iraf.net

>From welty@astro.psu.edu Mon Jun 22 17:40:30 1992
Date: Mon, 22 Jun 92 20:00:32 EDT
From: "Alan Welty" <welty@astro.psu.edu>
To: valdes@noao.edu
Subject: Re: complaintHi Frank,
Thanks for the info. I figured that there was a reason that just
isn't obvious to the users. Perhaps there has been more written about the
changes that I missed or don't remember.
Anyway, it was a surprise to find the format gone. We (in our research
group) just finished bragging in KPNO and NSF proposals about software we have
that does wonderful things - but image access is via IMFORT and relies on
the APNUM keywords. Since any new data reduction will have the new format
(unless I do go back to newimred), I may have to just rewrite the code to
support it. It doesn't look too hard to do, really, but like I said - I'm
not looking forward to it.Alan>From valdes Tue Jun 23 08:58:00 1992
Date: Tue, 23 Jun 92 08:57:59 MST
From: valdes (Frank Valdes CCS)
To: welty@astro.psu.edu
Subject: Re: complaintHi Alan,There are two possible difficulties with trying to use the new format. The
first is to decode the wrapped attribute strings. It should be obvious
that the WAT keywords are taken in order (with the i_j denoting the axis
and sequence) and concatenated to form a very long string within which are
encoded the attributes (mostly the SPECn attributes in MULTISPEC which are
similar to the APNUM). The second problem is understanding the meaning of
the other WCS keywords which affect the interpretation. If you never use
image sections or anything to modify the original relation between pixels
and the wavelengths then it is straightforward. If any operation modifies
this however one needs to fold in the effects of the subsection. For
example the starting wavelength and wavelength per pixel remain unchanged
during an image section and the LTM/LTV keywords are used to transform from
the "logical" coordinates to the original "physical" coordinates to which
the w0/wpc apply. You should read "phelp onedspec.package" which describes
the SPEC attributes and something of the WCS interface. You might also
want to read "phelp mwcs$MWCS.hlp f+" which is a description of the IRAF
system WCS interface.Again, it is unfortunate that there is no simple support for user access
to the new format. Note that within scripts you could use SLIST which
produces lines that can be parsed with scan/scanf to give the same
info as the APNUM keywords. The problem, as I said previously, is that
this is read-only. I would be willing to help you out as much as I can.Cheers,
Frank