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Last modified: 15 Mar 2010
Where are the PDFs?

LETG/HRC-S Grating Spectra

CIAO 4.2 Science Threads



Overview

Last Update: 15 Mar 2010 - added link to the Computing Average HRC Dead Time Corrections thread (S-Lang or Python) in the Summary

Synopsis:

Generate a new PHA2 spectrum file for any LETG/HRCS-S grating observation to ensure that consistent calibration is used throughout the analysis.

Read this thread if:

you are working with an HRC-S/LETG dataset and want to create a new level=2 event file and extract a Type II PHA grating spectrum file.

A new HRC-S gain map and pulse-height filter were released in CALDB 4.2.0 (December 2009). The new calibration files must be applied to the data as a pair: to use the new PI filter, the dataset has to be reprocessed with the new gain map.

These calibrations updates were added to SDP at version DS 8.3. Get Started shows how to check the software version used in processing your data.

Calibration Updates:

Related Links:




Contents



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.



Data Preparation

This analysis thread starts with the level 1 event file. Before beginning, users may wish to reprocess the data to create a new event file with the most recent calibration applied. Instructions on how to reprocess your data are available in the HRC Data Preparation Analysis Guide.



Get Started

Sample ObsID used: 460 (LETG/HRC-S, 3C 273)

File types needed: evt1; flt1; asol1

In this thread, we assume that all relevant files are in the same working directory.

To find the software version that was used on the data, check the ASCDSVER keyword in the header:

unix% dmkeypar hrcf00460_000N004_evt1.fits ASCDSVER echo+
6.5.1

Since these data have an ASCDSVER lower than DS 8.3, the new gain file and PI filter have not been applied. The new calibration files must be applied to the data as a pair: to use the new PI filter in this thread, first the dataset has to be reprocessed with the new gain map.

If you do not need to run this thread, go directly to the HRC Grating RMFs thread.



Generate a New Level=1.5 Event File

1. Get position of zero-order image (tgdetect)

To find the zero-order location, the tool tgdetect is run:

unix% punlearn tgdetect
unix% pset tgdetect infile=hrcf00460_000N004_evt1.fits
unix% pset tgdetect outfile=hrc_460_evt1_src1a.fits
unix% tgdetect
Input L1 event file  (hrcf00460_000N004_evt1.fits): 
Input source position(s) file from previous OBI or NONE (NONE): 
Output source position(s) file name (hrc_460_evt1_src1a.fits): 

# DMCOPY (CIAO 4.2): Bad data type in filter string formatting

The warning may be ignored; it is due to a minor bug in the Data Model and does not affect the output of tgdetect.

The contents of the parameter file may be checked using plist tgdetect.

The source list may be viewed over the event file using ds9:

unix% ds9 hrcf00460_000N004_evt1.fits &

Overlay the source list: Region → Load Regions → hrc_460_evt1_src1a.fits.

If the zero order of the source is outside of the default search area (e.g. far from the aimpoint), tgdetect will not find it. If this problem affects your data, it will be obvious when the source list is displayed on the event file. In this case, run the Correcting a Misplaced Zero-order Source Position thread to identify the correct source position.


2. Get region mask (tg_create_mask)

The location of the spectrum needs to be found next, via the tool tg_create_mask.

unix% punlearn tg_create_mask
unix% pset tg_create_mask infile=hrcf00460_000N004_evt1.fits
unix% pset tg_create_mask outfile=hrc_460_evt1_L1a.fits
unix% pset tg_create_mask input_pos_tab=hrc_460_evt1_src1a.fits
unix% tg_create_mask
Input event file or stack (hrcf00460_000N004_evt1.fits): 
Output region file or stack (hrc_460_evt1_L1a.fits): 
Input table with zero order positions or stack (hrc_460_evt1_src1a.fits): 
Observed grating type (header_value|HETG|HEG|MEG|LETG) (HETG|HEG|MEG|LETG|header_value|HEADER_VALUE) (header_value): 

The region file, hrc_460_evt1_L1a.fits, will be used to mask the event file. The regions may be viewed over the event file using ds9:

unix% ds9 hrcf00460_000N004_evt1.fits &

Overlay the region file: Region → Load Regions → hrc_460_evt1_L1a.fits. Figure 1 shows the regions on the event file .

