Re: FITS tables

["Glenn Gombert" <glenngombert@hotmail.com>]

My port of the Mark IV processing program (which I did some moths bacK) 
supports outputting Mark IV start-lists in FITS ASCII Table format...and 
ought to sever a good 'baseline' for putting out Mark IV data in FITS Table 
Format...

Glenn G.


>From: Jure Skvarc <jure.skvarc@ijs.si>
>To: TASS mailing list <TASS@LISTSERV.WWA.COM>
>Subject: Re: FITS tables
>Date: Mon, 06 Nov 2000 17:59:59 +0100
>
>I promised to be busy with my work, but let me have some further questions.
>
>In the star list fields, there are quantities FWHM[XY], ROUNDNESS and 
>SHARPNESS.
>FWHM is a parameter which can be naturally derived from the PSF function, 
>like
>2.35*sigma for a (1D) gaussian etc.  I wonder what are the PSF functions 
>used
>for images with noticeable coma like TASS images and how do you define 
>FWHMX and
>FWHMY. Are X and Y meant along x, y axis of the images or are they along 
>the
>minor and major axis of the blob (star)?
>
>Now I will risk to expose all my ignorance, but I am interested in this
>subject.  How is the roundness defined?  Probably everybody else knows this
>because no one complains by saying "my software does not compute this!" and 
>this
>field is supposed to be required.   Next, how exactly is the sharpness 
>defined?
>The closest thing to this that I remember is expressed by <x^4> and <x^2>, 
>where
><> means expectation values, but I don't know the exact formula right now.  
>In
>any case, unless these things are well defined, I see no sense to make them 
>the
>requested quantities.
>
>Also, do all software packages aspiring to process Mark IV images compute 
>both
>aperture magnitude and PSF fitted magnitude?  If not, they are out of the 
>game
>until they are updated to do this.
>
>Now to the Tom's comment:
>
>
> > I have one comment.  Should not the header include the processing steps
> > applied to the data?  For example, we might have a star list, then a 
>star
> > list corrected for air mass.  I would show this by simply listing in the
> > etc...
>
>Yes, it is quite common to indicate any data manipulation using HISTORY 
>keywords
>in the FITS header.  It would be a good idea to continue with this praxis, 
>maybe
>like:
>HISTORY ACTION:  Calculate sky coordinates
>HISTORY Performed by  XYZ program version 5.3
>HISTORY Date of operation 2000-11-29
>
> > If the below is acceptable to all, then I would like to make it a TN, 
>and
> > get on with processing data.  Please make objections as soon as
> > possible.  Note this is just the format for exchanging star lists.  
>There
> > will be other formats for images.
> >
>I think we should wait with this definition until major players in this
>processing business accept (or reject) this.
>
>
>Also, I will repeat my question from one of the previous emails.  Is it a
>realistic scenario to shuffle half-processed star lists with millions of 
>stars
>all around the planet until they are well analyzed or is it better to do
>complete processing at the site which produced the data?  I understand 
>Arne's
>concern that the whole and correct processing is a complicated task which 
>must
>be performed carefully.  But isn't this one of the things that operators 
>will
>just have to learn or accept other people's pipelines?
>
>
>				Jure
>

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