Use Observation-specific Bad Pixel Files
[CIAO 3.4 Science Threads]
OverviewLast Update: 1 Dec 2006 - reviewed for CIAO 3.4: include link to the Creating a New Observation-Specific HRC Bad Pixel File thread Synopsis: Several of the CIAO data analysis tools directly use calibration data from the tool's parameter file, but many access it via calls to the ardlib.par parameter file. Although the majority of these calibration files are now controlled by the Chandra Calibration Database (CALDB), the observation-specific bad pixel list must still be set by the user. This list contains both the known bad pixels and columns for each chip, plus any additional ones for that specific observation. Purpose: To set the observation-specific bad pixel file for an analysis session. This ensures that the tools will locate the proper bad pixel file in ardlib.par when it is needed. Read this thread if: you are beginning a new ACIS or HRC analysis session. Related Links:
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Contents
- Get Started
- Reminder: Reset ardlib Between Analysis Sessions
- ACIS Observations
- HRC Observations
- Check the Local ardlib.par File
- Summary
- Parameter files:
- History
Get Started
Sample ObsIDs used: 1843 (ACIS-I, G21.5-0.9); 144 (HRC-I, G21.5-0.9); 1557 (HRC-S, G21.5-09)
File types needed: evt2; bpix1
If you have created a new bad pixel file by following one of these threads:
- Create a New ACIS Bad Pixel File: Identify ACIS Hot Pixels and Cosmic Ray Afterglows thread
- Creating a New Observation-Specific HRC Bad Pixel File thread
use that file in this thread. Otherwise, use the bpix1.fits file from the Archive.
In the following examples, these filenames will be used:
-
ACIS: /data/ObsID1843/acis1843_new_bpix1.fits
(created with the ACIS hot pixel tools) -
HRC-I: /data/ObsID144/secondary/hrcf00144_000N003_bpix1.fits
-
HRC-S: /data/ObsID1557/secondary/hrcf00144_000N003_bpix1.fits
Reminder: Reset ardlib Between Analysis Sessions
Use caution when analyzing more than one dataset; either "punlearn" or delete the ardlib.par file before you start processing another dataset.
If you find that tools/scripts complain about being unable to find the bad pixel file for an observation that is different from the one you are observing, chances are that you have not cleaned out your ardlib.par file.
ACIS Observations
The process of setting the bad pixel parameters for an ACIS observation has been simplified with the acis_set_ardlib script. If users prefer, it is also possible to set the parameters manually.
Download the script
This section of the thread uses the acis_set_ardlib script. The most recent version of acis_set_ardlib is v1.5 (07 January 2005):
unix% grep Id `which acis_set_ardlib` % $Id: acis_set_ardlib,v 1.5 2005/01/07 20:03:07 dburke Exp $
Please check that you are using the most recent version before continuing. If you do not have the script installed or need to update to a newer version, please refer to the Scripts page.
Running acis_set_ardlib
Prior to version 1.5, the script would look for a file that ended in "bpix1.fits" in the current and ../secondary/ directories. The script now requires you to supply the full filename. This change was made to allow easy use of the output from acis_run_hotpix, as the new bad pixel file is not required to end in bpix1.fits.
The absolutepath parameter ("yes" by default) tells the script to include the complete path to the file in ardlib.par, as shown in this example:
unix% punlearn ardlib unix% pwd /data/ObsID1843 unix% acis_set_ardlib acis1843_new_bpix1.fits Updated ardlib parameter file: /home/username/cxcds_param/ardlib.par AXAF_ACIS0_BADPIX_FILE -> /data/ObsID1843/acis1843_new_bpix1.fits[BADPIX0] AXAF_ACIS1_BADPIX_FILE -> /data/ObsID1843/acis1843_new_bpix1.fits[BADPIX1] AXAF_ACIS2_BADPIX_FILE -> /data/ObsID1843/acis1843_new_bpix1.fits[BADPIX2] AXAF_ACIS3_BADPIX_FILE -> /data/ObsID1843/acis1843_new_bpix1.fits[BADPIX3] AXAF_ACIS4_BADPIX_FILE -> CALDB AXAF_ACIS5_BADPIX_FILE -> CALDB AXAF_ACIS6_BADPIX_FILE -> /data/ObsID1843/acis1843_new_bpix1.fits[BADPIX6] AXAF_ACIS7_BADPIX_FILE -> /data/ObsID1843/acis1843_new_bpix1.fits[BADPIX7] AXAF_ACIS8_BADPIX_FILE -> CALDB AXAF_ACIS9_BADPIX_FILE -> CALDB
It is recommended that the script be run with absolutepath=yes so that the correct bad pixel file is accessed, regardless of the working directory.
The content of the parameter file may be checked using plist acis_set_ardlib.
Optional: Setting the ACIS parameters manually
If you prefer, it is possible to set the ARDLIB parameters manually instead. First determine which chips were on for the observation, then set the appropriate parameters:
unix% dmkeypar acisf01843N001_evt2.fits DETNAM echo+ ACIS-012367 unix% foreach d ( 0 1 2 3 6 7 ) foreach? pset \ ardlib AXAF_ACIS${d}_BADPIX_FILE = \ "/data/ObsID1843/acis1843_new_bpix1.fits[BADPIX${d}]" foreach? end
HRC Observations
Setting the bad pixel file for HRC observations is straightforward, as there is only one ARDLIB parameter each for HRC-S and HRC-I.
