Ximage

Mosaics

XIMAGE can be used to take several images from a part of the sky and make a mosaic. The first image must be read in with the center and size required for the final image. It is best to begin with a central image if possible.

Use the following procedure:

  • READ in the first image with the center and size desired for the completed image
  • SAVE the image
  • READ in the second image with the same size
  • SUM the images
  • SAVE the resulting image
  • READ in the third image with the same size
  • SUM the images
  • SAVE the resulting image
  • Repeat READ,SUM,SAVE operations for all images

Image of the Perseus Cluster mosaiced together from separate observations

The following scripts was used to create the image above:


read/fits/size=1024/xpix=6000/ypix=2500 rp800035_im1.fits
read/fits/expo/size=1024/xpix=6000/ypix=2500 rp800035_mex.fits
save_image
read/fits/size=1024 rp800033_im1.fits
read/fits/expo/size=1024 rp800033_mex.fits
sum_image
save_image
read/fits/size=1024 rp800034_im1.fits
read/fits/expo/size=1024 rp800034_mex.fits
sum_image
save_image
read/fits/size=1024 rp800032_im1.fits
read/fits/expo/size=1024 rp800032_mex.fits
sum_image
cct/set spectrum
lev/num=32
title " "
title/lower " "
disp/log
vplabel "Perseus Cluster"

If exposure maps are available, read them in after each image with the exact size and center of the image they belong with. The exposure maps will be summed together when the image maps are summed.

DETECT and SOSTA will not give the correct results if the summed images come from different pointing directions. They will be unable to make any correction for off-axis vignetting and psf changes, since they reference to the detector coordinates of the last image that was read in.


Ximage Home Page Xanadu Home Page Xanadu ftp site

Please send reports of errors to : xanprob@athena.gsfc.nasa.gov

HEASARC Home | Observatories | Archive | Calibration | Software | Tools | Students/Teachers/Public

Last modified: Wednesday, 29-Mar-2006 14:33:21 EST