Chandra X-Ray Observatory
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Last modified: 10 July 2017

URL: http://cxc.harvard.edu/ciao/threads/spectra_hetgacis/

HETG/ACIS-S Grating Spectra

CIAO 4.9 Science Threads


Overview

Synopsis:

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

Run this thread if:

You are working with an ACIS/HETG dataset taken in TIMED mode and want to create a new level=2 event file and extract a Type II PHA grating spectrum file.

For data taken with ACIS/HETG taken in CONTINUOUS clocking (CC) mode, please follow the HETG/ACIS-S/CC-Mode Grating Spectra thread.

Related Links:

Last Update: 10 Jul 2017 - Added link to new analysis of ACIS+HETG background rates.


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.


About the chandra_repro script

The chandra_repro script reprocessing script automates the recommended data processing steps presented in the CIAO analysis threads. The script reads data from the standard data distribution (e.g. primary and secondary directories) and creates a new bad pixel file, a new level=2 event file, and a new level=2 Type II PHA file.

chandra_repro also will now create the appropriate ARF and RMF for each grating order and arm in the spectrum using the mktgresp script. The response files will be stored in a tg/ subdirectory of the outdir parameter.

Refer to "ahelp chandra_repro" for more information.

[WARNING]
Running chandra_repro?

If you have run chandra_repro you do not need to complete the rest of this thread unless you want to understand the individual processing steps, the options avaiable, or need to apply any non-standard calibrations.


Data Preparation

This analysis thread starts with the level 1 event file. Before beginning, users may wish to reprocess the data with chandra_repro to create a new event file with the most recent calibration applied.

It is also suggested that users set the observation-specific bad pixel file, as described in the Setting the Observation-specific Bad Pixel Files thread.


Get Started

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

unix% download_chandra_obsid 459 evt1,flt,asol

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

[NOTE]
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.

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


Generate a New Level=1.5 Event File

1. Get position of zero-order image (tgdetect2)

To find the zero-order location, the tool tgdetect2 is run. tgdetect2 will automatically select the best tool: tgdetect or tg_findzo.

unix% punlearn tgdetect2
unix% pset tgdetect2 infile=acisf00459_000N003_evt1.fits
unix% pset tgdetect2 outfile=acis_459_src1a.fits
unix% tgdetect2
Input event file (acisf00459_000N003_evt1.fits): 
Output source table file (acis_459_src1a.fits): 

The contents of the parameter file may be checked using plist tgdetect2.

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

unix% ds9 acisf00459_000N003_evt1.fits &

Overlay the source list: Region → Load Regions → acis_459_src1a.fits.

tgdetect2 will try to find the best method possible to determine the correct zeroth order location. However, there may be exceptional cases where the results are incorrect. Displaying the region in ds9 will identify such exceptional cases.

Users working in crowded fields or with extended objects may find tgdetect2 has strayed from the intended source. These users should manually set the tg_create_mask source parameters as described in the Correcting a Misplaced Zero-order Source Position thread.


2. Get region mask (tg_create_mask)

The location of the HEG and MEG "arms" needs to be found next, via the tool tg_create_mask.

unix% punlearn tg_create_mask
unix% pset tg_create_mask infile=acisf00459_000N003_evt1.fits
unix% pset tg_create_mask outfile=acis_459_evt1_L1a.fits
unix% pset tg_create_mask input_pos_tab=acis_459_src1a.fits
unix% tg_create_mask
Input event file or stack (acisf00459_000N003_evt1.fits): 
Output region file or stack (acis_459_evt1_L1a.fits): 
Input table with zero order positions or stack (acis_459_src1a.fits): 
Observed grating type (header_value|HETG|HEG|MEG|LETG) (HETG|HEG|MEG|LETG|header_value|HEADER_VALUE) (header_value): 

The region file, acis_459_evt1_L1a.fits, will be used to mask the event file. The regions may be viewed over the event file using ds9:

unix% ds9 acisf00459_000N003_evt1.fits &

Overlay the region file: Region → Load Regions → acis_459_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, using the detector energy resolution for order separation:

unix% punlearn tg_resolve_events
unix% pset tg_resolve_events infile=acisf00459_000N003_evt1.fits
unix% pset tg_resolve_events outfile=acis_459_evt1a.fits
unix% pset tg_resolve_events regionfile=acis_459_evt1_L1a.fits
unix% pset tg_resolve_events acaofffile=@pcad_asol1.lis
unix% tg_resolve_events
Input event file or stack (acisf00459_000N003_evt1.fits):
Input region file or stack (acis_459_evt1_L1a.fits):
Output event file or stack (acis_459_evt1a.fits):
Input aspect offset file (@pcad_asol1.lis):

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 
pcadf063874624N003_asol1.fits

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


Generate a New Level=2 Event File

1. Apply grade/status filters (dmcopy)

Filter for bad grades and for a "clean" status column (i.e. all bits set to 0):

unix% punlearn dmcopy
unix% dmcopy "acis_459_evt1a.fits[EVENTS][grade=0,2,3,4,6,status=0]" \
      acis_459_flt1_evt1a.fits opt=all

2. Apply GTI filters (dmcopy)

The Good Time Intervals (GTIs) supplied by the pipeline now need to be applied. We simultaneously eliminate an unnecessary column from the output:

unix% punlearn dmcopy
unix% dmcopy \
      "acis_459_flt1_evt1a.fits[EVENTS][@acisf00459_000N003_flt1.fits][cols -phas]" \
      acis_459_evt2.fits opt="" 

unix% dmappend \
      "acis_459_flt1_evt1a.fits[region][subspace -time]" \
      acis_459_evt2.fits

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

The opt="" parameter in dmcopy and the dmappend command are a workaround for the bug in time-filtering grating data.

