hriaspcor HEADAS help file

NAME

hriaspcor -- Use Morse's method to correct aspect errors in large photon event lists from HRI.

USAGE

hriaspcor infile outfile iwobbin mincnts

DESCRIPTION

Reads an HRI events list and uses the algorithm of Jon Morse to correct the standard aspect solution for detector "wobble". See (Morse, PASP 1994) for details of the algorithm. Writes a new events list with corrected values of X and Y (actual sky position). If the copyall parameter is set to true, the new file should be identical to the old one except for the X and Y columns in the "good" events table and the necessary keyword changes in the headers. Default values of the parameters assume an RDF file. Previously released data sets use FITS extension [3] and detector coordinate column names DX and DY. It is recommended that the "dewobbling" bin size should correspond to ~10", and the mincnts parameter should not be less than 100. Note, this technique will fail for extended sources (i.e. anything with a real size larger than the "dewobbling" bin size.

PARAMETERS

infile [filename]: The input FITS file name and extension.
outfil [filename]: The output FITS file name. The new table will be in the same extension as it was in infile. (Unless copyall=no, then it will be in extension 1.)
iwobbin [integer]: The binning size for taking centroids and restacking ("dewobbling"). Recomended size: approximately 10", or about 20 pixels.
mincnts [real]: Minimum number of counts in a valid "dewobbling" bin. Recommended: at least 100.
(xcol = 'RAWX') [string]: The name of the column containing the detector X coordinates.
(ycol = 'RAWY') [string]: The name of the column containing the detector Y coordinates.
(xcolcor = 'X') [string]: The name of the column containing the X sky coordinates.
(ycolcor = 'Y') [string]: The name of the column containing the Y sky coordinates.
(xrange = 'INDEF,INDEF') [string]: The X range of valid pixels in detector coordinates (note: not sky coordinates).
(yrange = 'INDEF,INDEF') [string]: The Y range of valid pixels in detector coordinates (note: not sky coordinates).
(copyprime=yes) [boolean]: Whether to copy all additional keywords from the primary array of input file to the primary array of the output file.
(copyall=yes) [boolean]: Whether to copy all other HDUs from the input file to the output file.
(clobber=no) [boolean]: Whether to overwrite an existing output file.

EXAMPLES

To make a Morse-corrected version of an RFD file rh141873n00_bas.fits

ft>hriaspcor rh141873n00_bas.fits rh141873n00_bas_m.fits 20 100

To make a Morse-corrected table of the events from an old format (US Rev0) HRI file rh160093.fits and write it as the only extension in a file called meaty.fits

ft>hriaspcor rh160093.fits[3] meaty.fits 20 100 copyall=no xcol="DX" ycol="DY"

NOTES:

If more than one bright source is in the field, you must use the xrange and yrange parameters to isolate the source of interest.

KNOWN BUGS

Does not treat each orbit separately as specified in Morse's paper.

Subimage centroids are calculated by finding the center of gravity of the entire subimage rather than just the central 3" (i.e. unlike in Morse, no radial brightness profiles are calculated).

LOG OF SIGNIFICANT CHANGES

v1.1 (1994 Sept.): Added warning if zero counts, changed clobber to match new ftools standard and added some new documentation.
v1.0.0 (1994 July): Original version.

PRIMARY AUTHOR

Lawrence E. Brown

Hughes STX for

NASA/GFSC

http://heasarc.gsfc.nasa.gov/cgi-bin/ftoolshelp

(301) 286-4996