Chandra X-Ray Observatory
	(CXC)
Skip to the navigation links
Last modified: 17 July 2017

URL: http://cxc.harvard.edu/ciao/bugs/reproject_image_grid.html

Bugs: reproject_image_grid


Table of Contents

Caveats

Bugs


Caveats

Setting the pixelsize to a value in arcseconds

If you are setting the reproject_image_grid pixelsize parameter to a value in arcseconds, you have to specify it when the tool is run, not via pset.

A feature in the CIAO parameter interface causes double quotes (") to be converted to single quotes (') when they are written to the parameter file:

unix% pset reproject_image_grid pixelsize='1"' 
unix% pget reproject_image_grid pixelsize
1'

Supplying the pixelsize on the command line when the tool is run ensures that the value will be correctly interpreted as arcsec, e.g.

unix% reproject_image_grid pixelsize='1"' 
Input image file name (@expmaps.lis): 
.. etc. ..

The value is also correctly recorded in the history of the output file:

unix% dmhistory sn1006_expmap.fits reproject_image_grid
reproject_image_grid infile="@list_of_expmaps.lis" outfile="sn1006_expmap.fits"
xsize="2500" ysize="2500" xcenter="225.7" ycenter="-41.9" theta="0" pixelsize="1""  
projection="tan" resolution="1" method="average" coord_sys="world"  
lookupTab="/soft/ciao/data/dmmerge_header_lookup.txt" clobber="yes" verbose="0" 

Bugs

Incorrect results when using -0 Dec in sexagesimal format

[New] (17 Jul 2017) reproject_image_grid fails to correct parse the negative sign when working with -0 deg Declination values in sexagesimal format. For example

unix% reporject_image_grid in.img out.img xcenter=10:20:30 ycenter=-0:10:20 coord=world ...

This bug does not affect negative declination values greater than 0 ( -1 to -90) and does not affect values in decimal degrees.

Workaround:

The work around is to convert the coordinates to decimal degrees

unix% prop_precess f j/hms t j/deg p0 eval 10 20 30 -0 10 20 
155.125000    -0.172222
unix% reporject_image_grid in.img out.img xcenter=155.1250 ycenter=-0.172222 coord=world ...

Last modified: 17 July 2017
Smithsonian Institute Smithsonian Institute

The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email:   cxchelp@head.cfa.harvard.edu Smithsonian Institution, Copyright © 1998-2017. All rights reserved.