RGB Image Overlays using SkyView clients

SkyView provides two ways to generate images on local machines – the java based SkyView-in-a-Jar application and the Perl based skvbatch program. Most tasks are straight forward using either client.

java -jar skyview.jar Position=m101  survey=DSS Return=jpg size=.25 Pixels=500 output=java_out

skvbatch Position=m101  Survey=DSS Return=jpg Size=.25 Pixels=500  file=skvbatch_out.jpg

Creating RGB images using the SkyView-in-a-Jar application is also straight forward:

java -jar skyview.jar Survey=DSS1R,DSS,DSS1B rgb Return=jpg output=java_m101 Position=m101 Size=.25 Pixels=500

However creating the same image using the skvbatch program is a bit more involved.    The skvbatch script was designed to return a single output file. With RGB requests there are four images produced – 3 FITS files and one image file.  To retrieve the image file the RETURN=filename parameter setting can be used to retrieve the name “stem” of the file and then URLs can be built to retrieve any of the files.

If, for example, skvbatch returns a value XXX then the four files are:

http://skyview.gsfc.nasa.gov/tempspace/fits/XXX_1.fits
http://skyview.gsfc.nasa.gov/tempspace/fits/XXX_2.fits
http://skyview.gsfc.nasa.gov/tempspace/fits/XXX_3.fits
http://skyview.gsfc.nasa.gov/tempspace/fits/XXX_rgb.jpg

With this “stem” you can easily retrieve the JPEG image directly.  Here  is a little C shell script that you can use to get RGB JPEGs:

#!/bin/csh
   
set name=`skvbatch survey=dss,dss2b,dss2r rgb=t position=3c273 return=filename`

wget http://skyview.gsfc.nasa.gov/tempspace/fits/${name}_rgb.jpg -O rgb.jpg

For more information please visit the Running SkyView on Your Machine page.