Re: Data Processing Switch

[Tom Droege <tdroege2@earthlink.net>]

The proposal is to save the corrected .fits files.

These have:

1) Dark Subtraction
2) Flat Fielding using a light box.
3) Removal of edges and bad pixel areas
4) A correction to make the image as flat as possible to remove the sky 
gradient.  This is presently a first order correction.  I believe the 
values used are recorded so this could be undone.  I think the flat and 
dark fields used are not saved anywhere but my log books.  Possible choices 
are a zero order, first order or second order flattening correction.
5) A center of the field position for (I recall) CRVAL0 and CRVAL1.

Now if some others were running their telescopes and reducing data then we 
could have a real debate on this topic.  There would be others that were 
looking at real data with me and struggling with the right compromise.

Tom Droege


At 01:25 PM 6/2/03 -0700, Chris Albertson wrote:

>There may be a mis-understanding here.  What I thought Tom
>proposed to save was a FITS file with un-processed pixels
>(except for trimming the overscan) and corrected values
>in the header. If that's true: raw pixels and "corrected"
>headers then nothing is lost.  Such files should be able
>to be re-processed.
>
>We will have to wait 'till Tom clarifies this for us by
>tell us what's in the FITS files.
>
>I read Micheal's pipeline documentation over lunch.  Looks
>like he writes only the image center and image scale into
>the FITS header.  I think this should be expanded to include
>a full astrometric solution including the rate of change in
>image scales in X and Y and rotation.  This is required for
>any off-the-equator image.
>
>
>
>--- Arne Henden <aah@nofs.navy.mil> wrote:
> > Additions to Rob's comments
> >    - you could find new dust donuts appearing if you don't take
> >      flats every night, and need to go back to see when the
> >      donut occurred and reprocess starting at that point
> > My feeling is to save the raw images and discard the processed
> > images after you have done the star extraction.  That way you
> > save the same amount of data, but can recreate anything.
> > Arne
> >
> > Creager, Robert S wrote:
> > >
> > >>-----Original Message-----
> > >>From: Tom Droege [mailto:tdroege2@earthlink.net]
> > >>Sent: June 02, 2003 7:29 AM
> > >>
> > >>The proposal is to save the dark subtracted, flat fielded,
> > >>and position
> > >>corrected files which come out of Michael R's pipeline
> > >>instead.  These
> > >
> > >
> > > I would say apply the location correction to the original images,
> > and keep
> > > those.  I've offered to write a script that does this (take the
> > pipeline
> > > output and update the original FITS headers).
> > >
> > >
> > >>data reduction.  There is no way to get a better flat or dark
> > >>later in
> > >>time.  I don't know what else we might want to do.
> > >
> > >
> > > Sure there is.  Better reject/selection criteria of images used for
> > > generating flats or darks...
> > >
> > > Cheers,
> > > Rob
> > >
> > >
> > >
> >
> >
> >
>
>
>=====
>Chris Albertson
>   Home:   310-376-1029  chrisalbertson90278@yahoo.com
>   Cell:   310-990-7550
>   Office: 310-336-5189  Christopher.J.Albertson@aero.org
>   KG6OMK
>
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