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Last modified: 26 October 2020


Bugs: tgsplit

Table of Contents



For TYPE:II PHA files created with tgextract2 the BACKSCAL values in the background PHA file are wrong.

The background scaling column BACKSCAL in the background PHA files created from the tgextract2 output incorrectly have the source region BACKSCAL values. This leads to the background being incorrectly scaled when the data are fitted.

This only occurs with PHA2 files created with the advanced tgextract2 tool; standard analysis threads, including chandra_repro, use the original tgextract tool. Users can check the CREATOR keyword to see which tool was used:

unix% dmkeypar random_pha2.fits CREATOR  echo+
tgextract2 - Version CIAO 4.X

Users using tgextract2 should use opt=pha1 to produce individual TYPE:I PHA files.

ARF and RMF are not automatically associated with individual PHA files for ACIS Continuous Clocking mode datasets.

The ARF and RMF files for ACIS continuous clocking mode observations contain the keyword: CYCLE = 'P'. This keyword is reserved for TIME mode observations, and is not present in the PHA files. This mis-match means that the ARFs and RMFs cannot be automatically matched with the individual PHA files.

unix% tgsplit infile='acisf00689_repro_pha2.fits' arffile='tg/*arf*' rmffile='tg/*rmf*' outroot='tg/acisf00689_repro' 
Created background spectrum: tg/acisf00689_repro_meg_p1_bkg.pha
Created background spectrum: tg/acisf00689_repro_meg_p2_bkg.pha
Created background spectrum: tg/acisf00689_repro_meg_p3_bkg.pha
Cannot find ARF file for MEG -2
Cannot find RMF file for MEG -2
Cannot find ARF file for HEG -1
Cannot find RMF file for HEG -1
Cannot find ARF file for HEG +2
Cannot find RMF file for HEG +2
Cannot find ARF file for MEG +2


Users can work-around the problem by removing the CYCLE keyword from the ARF and RMF files.

unix% dmhedit "tg/*arf,tg/*rmf" file= op=del key=CYCLE