The contents of the parameter file may be checked using plist tg_create_mask.

[Thumbnail image: The region mask outlines the photons from the source and the grating arms.]

[Version: full-size]

[Print media version: The region mask outlines the photons from the source and the grating arms.]

Figure 1: Event file with region file overlaid

The regions are loaded from the L1a.fits file, which was made by tg_create_mask.


3. Run tg_resolve_events

The tool tg_resolve_events is now used to assign grating events to spectral orders:

unix% punlearn tg_resolve_events
unix% pset tg_resolve_events infile=hrcf00460_000N004_evt1.fits
unix% pset tg_resolve_events outfile=hrc_460_evt1a.fits
unix% pset tg_resolve_events regionfile=hrc_460_evt1_L1a.fits
unix% pset tg_resolve_events acaofffile=@pcad_asol1.lis
unix% pset tg_resolve_events eventdef=")stdlev1_HRC"
unix% pset tg_resolve_events osipfile=none
unix% tg_resolve_events
Input event file or stack (hrcf00460_000N004_evt1.fits): 
Input region file or stack (hrc_460_evt1_L1a.fits): 
Output event file or stack (hrc_460_evt1a.fits): 
Input aspect offset file (@pcad_asol1.lis): 

It is important to note several things here:

  • In many cases, there will be more than one aspect solution file (pcad_asol1.fits) for an observation. All the files must be input to the acaofffile parameter in chronological order (the time is in the filename, so "ls" lists them in order), either as a comma-separated list or as a stack. Here we use:

    unix% cat pcad_asol1.lis
    pcadf063792009N003_asol1.fits
    
  • The unusual syntax of the eventdef parameter; the tool will not access the predefined string if the leading ")" is missing.

The contents of the parameter file may be checked using plist tg_resolve_events.



Generate a New Level=2 Event File

1. Apply background filter (dmcopy)

A new pulse-height filter for use with LETG data was released in CALDB 4.2.0 (15 December 2009). Over half of Level=2 background events can be removed at most wavelengths with a loss of ~1.25% of X-ray events. This is the recommended filter for use with all HRC-S/LETG data.

The LETG/HRC-S Background Filter page has detailed information on how this filter was developed.

unix% punlearn dmcopy
unix% dmcopy \
      "hrc_460_evt1a.fits[EVENTS][(tg_mlam,pi)=region($CALDB/data/chandra/hrc/tgpimask2/letgD1999-07-22pireg_tgmap_N0001.fits)]" \
      hrc_460_back_evt1a.fits opt=all

2. Filter on status (dmcopy)

We need to apply the status filter that is specific to HRC-S observations; a value of 0 demands that the bit be flagged as "good", a value of x indicates that either status (0/1) is acceptable:

unix% punlearn dmcopy
unix% dmcopy "hrc_460_back_evt1a.fits[status=xxxxxx00xxxx0xxx0000x000x00000xx]" \
      hrc_460_flt1_evt1a.fits opt=all

3. Apply GTI filter (dmcopy)

The Good Time Intervals (GTIs) supplied by the pipeline now need to be applied:

unix% punlearn dmcopy
unix% dmcopy \
      "hrc_460_flt1_evt1a.fits[EVENTS][@hrcf00460_000N004_std_flt1.fits]" \
      hrc_460_evt2.fits opt=all

Be sure to include the @ symbol in the filter expression; the command will not be executed properly if it is omitted.


4. Spatial filtering (dmcopy, optional)

Electrical field-fringing effects on the ends of the three HRC-S segments create high background emission. The bad pixel map doesn't cut off all of this high-background region, and users may wish to apply additional spatial filtering with dmcopy, such as:

rawy=:16383,17070:32200,32980:

In any case, spectral features near the plate gaps should be treated with suspicion.



