Subject: Re: FITS header cards

From: bschlesinger at nssdca.gsfc.nasa.gov (BARRY M. SCHLESINGER)
Date: 20 Jan 1994 16:57 EDT

In article <2hjl8k$sl4 at organpipe.uug.arizona.edu>, ron at argus.lpl.Arizona.EDU (Ron Watkins) writes...
>I was wondering if there is support for using CRVAL and CRDELT within
>FITS tables? We have a data format that im looking into formatting into
>a FITS table. Each record (of our data) contains various values and an
>array. The values are of differing formats but the array is fixed at 126
>single precision values representing counts at some wavelength. I had
>wanted to use CRPIX, CRVAL, and CRDELT to specify the wavelengths for the
>array but it doesn't apply to any of the other values in the table row other
>than the array. Is there FITS support for doing this? I can only find
>references for CRVAL and such in the primary HDU of the FITS files. I couldn't
>find it for the FITS extensions. 

The above does not specify whether an ASCII table or a binary table is
intended.  The proposed structure appears to fit most naturally in an
extension of type BINTABLE, where the array could appear as a single
field.  There has been some talk, particularly within the single dish
community, of conventions for use of the terms CRVALn, CRPIXn and
CDELTn to describe an array contained in one field of a binary table. 
Perhaps one of the people involved could step forward and say where
this discussion stands. 

> By the way, is there any documentation for >the extension 'IMAGE' or
is it just too obvious to bother. 

A LaTeX version of the proposal is available by anonymous ftp from
nssdca.gsfc.nasa.gov, in the FITS directory. 

				Barry Schlesinger
				NSSDC/NOST FITS Support Office