RE: fun with co-adding images on Disk Set 19

["Creager, Robert S" <CreagRS@LOUISVILLE.STORTEK.COM>]

Fine words of wisdom.  I guess I really need to re-install IRAF and attempt
to hurdle the learning curve...  Chris did have a good idea a while ago,
using a unique user for the install.

Thanks,
Rob


> -----Original Message-----
> From: aah@nofs.navy.mil [mailto:aah@nofs.navy.mil]
> Sent: Tuesday, October 16, 2001 3:00 PM
> To: tass@listserv.wwa.com
> Subject: RE: fun with co-adding images on Disk Set 19
> 
> 
> Rob,
>   Your technique of matching stars, then coadding, is what
> most image processing packages do (such as the nice iraf
> package immatch).
>   One thing you need to watch for is that an incorrect
> polar alignment not only causes drift on the CCD, but also
> rotation.  I had to rotate as well as translate all of my
> images that made up the M31 composite.  In addition, you
> want partial-pixel alignment, which means you have to decide
> what algorithm you want to use for interpolation.  I'd
> recommend looking at how iraf does it (imshift is the
> appropriate routine).  Personally, this is a lot of work
> and I'd rather use a standard image processing package to
> do such reductions than to roll my own.
> Arne
>