Extract a Grating Spectrum (tgextract)

The CIAO tool tgextract produces a PHA2 spectrum file from the level=2 data file:

unix% punlearn tgextract
unix% pset tgextract infile=hrc_460_evt2.fits
unix% pset tgextract outfile=hrc_460_pha2.fits
unix% pset tgextract inregion_file=CALDB
unix% tgextract
Input event file (output event file from L1.5 processing) (hrc_460_evt2.fits): 
If typeII, enter full output file name or '.'; if typeI, enter output rootname (hrc_460_pha2.fits): 
Input ancillary response file name (none): 
Input redistribution file name (none): 
Source ID's to process: 'all', comma list, @file (all): 
Grating parts to process: HETG, HEG, MEG, LETG, header_value (HETG|HEG|MEG|LETG|header_value) (header_value): 
Grating diffraction orders to process: 'default', comma list, range list, @file (default): 
Ouput file type: typeI (single spectrum) or typeII (multiple spectra) (pha_typeI|pha_typeII) (pha_typeII): 

The inregion_file needs to be set to "CALDB" (instead of the default value "NONE") so that the special bow-tie extraction region used with HRC-S/LETG observations is picked up.

The contents of the parameter file may be checked using plist tgextract.




Summary

This thread is now complete; the PHA2 grating spectrum file is named hrc_460_pha2.fits. You should next:

  1. read the Computing Average HRC Dead Time Corrections thread (S-Lang or Python) to see if you need to recompute the deadtime statistics for your dataset
  2. create HRC Grating RMFs

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/tgdetect.par


##
## TGDETECT -- Create filter; run celldetect; narrow down detected
##             'zero order' source list; set source id's; match 
##             sources to previous OBI source list.
##
## Note: if either "infile" or "OBI_srclist_file" are @lists, only
## the first item on the list is read in;  this tool only works on
## one set of input files;  if more than one file is listed, 
## everything but the first are ignored.
##
        infile = hrcf00460_000N004_evt1.fits    Input L1 event file
OBI_srclist_file = NONE             Input source position(s) file from previous OBI or NONE
       outfile = hrc_460_evt1_src1a.fits Output source position(s) file name
#
#   output file naming
#
     (temproot = )                Path and root file name to be given to temporary files
     (keeptemp = no)              Keep temporary files?
     (keepexit = no)              Keep exit status file?
#
#
#
     (zo_pos_x = default)         Center GZO filter sky X position (default=pixel(ra_nom))
     (zo_pos_y = default)         Center GZO filter sky Y position (default=pixel(dec_nom))
 (zo_sz_filt_x = default)         Size of GZO filter in X pixels (ACIS=400; HRC=1800)
 (zo_sz_filt_y = default)         Size of GZO filter in Y pixels (ACIS=400; HRC=1800)
   (snr_thresh = 40)              SNR threshold to select the detected sources
# 
#   celldetect parameters
#
       (expstk = none)            list of exposure map files
       (thresh = )celldetect.thresh -> 3) celldetect source threshold
     (ellsigma = 3.0)             Size of output source ellipses (in sigmas)
     (expratio = 0)               cutoff ratio for source cell exposure variation
    (findpeaks = yes)             find local peaks for celldetect
(celldetect_log = )celldetect.log -> no) make a celldetect log file?
     (psftable = )celldetect.psftable -> /soft/ciao/data/psfsize20010416.fits) table of PSF size data, for celldetect
    (fixedcell = 15)              celldetect fixed cell size to use
(fixedcell_cc_mode = 15)              celldetect fixed cell size to use for CC mode ACIS data
      (bkgfile = none)            background file, for celldetect
     (bkgvalue = )celldetect.bkgvalue -> 0) background count/pixel, for celldetect
  (bkgerrvalue = )celldetect.bkgerrvalue -> 0) background error, for celldetect
        (eband = )celldetect.eband -> 1.4967) energy band, for celldetect
      (eenergy = )celldetect.eenergy -> 0.8) encircled energy of PSF, for celldetect
      (snrfile = none)            celldetect snr output file (for convolution only)
     (convolve = )celldetect.convolve -> no) use convolutions for celldetect
      (xoffset = INDEF)           celldetect offset of x axis from optical axis
      (yoffset = INDEF)           celldetect offset of y axis from optical axis
     (cellfile = none)            output cell size image file
     (centroid = yes)             compute source centroids in celldetection?
#
#   tgidselectsrc parameters
#
(snr_ratio_limit = )tgidselectsrc.snr_ratio_limit -> 1) Value of SNR ratio to use as lower limit
     (setsrcid = )tgidselectsrc.setsrcid -> yes) Set src ids in output file?
#
#   tgmatchsrc parameters
#
(max_separation = )tgmatchsrc.max_separation -> 3) Maximum allowed separation (arcsec) for sources to match
#
#
      (clobber = no)              OK to overwrite existing output file(s)?
      (verbose = 0)               Verbosity level (0 = no display)
         (mode = ql)              




