When making a mosaic, it is best to read in an exposure map for each image. The exposure map must be read in after the image. The following example repeats the mosaic desribed above, but includes an exposure map.
read/fits/size=800 file1.fits ! read the first image into a 800x800 array read/fits/exp/size=800 exp1.fits ! read the first exposure map (optional) save_image ! save the exposure map read/fits file2.fits ! read the second image read/fits/exp exp2.fits ! read the secon exposure map sum_image ! sum the 1st and 2nd images save_image ! save the summed image read/fits file3.fits ! read the third image read/fits/exp exp3.fits ! sum_image ! sum the 3rd with the saved image save_image ! save the mosaic disp ! display the mosiaced image grid 0.5 0.5 ! draw a skygrid in 0.5 degree steps disp/exp ! display the exposure map disp/cor ! display the exposure corrected image write/fits mosaic.fits ! write the mosaic to a fits file write/fits/exp mosaic_exp.fits ! write the exposure