From: <waltc
Date: Fri, 7 Apr 2006 14:17:39 -0400

Do be very careful if you decide to bin for photometry.  It's too easy to fall prey to the subtle problem where one pixel is saturated but the binned pixel is not.  You are actuallly introducing a significant error into your photometry because you are clipping off some of the photons and you can't even tell.  I believe the difference in read noise between 1x1 and 2x2 is small so I don't know that it is worth the risk.  You may actually lose some S/N by doing it.  One of the tricks used for millimag photometry is to oversample with very large fwhm.

-Walt Cooney

> 
> From: "Tom Krajci" <tom_krajci
> Date: 2006/04/07 Fri PM 12:31:13 EDT
> Date: 2006/04/07 Fri PM 12:31:13 EDT
> 
> >From: "Chris Sauer" <chris
> 
> >First off, I was amazed at how much the V filter attenuates the
> >light.  In 1 X 1 binning, I needed three minute subs to get decent ADU
> >counts on RS Leo itself.
> 
> I looked at your image.  Considering the size of your star profiles (Full
> That may boost your SNR on faint stuff because there is less read noise.
> It's worth a comparison or two versus 1x1 binned images on the same evening.
> (And I'd be interested in hearing of your results.)
> 
> >Also, what's the best way to perform the photometry?
> 
> What software package do you have?  Most amateurs use software that does
> aperture photometry, not PSF fitting photometry.  However there is some
> software out there that does PSF fitting photometry.  If your star field is
> not crowded, then aperture photometry usually will satisfy the requirement.
> 
> 
> Tom Krajci
> Cloudcroft, New Mexico
> http://overton2.tamu.edu/aset/krajci/
> 
> 
> 
> 
> No virus found in this outgoing message.
> Checked by AVG Free Edition.
> Version: 7.1.385 / Virus Database: 268.3.5/303 - Release Date: 4/6/2006
> 
> _______________________________________________
>