Parameters for /home/username/cxcds_param/tg_create_mask.par


##
## TG_CREATE_MASK -- Calculates the mask regions of the grating arms
##    for AXAF flight L1 grating data files.  The output is a region
##    file(s) in sky coordinates.
##
        infile = hrcf00460_000N004_evt1.fits    Input event file or stack
       outfile = hrc_460_evt1_L1a.fits Output region file or stack
 input_pos_tab = hrc_460_evt1_src1a.fits Input table with zero order positions or stack
   grating_obs = header_value     Observed grating type (header_value|HETG|HEG|MEG|LETG)
     sA_zero_x = 1                Source A - x position of zero order
     sA_zero_y = 1                Source A - y position of zero order
     sB_zero_x = 1                Source B - x position of zero order
     sB_zero_y = 1                Source B - y position of zero order
     sC_zero_x = 1                Source C - x position of zero order
     sC_zero_y = 1                Source C - y position of zero order
     sD_zero_x = 1                Source D - x position of zero order
     sD_zero_y = 1                Source D - y position of zero order
     sE_zero_x = 1                Source E - x position of zero order
     sE_zero_y = 1                Source E - y position of zero order
     sF_zero_x = 1                Source F - x position of zero order
     sF_zero_y = 1                Source F - y position of zero order
     sG_zero_x = 1                Source G - x position of zero order
     sG_zero_y = 1                Source G - y position of zero order
     sH_zero_x = 1                Source H - x position of zero order
     sH_zero_y = 1                Source H - y position of zero order
     sI_zero_x = 1                Source I - x position of zero order
     sI_zero_y = 1                Source I - y position of zero order
     sJ_zero_x = 1                Source J - x position of zero order
     sJ_zero_y = 1                Source J - y position of zero order
(input_psf_tab = CALDB)           Calibration file with mirror psf vs off-axis angle
     (detector = header_value)    Detector type: ACIS | HRC-I | HRC-S | header_value
(radius_factor_zero = 50)              A scale factor which multiplies the app. calculation of the one-sigma
(width_factor_hetg = 35)              A scale factor which multiplies the one-sigma width of the heg/meg mask
(width_factor_letg = 40)              A scale factor which multiplies the one-sigma width of the letg mask
(r_astig_max_hetg = 0.5600000000000001) Max grating r coord (deg, along the dispersion) for HETG astigmatism
(r_astig_max_letg = 1.1)             Max grating r coord (deg, along the dispersion) for LETG astigmatism calc
(r_mask_max_hetg = 0.992)           Max grating r coord (deg) for HETG mask (to support offset pointing)
(r_mask_max_letg = 2.1)             Max grating r coordinate (deg) for LETG mask (to support offset pointing)
# --------------------------------------------------------------------------
# The parameters below are to be set ONLY if the user wants to use their
# own grating mask sizes instead of having the masks automatically generated.
# Only ONE input file, with up to 10 soures, can be processed using the user 
# params.  @ lists of multiple files can only be done with automated mask
# processing, or by running each file individually with hand set mask sizes.
# To start, you MUST set the following parameters:
#
# > pset tg_create_mask use_user_pars=yes last_source_toread=[letter A -> J]
#
# The parameter last_source_toread should be set to the last source letter
# for which you will enter parameters.  If you want to input 2 sources 
# (regardless of their source id's), the last_source_toread=B. Sections
# A -> J are for (upto) 10 user specified sources.  In each sections, 
# each source must have an ID, a zero order center position specified, 
# as well as the grating mask width(s).  An example with 2 HETG sources, 
# with src_id's 6 and 3:
#
# > pset tg_create_mask use_user_pars=yes last_source_toread=B
# > pset tg_create_mask sA_id=6 sA_zero_x=4762.34 sA_zero_y=2344.29 
# > pset tg_create_mask sA_zero_rad=35 sA_width_heg=25 sA_width_meg=28
# > pset tg_create_mask sB_id=3 sB_zero_x=4063.54 sB_zero_y=6346.62 
# > pset tg_create_mask sB_zero_rad=45 sB_width_heg=50 sB_width_meg=75
#              (units are all in sky pixels)
#
# NOTE: for Continuous Clocking data (CC mode), the HETG mask does not
# require the s#_width_heg, since the meg mask will encompase the entire
# data set.  HEG event processing in CC mode is done using the next 
# tool tg_resolve_events.
# --------------------------------------------------------------------------
(use_user_pars = no)              Use the user defined mask parameters below: yes or no?
(last_source_toread = A)               Last source name to be read; character A->J.
# --------------------------------------------------------------------------
# 			Source A parameters
# --------------------------------------------------------------------------
        (sA_id = 1)               Source A - source id number
  (sA_zero_rad = )                Source A - radius of zero order mask
 (sA_width_heg = )                Source A - width of heg mask in sky pixels
 (sA_width_meg = )                Source A - width of meg mask in sky pixels
 (sA_width_leg = )                Source A - width of leg mask in sky pixels
# --------------------------------------------------------------------------
#                       Source B parameters
# --------------------------------------------------------------------------
..(through Source J)..
      (geompar = geom)            Parameter file for Pixlib Geometry files
      (verbose = 0)               Verbose level: 0 - no output, 5 - max verbosity
      (clobber = no)              Clobber existing outfile?
         (mode = ql)              




