iraf.net

I have a problem when dealing with images in excess of 2.15Gbytes (i.e., 2^31 bytes), as STSDAS and TABLES tasks won't work with them, but core IRAF tasks like imarith, imcopy, etc. are fine:vocl> imarith large_image.fits + 1 junk.fits
vocl> imcalc large_image.fits junk2.fits im1+1
ERROR: Cannot open file (starpc16.astro.l!/scratch/cjs/ultravista/large_image.fits)
vocl> xy2rd large_image.fits 1 1
ERROR: Cannot open file (starpc16.astro.l!/scratch/cjs/ultravista/large_image.fits)This is IRAF V2.16 running on 64-bit Scientific Linux 6. TABLES and STSDAS were re-installed by running "make stsdas" from /iraf/iraf/extern but that didn't help. It's not a problem with the image, as I can imcopy a bit of it (anything up to 2.15G and then imcalc and other STSDAS tasks work OK. I can also run imcalc on the full image on my MacOS10.7.It looks to be some sort of 32/64-bit issue but I'm not really sure how to further diagnose it or proceed. Any help would be much appreciated.

STScI made the decision to not support 64-bit platforms and so STSDAS and TABLES remain 32-bit binaries (and 2GB limited) even on 64-bit platforms. See their note at http://www.stsci.edu/institute/software_hardware/stsdas/iraf64Tasks like IMCALC have core equivalents in e.g. IMARITH or IMEXPR, see tasks in the IMMATCH core package for alternatives to XY2RD

Thanks for the reply. I am aware of the lack of a 64-bit version of STSDAS but I assumed that the fact that the STSDAS tasks work on the same large images under MacOS meant that couldn't be the cause.

It may simply mean the memory error triggered on the Mac system wasn't fatal to the task, even if you're sure the image wasn't corrupted on disk in this case you can't count on this to work every time.