- HRC-I
-
unix% pset ardlib \ AXAF_HRC-I_BADPIX_FILE=/data/ObsID144/secondary/hrcf00144_000N003_bpix1.fits
- HRC-S
-
unix% pset ardlib \ AXAF_HRC-S_BADPIX_FILE=/data/ObsID1557/secondary/hrcf01557_000N002_bpix1.fits
Check the Local ardlib.par File
Verify that ardlib.par now references the correct bad pixel files (this example shows the files for all three detectors):
unix% plist ardlib | more Parameters for /home/username/cxcds_param/ardlib.par # Ardlib parameter file # Non-absolute file names are searched in the directories given # by the ArdlibDataPath variable. ArdlibDataPath = $ASCDS_CALIB Directory containing data files #=========================================================================== # Generic Mission Support #=========================================================================== . . (lines omitted) . #--------------------------------------------------------------------------- # AXAF ACIS Bad Pixel Files # Use "NONE" to ignore bad pixels. #--------------------------------------------------------------------------- AXAF_ACIS0_BADPIX_FILE = /data/ObsID1843/acis1843_new_bpix1.fits[BADPIX0] Enter ACIS-0 Bad Pixel File AXAF_ACIS1_BADPIX_FILE = /data/ObsID1843/acis1843_new_bpix1.fits[BADPIX1] Enter ACIS-1 Bad Pixel File AXAF_ACIS2_BADPIX_FILE = /data/ObsID1843/acis1843_new_bpix1.fits[BADPIX2] Enter ACIS-2 Bad Pixel File AXAF_ACIS3_BADPIX_FILE = /data/ObsID1843/acis1843_new_bpix1.fits[BADPIX3] Enter ACIS-3 Bad Pixel File AXAF_ACIS4_BADPIX_FILE = CALDB Enter ACIS-4 Bad Pixel File AXAF_ACIS5_BADPIX_FILE = CALDB Enter ACIS-5 Bad Pixel File AXAF_ACIS6_BADPIX_FILE = /data/ObsID1843/acis1843_new_bpix1.fits[BADPIX6] Enter ACIS-6 Bad Pixel File AXAF_ACIS7_BADPIX_FILE = /data/ObsID1843/acis1843_new_bpix1.fits[BADPIX7] Enter ACIS-7 Bad Pixel File AXAF_ACIS8_BADPIX_FILE = CALDB Enter ACIS-8 Bad Pixel File AXAF_ACIS9_BADPIX_FILE = CALDB Enter ACIS-9 Bad Pixel File #--------------------------------------------------------------------------- # AXAF HRC-I #--------------------------------------------------------------------------- AXAF_HRC-I_QE_FILE = CALDB Enter HRC-I Mean QE file AXAF_HRC-I_QEU_FILE = CALDB Enter HRC-I Mean QE file AXAF_HRC-I_BADPIX_FILE = /data/ObsID144/secondary/hrcf00144_000N003_bpix1.fits Enter HRC-I Badpix file #--------------------------------------------------------------------------- # AXAF HRC-S #--------------------------------------------------------------------------- AXAF_HRC-S1_QE_FILE = CALDB Enter HRC-S1 Mean QE file AXAF_HRC-S2_QE_FILE = CALDB Enter HRC-S2 Mean QE file AXAF_HRC-S3_QE_FILE = CALDB Enter HRC-S3 Mean QE file AXAF_HRC-S1_QEU_FILE = CALDB Enter HRC-S1 QE Uniformity file AXAF_HRC-S2_QEU_FILE = CALDB Enter HRC-S2 QE Uniformity file AXAF_HRC-S3_QEU_FILE = CALDB Enter HRC-S3 QE Uniformity file AXAF_HRC-S_BADPIX_FILE = /data/ObsID1557/secondary/hrcf01557_000N002_bpix1.fits Enter HRC-S Badpix file . . (lines omitted) .
Note that the parameter file now resides in the local parameter directory (/home/username/cxcds_param) as a result of the pset steps. All the CIAO tools will now access this version rather than the default one.
Summary
Again, remember to "punlearn" or delete your ardlib.par file after completing analysis of this dataset to ensure that the proper bad pixel maps are used the next time that ardlib.par is referenced by a tool.
Parameters for /home/username/cxcds_param/acis_set_ardlib.par badpixfile = acis1843_new_bpix1.fits Bad pixel file for the observation (absolutepath = yes) Use an absolute path in the parameter file (ardlibfile = ardlib) Parameter file to change (verbose = 1) Verbosity (0 for no screen output) (mode = ql) |
History
05 Jan 2005 | updated for CIAO 3.2: ardlib.par has new contamination file parameters; added information on creating a new bad pixel file with the acis hot pixel tools |
20 Jan 2005 | revised to use new version of the acis_set_ardlib script; separated ACIS and HRC sections |
08 Dec 2005 | reviewed for CIAO 3.3: no changes |
01 Dec 2006 | reviewed for CIAO 3.4: include link to the Creating a New Observation-Specific HRC Bad Pixel File thread |