Parameters for /home/username/cxcds_param/tg_resolve_events.par


#--------------------------------------------------------------------------
#
#   tg_resolve_events.par: Parameter file for the tg_resolve_events program
#
#--------------------------------------------------------------------------
        infile = hrcf00460_000N004_evt1.fits    Input event file or stack
       outfile = hrc_460_evt1a.fits   Output event file or stack
    regionfile = hrc_460_evt1_L1a.fits Input region file or stack
    acaofffile = @pcad_asol1.lis  Input aspect offset file
(alignmentfile = )acaofffile -> @pcad_asol1.lis) Input sim offset file
      (logfile = stdout)          Output log (NONE|<filename>|stdout)
# The osipfile contains position dependent energy limits based on
# the CCD resolution, used for order-sorting.
# A value of "NONE" means that the file will not be used, and
# that the parameters, osort_hi and osort_lo will be used.
     (osipfile = none)            Lookup table for order resolving (for acis data only)
#sort_hi, osort_lo specify fractional deviations from the integer
#order which will be included in order-sorting via CCD ENERGY values (PHA).
#eg. osort_lo-0.3, osort_hi=0.2 means that photons with real-valued
#orders between 0.7 < order <= 1.2 will be included in first order,
#1.7 < order <= 2.2 will be second order, etc.
     (osort_lo = 0.3)             Order-sorting lower bound fraction; order > m - osort_lo
     (osort_hi = 0.3)             Order-sorting high bound fraction; order <= m + osort_hi
  (grating_obs = header_value)    Observed grating type (header_value|HETG|HEG|MEG|LETG)
     (detector = header_value)    Detector type: ACIS | HRC-I | HRC-S | header_value
(energy_lo_adj = 1.0)             Lower Energy limit factor
(energy_hi_adj = 1.0)             Upper Energy limit factor
  (time_offset = 0)               Offset to add to event time to synch w/ alignment data
    (rand_seed = 1)               Random seed (for pixlib), 0 = use time dependent seed
(rand_pix_size = 0.0)             pixel randomization width (-size..+size), 0.0 = no randomization
     (eventdef = )stdlev1_HRC -> {d:time,f:rd,s:chip,l:tdet,f:det,f:sky,s:chip_id,s:pha,s:pi,s:tg_m,
f:tg_lam,f:tg_mlam,s:tg_srcid,s:tg_part,s:tg_smap,x:status}) Output format definition
      (stdlev1 = )eventdef -> {d:time,f:rd,s:chip,l:tdet,f:det,f:sky,s:chip_id,s:pha,s:pi,s:tg_m,
f:tg_lam,f:tg_mlam,s:tg_srcid,s:tg_part,s:tg_smap,x:status}) 
 (stdlev1_ACIS = {d:time,i:expno,f:rd,s:chip,s:tdet,f:det,f:sky,s:ccd_id,l:pha,s:pi,f:energy,s:grade,
s:fltgrade,s:node_id,s:tg_m,f:tg_lam,f:tg_mlam,s:tg_srcid,s:tg_part,s:tg_smap,x:status})
ACIS event format definition string
  (stdlev1_HRC = {d:time,f:rd,s:chip,l:tdet,f:det,f:sky,s:chip_id,s:pha,s:pi,s:tg_m,f:tg_lam,f:tg_mlam,
s:tg_srcid,s:tg_part,s:tg_smap,x:status}) HRC event format definition string
# --------------------------------------------------------------------------
      (geompar = geom)            Parameter file for Pixlib Geometry files
      (verbose = 0)               Verbosity level of detail (0=none, 5=most)
      (clobber = no)              Clobber outfile if it already exists?
         (mode = ql)              




