the asol parameter, either as a list or a stack. Here we use:
unix% cat pcad_asol1.lis pcadf01198_repro_asol1.fits
Now run the tool:
unix% fullgarf Will use /home/username/cxcds_param4/fullgarf.par for the parameter file. /home/username/cxcds_param4/fullgarf.par contains 15 parameters . . . Input PHA file (Type I or II) (acisf01198_repro_pha2.fits): Row in Type II PHA file (ignored if Type I) (0:99) (2): Event file (acisf01198_repro_evt2.fits): Aspect offsets file (@pcad_asol1.lis): Energy grid spec (grid(rmf.fits[cols ENERG_LO,ENERG_HI])): Dead time correction factor; ACIS->evt file; HRC -> dtf file (): Bad pixel file; (filename|NONE|CALDB) (acisf01198_repro_bpix1.fits): Output rootname (acisf01198): NONE, or name of ACIS window mask file (acisf01198_000N002_msk1.fits): Getting the pha file type . . . Grating arm is LEG, order=-2 Source location is X=4162.240234375, Y=4084.679931640625 Detector is ACIS Will run asphist for ccd_id= 4 5 6 7 asphist infile=@pcad_asol1.lis outfile=acisf01198_ah4.fits evtfile=acisf01198_repro_evt2.fits[ccd_id=4] dtffile= asphist infile=@pcad_asol1.lis outfile=acisf01198_ah5.fits evtfile=acisf01198_repro_evt2.fits[ccd_id=5] dtffile= asphist infile=@pcad_asol1.lis outfile=acisf01198_ah6.fits evtfile=acisf01198_repro_evt2.fits[ccd_id=6] dtffile= asphist infile=@pcad_asol1.lis outfile=acisf01198_ah7.fits evtfile=acisf01198_repro_evt2.fits[ccd_id=7] dtffile= Finished creating aspect histograms for ccd_id= 4 5 6 7 Will run mkgarf for the same ccd_id list mkgarf detsubsys=ACIS-S0 order=-2 grating_arm=LEG outfile=acisf01198_S0_LEG_-2.fits asphistfile=acisf01198_ah4.fits[ASPHIST] engrid=grid(rmf.fits[cols ENERG_LO,ENERG_HI]) osipfile=CALDB dafile=CALDB pbkfile= maskfile=acisf01198_000N002_msk1.fits mode=hl verb=0 mkgarf detsubsys=ACIS-S1 order=-2 grating_arm=LEG outfile=acisf01198_S1_LEG_-2.fits asphistfile=acisf01198_ah5.fits[ASPHIST] engrid=grid(rmf.fits[cols ENERG_LO,ENERG_HI]) osipfile=CALDB dafile=CALDB pbkfile= maskfile=acisf01198_000N002_msk1.fits mode=hl verb=0 mkgarf detsubsys=ACIS-S2 order=-2 grating_arm=LEG outfile=acisf01198_S2_LEG_-2.fits asphistfile=acisf01198_ah6.fits[ASPHIST] engrid=grid(rmf.fits[cols ENERG_LO,ENERG_HI]) osipfile=CALDB dafile=CALDB pbkfile= maskfile=acisf01198_000N002_msk1.fits mode=hl verb=0 mkgarf detsubsys=ACIS-S3 order=-2 grating_arm=LEG outfile=acisf01198_S3_LEG_-2.fits asphistfile=acisf01198_ah7.fits[ASPHIST] engrid=grid(rmf.fits[cols ENERG_LO,ENERG_HI]) osipfile=CALDB dafile=CALDB pbkfile= maskfile=acisf01198_000N002_msk1.fits mode=hl verb=0 Finished creating grating arfs for ccd_id= 4 5 6 7 dmarfadd @thisfile.istemporary acisf01198LEG_-2_garf.fits fullgarf finished.
You may also see an aspect-related error from mkgarf; it is explained in the fullgarf bug page. The content of the parameter file may be checked using plist fullgarf.
The script is run in a similar way for the remaining rows.
At this point, you should have the spectra, gARFs, and gRMFs necessary for fitting the data. The Fitting Grating Data thread shows how to load the data and responses, define a model, and fit the spectra.
