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Hi - I'd like to access some images in IRAF using a URL, which I believe is now a built-in capability of IRAF 2.16. In particular, I'd like to do things such as those shown in this interesting video put up on YouTube by the USVAO folks:

https://www.youtube.com/watch?v=qOwqjTHqHkU&t=54s

I'm using IRAF 2.16 installed using Astroconda but am failing at the first hurdle. For example, here's an attempt to do the first thing shown in the video, which is to run imstat on a publicly available image:

ecl> imstat http://www.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/data/pub/CFHT/1722795p.fits[24][520:990,2420:2782]
# IMAGE NPIX MEAN STDDEV MIN MAX
ERROR: Attempt to delete a nonexistent file (cache$/.f1080901112)

I've verified that I can access the image (in this case a CFHT image available on the CADC site) using a web browser, so the I think the URL is fine.

The volume of parameter space encompassing "Bob is doing something stupid here" is huge... could somebody help me narrow it down?

Thank you,

Bob Abraham

P.S. Part of the problem is probably my failure to RTFM but I'm having difficulty finding documentation for the IRAF VO stuff. Is it documented as part of the IRAF help system?