Parameters for /home/username/cxcds_param/tgextract.par


##
## TGEXTRACT -- create 1D spectrum(a) table file(s) from the
##              L1.5 output event list
##
        infile = hrc_460_evt2.fits    Input event file (output event file from L1.5 processing)
       outfile = hrc_460_pha2.fits    If typeII, enter full output file name or '.'; if typeI, enter output rootname
#
# tg_srcid_list parameter explanation...
#  - "all" will process all the sources id's found in the event list
#  - a comma list is a comma separated string list of all the 
#    sources to process, ie:
#       "1,2,5,7"
#  - @file is a pointer to an ascii file which contains a comma
#    separated list of the id's to process
#
 tg_srcid_list = all              Source ID's to process: 'all', comma list, @file
  tg_part_list = header_value     Grating parts to process: HETG, HEG, MEG, LETG, header_value
#
# tg_order_list parameter explanation...
#  - "default" is set to process the following:
#       if ACIS:  1, 2, 3, -1, -2, -3
#       if HRC:   -1, 1
#  - a comma list is a comma separated string list of the orders
#    the user wants to process, ie:
#       "-5, -1, 1, 3"
#  - a range list sets the min and max of the orders to process;
#    all the orders in between, will be processed, ie:
#       "-1..5"  will do orders from -1 to +5th order
#    a range list can be mixed with comma separated list
#  - @file is a pointer to an ascii file which contains a comma
#    separated list and/or range list of the orders to process
#
 tg_order_list = default          Grating diffraction orders to process: 'default', comma list, range list, @file
      ancrfile = none             Input ancillary response file name
      respfile = none             Input redistribution file name
  outfile_type = pha_typeII       Ouput file type: typeI (single spectrum) or typeII (multiple spectra)
(inregion_file = CALDB)           Input region file.
     (backfile = none)            Input background file name
        (rowid = )                If rowid column is to be filled in, enter name here
    (bin_units = angstrom)        Bin units (for bin parameters below): angstrom, eV, keV
  (min_bin_leg = compute)         Minimum dispersion coordinate for LEG, or 'compute'
  (max_bin_leg = compute)         Maximum dispersion coordinate for LEG, or 'compute' 
 (bin_size_leg = compute)         Bin size for binning LEG spectra, or 'compute'
 (num_bins_leg = compute)         Number of bins for the output LEG spectra, 'compute'
  (min_bin_meg = compute)         Minimum dispersion coordinate for MEG, or 'compute'
  (max_bin_meg = compute)         Maximum dispersion coordinate for MEG, or 'compute'
 (bin_size_meg = compute)         Bin size for binning MEG spectra, or 'compute'
 (num_bins_meg = compute)         Number of bins for the output MEG spectra, or 'compute'
  (min_bin_heg = compute)         Minimum dispersion coordinate for HEG, or 'compute'
  (max_bin_heg = compute)         Maximum dispersion coordinate for HEG, or 'compute'