There are a few observations where ACIS begins to collect event data before the aspect solution is available. Under some rare circumstances these events are not removed by the GTI filter which results in the first few events in the Level 2 event file to contain invalid sky coords (beyond the 1 to 8192 range). These events can be removed with the following dmcopy command:

unix% dmcopy "acis_repro_evt2.fits[EVENTS][x=:,y=:]" acis_filter_xy_repro_evt2.fits

Users do not generally need to worry about these invalid event unless they are merging observations.

Users at this stage may wish to apply other filters via additional dmcopy calls. For example, this would be the appropriate point to apply a time filter to the data.


Extract a Grating Spectrum (tgextract)

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

unix% punlearn tgextract
unix% pset tgextract infile=acis_459_evt2.fits
unix% pset tgextract outfile=acis_459_pha2.fits
unix% tgextract
Input event file (output event file from L1.5 processing) (acis_459_dstrk_evt2.fits): 
If typeII, enter full output file name or '.'; if typeI, enter output rootname (acis_459_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 contents of the parameter file may be checked using plist tgextract.


Summary

This thread is complete; the PHA2 grating spectrum file is named acis_459_pha2.fits. You should now proceed to the ACIS-S Grating RMFs thread.

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/tgdetect2.par


        infile = acisf00459_000N003_evt1.fits Input event file
       outfile = acis_459_src1a.fits Output source table file
     (zo_pos_x = default)         Initial guess for sky-x position (default=pixel(ra_targ))
     (zo_pos_y = default)         Initial guess for sky-y position (default=pixel(dec_targ))
(unlearn_tgdetect = yes)             yes = punlearn tgdetect to set all its parameters to defaults
(unlearn_tg_findzo = yes)             yes = punlearn tg_findzo to set all its parameters to defaults
     (temproot = )                Path and root file name to be given to temporary files
     (keepexit = no)              Keep exit status file?
      (clobber = no)              OK to overwrite existing output file?
      (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 = acisf00459_000N003_evt1.fits   Input event file or stack
       outfile = acis_459_evt1_L1a.fits Output region file or stack
 input_pos_tab = acis_459_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 mas
(width_factor_letg = 40)              A scale factor which multiplies the one-sigma width of the letg mask i
(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 = acisf00459_000N003_evt1.fits   Input event file or stack
       outfile = acis_459_evt1a.fits  Output event file or stack
    regionfile = acis_459_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 = CALDB)           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_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})
Output format definition
      (stdlev1 = )eventdef ->{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})
 (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 = acis_459_evt2.fits Input event file (output event file from L1.5 processing)
       outfile = acis_459_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 = none)            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
14 Jan 2005 created the Data Preparation section
05 Dec 2005 updated for CIAO 3.3: output filenames include ObsID; parameter file changes (kernel parameter removed from all "tg" tools; several changes to the destreak parameter file, including a new default value for the mask parameter)
05 Jan 2006 information on reprocessing included in Data Preparation section
04 Apr 2006 expanded information on special cases in the Get position of zero-order image (tgdetect) section
18 Dec 2006 updated for CIAO 3.4: new calibration files in CALDB 3.3.0; 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; removed outdated calibration updates; check if data have gone through Reprocessing III
21 Jan 2009 updated for CIAO 4.1: image converted to inline; tg_resolve_events no longer prints the "dsTREUNKNOWNINCOLERR -- WARNING: Not loading data from unrecognized level 1.5 input column." message, as it does not affect data analysis; input data must have a CTI_APP keyword
19 Feb 2009 added grouping information to the Summary
13 Mar 2009 added more information to the Data Preparation section; note on other filtering added to end of Generate a New Level=2 Event File section; note added to to run destreak section that this step may be considered optional for gratings
16 Jun 2009 added About the Chandra Grating Data Archive and Catalog section
14 Jan 2009 updated for CIAO 4.2: ObsID 459 file versions
12 Jan 2011 reviewed for CIAO 4.3: no changes
25 Feb 2011 the 25 Feb release of the chandra_repro reprocessing script supports data processing for ACIS and HRC grating data
25 Mar 2011 added workaround for GTI filtering bug to the Apply GTI filter section
06 Jan 2012 reviewed for CIAO 4.4: the destreak tool is now run in the reprocessing thread
03 Dec 2012 Review for CIAO 4.5; added pointer to tg_findzo thread
14 Jan 2013 Removed link to repro-3
24 Apr 2013 Updated the chandra_repro section to make it clear the it does all the steps in this thread and that responses are now also created.
11 Dec 2013 Reviewd for CIAO 4.6; Updated for tgdetect2
22 Dec 2014 Reviewed for CIAO 4.7; no changes.
13 Apr 2015 Added a note about optional extra dmcopy command to remove rare instance invalid sky coordinates.
10 Dec 2015 Updated to indicate this this thread is for TIMED mode observations only. Data taken in CC mode should follow the HETG/ACIS-S/CC-Mode Grating Spectra thread.
10 Jul 2017 Added link to new analysis of ACIS+HETG background rates.


Last modified: 10 July 2017
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