In order to use Gaussian statistics to fit a model to a dataset, it is often necessary to "group" the data - i.e. combine channels until you have enough counts. Before fitting the data in Sherpa, read the Grouping a Grating Spectrum thread for more information.
Parameters for /home/username/cxcds_param/fullgarf.par phafile = acisf01198N004_pha2.fits Input PHA file (Type I or II) pharow = 2 Row in Type II PHA file (ignored if Type I) evtfile = acisf01198N004_evt2.fits Event file asol = @pcad_asol1.lis Aspect offsets file engrid = grid(rmf.fits[cols ENERG_LO,ENERG_HI]) Energy grid spec dtffile = Dead time correction factor; ACIS->evt file; HRC -> dtf file badpix = acis_1198_new_bpix1.fits Bad pixel file; (filename|NONE|CALDB) rootname = acisf01198 Output rootname maskfile = acisf01198_000N003_msk1.fits NONE, or name of ACIS window mask file (dafile = CALDB) NONE, CALDB, or name of ACIS dead-area calibration file (osipfile = CALDB) NONE or Name of fits file with order sorting info (clobber = no) Clobber existing output files? This is passed to ALL child processes. (verbose = 0) Control the level of diagnostic output. 0=>least. (mode = hl) Mode flags. Set to 'ql' to enable querying, 'hl' to suppress.
|23 Dec 2004||updated for CIAO 3.2: canned gRMFs are no longer available in the CALDB|
|06 Dec 2005||updated for CIAO 3.3: the fullgarf script has been updated to version 3.3.1 for the new asphist tool syntax; corresponding changes to screen output|
|01 Dec 2006||reviewed for CIAO 3.4: no changes|
|26 Feb 2007||fullgarf v4.0.1: Four new parameters have been added, all of which are used by the mkgarf tool: pbkfile, dafile, osipfile, and maskfile; see "ahelp fullgarf" for details on each new parameter. Added ACIS dead area correction section|
|23 Jan 2008||updated for CIAO 4.0: fullgarf v4.1.1 (parameter updates for applying ACIS dead area correction, which is turned on by default); ACIS QE contamination link moved to "Related Links" section; removed outdated calibration updates|
|30 May 2008||fullgarf v4.1.3 (Unix head and tail commands replaced by pget and dmkeypar); thread images are inline|
|12 Feb 2009||updated for CIAO 4.1: "ARDLIB warning ... Assuming the first "interesting" extension." no longer printed; input data must have a CTI_APP keyword|
|19 Feb 2009||added Fitting section|
|06 May 2009||check the version of the CIAO scripts package instead of the individual script|
|01 Jun 2009||fullgarf updated in 01 Jun 2009 scripts package: If bad pixel file is not supplied, use the one from the CALDB. Previously, the script would set the bad pixel file to "NONE" in this case.|
|16 Jun 2009||added About the Chandra Grating Data Archive and Catalog section|
|12 Jan 2010||updated for CIAO 4.2: calibration update - the ACIS QE contamination model has been upgraded to vN0005.|
|05 Apr 2010||updated for CALDB 4.2.1: calibration update - the LETG grating efficiency has been upgraded to vN0006.|
|15 Dec 2010||updated for CIAO 4.3: new ACIS contamination calibration file|
|01 Mar 2011||CALDB 4.4.2 release: fix to the header of the ACIS QE contamination file. Prior to this release, CIAO would fail when trying to look up the contamination model correction for chips ACIS-8 (S4) and ACIS-9 (S5).|
|26 Apr 2011||CALDB 4.4.3 release: calibration update - the LETG grating efficiency has been upgraded to vN0007.|
|20 Jul 2011||required software updates are listed in Synopsis|
|10 Jan 2012||reviewed for CIAO 4.4: no changes|
|12 Mar 2012||it isn't necessary to set the fullgarf dtffile parameter for ACIS data, since the DTCOR value is retrieved from the evtfile in this case.|
|03 Dec 2012||Review for CIAO 4.5; no changes|
|24 Apr 2013||Add pointer to new mktgresp tool.|
|10 Dec 2013||Review for CIAO 4.6. Updated for parameter block file parameter deprecation and added note about early observation data.|
|22 Dec 2014||Review for CIAO 4.7. Minor edits only.|
|31 Jan 2022||Review for CIAO 4.14. Added section about repro5 datasets.|