 (bin_size_heg = compute)         Bin size for binning HEG spectra, or 'compute'
 (num_bins_heg = compute)         Number of bins for the output HEG spectra, 'compute'
     (min_tg_d = default)         Minimum tg_d range to include in histogram, or use 'default'
     (max_tg_d = default)         Maximum tg_d range to include in histogram, or use 'default'
(extract_background = yes)             Extract the local background spectrum?
(min_upbkg_tg_d = default)         Minimum value of tg_d for the background up spectrum.
(max_upbkg_tg_d = default)         Maximum value of tg_d for the background up spectrum.
(min_downbkg_tg_d = default)         Minimum value of tg_d for the background down spectrum.
(max_downbkg_tg_d = default)         Maximum value of tg_d for the background down spectrum.
      (geompar = geom)            Parameter file for Pixlib Geometry files
      (clobber = no)              OK to overwrite existing output file(s)?
      (verbose = 0)               Verbosity level (0 = no display)
         (mode = ql)              



History

16 Dec 2004 updated for CIAO 3.2: minor changes to parameter files
15 Feb 2005 new filtering bug discovered, follow workaround in Apply the background filter section
15 Jun 2005 updated for DS 7.6: the bow-tie region from the CALDB is used by default in tgextract (as shown in the Extract a Grating Spectrum section)
05 Dec 2005 updated for CIAO 3.3: bug fixes to the Data Model make the workaround previously given in the Apply the background filter section unnecessary (i.e. the modpireg script); output filenames include ObsID; parameter file change (kernel parameter removed from all "tg" tools)
05 Jan 2006 created Data Preparation section
01 Dec 2006 updated for CIAO 3.4: change to wording of tgdetect/dmcopy warning
11 Jan 2008 updated for CIAO 4.0: ds9 now automatically looks for the "[REGION]" or "[SRCLIST]" extension in the region file, so it doesn't have to be specified; check if data have gone through Reprocessing III
25 Nov 2008 added "ADDSPI and SPIFILTER" link in Generate a New Level=2 Event File section
21 Jan 2009 updated for CIAO 4.1: image converted to inline; path to HRC-S background filter file is different in CALDB 4.1
19 Feb 2009 added grouping information to the Summary
16 Jun 2009 added About the Chandra Grating Data Archive and Catalog section
22 Dec 2009 updated for CIAO 4.2: new HRC-S TGAIN and LETG PI filter released in CALDB 4.2.0
28 Dec 2009 additional updates for CIAO 4.2: "pha=0:254" filter is obsolete; the background filter is applied to "(tg_mlam,pi)" [prior to CIAO 4.2, was "(tg_lam,pi)"]; added an optional spatial filtering section
18 Feb 2010 the new gain filter and PI filter are applied in standard data processing as of version DS 8.3
15 Mar 2010 added link to the Computing Average HRC Dead Time Corrections thread (S-Lang or Python) in the Summary

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Where are the PDFs?
Last modified: 15 Mar 2010