Apply an ACIS Gain Map

Overview

Last Update: 21 May 2007 - need to set stop=none if aspect solution is not provided

Synopsis:

The gainfile is used to compute the ENERGY and PI of an event from the PHA value; see the PI dictionary entry for more information. Each of the values is stored in a column of the same name in the event file. Using the correct gainmap is especially important if one is interested in ENERGY, PI, or the data is for a grating observation. Later in the analysis, the FEF and OSIP files that correspond to the gain map should be used to create an RMF for the data.

Purpose:

To generate a new level=2 event file with the proper gain map applied. If you have already run the Apply the ACIS CTI Correction thread, the newest available gain map has been to the data; it is not necessary to run this thread as well.

Read this thread if:

you are working with any ACIS observation (imaging or grating) that is affected by the Calibration Updates.

Note: if you are working with imaging data, it is important that the calibration applied to the event file is consistent with the RMF tool chosen. Specifically, a different gain file must be used when running acis_process_events; more information is available in the Creating ACIS RMFs why topic. It is recommended that users apply the default gain file to the data, and use mkacisrmf to create the imaging RMF file.

Calibration Updates:

Get Started shows how to check the CALDBVER and temperature of your observation.

• CALDB v3.3.0 (18 Dec 2006): A new set of gain files for -120 data have been added to the CALDB. Only calibration for the BI chips (S1, S3) has changed in this file; calibration for the FI chips is identical to the v5 file. The How CIAO 3.4 and CALDB 3.3.0 Affect Your Analysis section of the CIAO release notes explains how the files will affect your analysis.
• CALDB v3.2.1 (15 Dec 2005): The gain for the back-illuminated (BI) chips - ACIS-S1 and S3 - has been upgraded to match the BI gains from the acisD2000-01-29gain_ctiN0005.fits file. See How CALDB 3.2.1 Affects Your Analysis for details.
• CALDB v3.2.0 (21 Nov 2005): New gain files for -120 data have been added to the CALDB; see the CIAO 3.3 release notes for information on how they will affect your analysis.
• CALDB v3.0.0 (15 Dec 2004): New default gain file (acisD2000-01-29gain_ctiN0003.fits).
• CALDB v2.7 (7 Aug 2001): New gainfiles for analyzing -120 degree observations taken on the S3 chip.
• CALDB v2.2 (15 Feb 2001): All the gainfiles were updated in this release.

Related Links:

• Analysis Guide: ACIS Data Preparation

• Apply the ACIS CTI Correction thread: it is strongly recommended that you reprocess imaging data with this new calibration which became part of standard data processing in DS 6.11. The CTI correction is on by default (apply_cti=yes) in acis_process_events.

• Corrections for time-dependence of ACIS gain: describes the gain change correction algorithm which was derived for the CTI-corrected data in the FI chips and the uncorrected data in S3. This correction will be implemented in acis_process_events in a future release of CIAO; it can be applied now via a C program available from the software exchange page.

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


#--------------------------------------------------------------------------
#
#  acis_process_events.par- Parameter file for acis_process_events program
#
#--------------------------------------------------------------------------
        infile = acisf01838_000N001_evt1.fits  Input event file or stack
       outfile = acis_1838_new_evt1.fits Output event file name
    acaofffile = NONE             aspect offset file ( NONE | none | <filename>)
    (apply_cti = yes)             Apply CTI adjustment?
  (apply_tgain = yes)             Apply time-dependent gain adjustment?
(alignmentfile = )acaofffile -> NONE) sim/fam alignment file ( NONE | none | <filename>)
      (obsfile = NONE)            obs.par file for output file keywords ( NONE | none | <filename>)
      (geompar = geom)            Parameter file for Pixlib Geometry files
      (logfile = stdout)          debug log file ( STDOUT | stdout | <filename>)
    (gradefile = CALDB)           grade mapping file ( NONE | none | CALDB | <filename>)
     (gainfile = CALDB)           acis gain file ( NONE | none | CALDB | <filename>)
   (badpixfile = acis_1838_new_bpix1.fits) acis bad pixel file ( NONE | none | <filename>)
   (threshfile = CALDB)           split threshold file ( NONE | none | CALDB | <filename>)
      (ctifile = CALDB)           acis CTI file ( NONE | none | CALDB | <filename>)
    (tgainfile = CALDB)           gain adjustment file ( NONE | none | CALDB | <filename>)
     (eventdef = )stdlev1 -> {d:time,s:ccd_id,s:node_id,i:expno,s:chip,s:tdet,f:det,f:sky,s:phas,l:pha,l:pha_ro,
f:energy,l:pi,s:fltgrade,s:grade,x:status}) output format definition
   (doevtgrade = yes)             Determine event flight grade?
 (check_vf_pha = no)              Check very faint pixels?
(calc_cc_times = no)              Estimate the times of arrival for CC-mode observation?
        (trail = 0.027)           Trail fraction
     (spthresh = 13)              Default split threshold level (overridden by values in threshfile)
  (time_offset = 0)               Offset to add to event time field to synch w/ fam data
   (docentroid = no)              Determine pixel centroid for coord. conversion?
 (calculate_pi = yes)             perform pha->pi conversion? (requires gain file)
 (pi_bin_width = 14.6)            Width of Pi bin in eV
  (pi_num_bins = 1024)            Number of values to bin energy into
 (max_cti_iter = 15)              Maximum iterations for the CTI adjustment of each event
 (cti_converge = 0.1)             The convergence criterion for each CTI-adjusted pixel in adu
       (tstart = TSTART)          header key containing start/default time value
        (tstop = TSTOP)           header key containing time of last event
      (clobber = no)              Overwrite output event file if it already exists?
      (verbose = 0)               level of debug detail (0=none, 5=most)
         (stop = none)            end transformations at [chip,tdet,det,tan,sky,none]
     (instrume = acis)            axaf instrument- used for instrument parameter file
    (rand_seed = 1)               random seed (for pixlib), 0 = use time dependent seed
     (rand_pha = yes)             Randomize the pha value used in gain calculations
(rand_pix_size = 0.5)             pixel randomization width (-size..+size) 0=no randomization
      (stdlev1 = {d:time,s:ccd_id,s:node_id,i:expno,s:chip,s:tdet,f:det,f:sky,s:phas,l:pha,l:pha_ro,f:energy,
l:pi,s:fltgrade,s:grade,x:status}) TE faint modes event definition string
      (grdlev1 = {d:time,s:ccd_id,s:node_id,i:expno,s:chip,s:tdet,f:det,f:sky,l:pha,l:pha_ro,s:corn_pha,f:energy,
l:pi,s:fltgrade,s:grade,x:status}) TE graded event format definition string
       (cclev1 = {d:time,s:ccd_id,s:node_id,i:expno,s:chip,s:tdet,f:det,f:sky,f:sky_1d,s:phas,l:pha,l:pha_ro,
f:energy,l:pi,s:fltgrade,s:grade,x:status}) CC faint event format definition string
    (ccgrdlev1 = {d:time,s:ccd_id,s:node_id,i:expno,s:chip,s:tdet,f:det,f:sky,f:sky_1d,l:pha,l:pha_ro,s:corn_pha,
f:energy,l:pi,s:fltgrade,s:grade,x:status}) cc graded event format definition string
         (mode = ql)