[fitsbits] EXPOSURE

[Mike Nolan]

The Single Dish FITS convention (an old convention that has been
revived for use with aips++) specifies the keyword EXPOSURE, so that's
how all recent Arecibo data files have been written.  It also
specifies a time axis that will in any case I can think of be
single-pixel.  It would be nice to find a way to make the axis
multi-pixel, but there are numerous problems with that.

There are those who hope that if aips++ uses it, it will become
standard.  Whether that's true or not, I can't say.  If your other
choice is to make up the format yourself, I'd suggest that SDFits would
be a much better idea.  On the other hand, at the moment, I don't know
of anything but aips++ that reads it.


My other hope is to write files that IRAF can read and believe are
spectra directly, which maintaining all of the information important to
radio data; but I'm not yet terribly familiar with those parts of
IRAF.

The document for single-dish FITS is:
http://www.cv.nrao.edu/fits/documents/drafts/dishfits/dishfits.ps
and there are example files in that directory.  There's also a 
mailing list, but it's "low-traffic" (as in none in several years).


-Mike


>> I'm working on a radio spectral line data acquisition package and need to decide
>> what keyword to use for integration time. An example FITS file that I have from
>> the SEST telescope at La Silla uses OBSTIME. The OGIP Spectral File Format
>> specifies EXPOSURE.  Are there any other keywords in use for this parameter?
>> Is there any hint of a convergence on a standard?

---------------------------
Mike Nolan <nolan at naic.edu>
+1 787 878 2612x334  Fax: +1 787 878 1861
Arecibo Observatory / Cornell University
HC03 Box 53995, Arecibo, Puerto Rico 00612  USA