[Aavso-photometry] Cosmic Rays

[Wolfgang Renz]

Hi Ben

If a cosmic ist falling into the sky annulus, is often not too serious as
most (advanced) photometry packages have implemented some
kind of outlier rejection.

Cosmics falling into the star aperture should be more serious as
they can be detected just with more complexity (that is not
implemented in most photometry packages) and therefore are
ignored in most cases if they are not detected visually.

Clear skies
  Wolfgang

-- 
Wolfgang Renz, Karlsruhe, Germany
Rz.BAV = WRe.vsnet = RWG.AAVSO



----- Original Message ----- 
From: "Ben Davies" <ben at davies.net>
To: <aavso-photometry at mira.aavso.org>
Sent: Saturday, January 28, 2006 1:39 AM
Subject: Re: [Aavso-photometry] Cosmic Rays


> ...
> 
> You would prefer not to have any of these falling inside the outer 
> annulus, so I guess 'nearby' is as good a term as any.
> 
> Ben
> 
> 
> 
> > Can you please explain exactly what your goal is? Are you trying to 
> > avoid measuring a star in an image if there is a cosmic ray nearby?
> >
> > Michael Newberry
> >
> >
> >
> > ----- Original Message ----- From: "Ben Davies" <ben at davies.net>
> > To: <aavso-photometry at mira.aavso.org>
> > Sent: Friday, January 27, 2006 2:07 PM
> > Subject: Re: [Aavso-photometry] Cosmic Rays
> >
> >> Here is a method I've come up with to analyze cosmic ray hits in 
> >> photometric images:
> >>
> >> - Make a median of all images.
> >> - Subtract this median from each of the images to get a set of images 
> >> that contain all the artifacts.
> >> - Average combine (or add, depending)  the artifact set.  Now one 
> >> image contains the defects and another contains the signal..
> >> - Blink the averaged image against the median.
> >>
> >> If no artifacts fall on or near the stars you are interested in, the 
> >> job is done.
> >> If an artifact does coincide, you just track down the offending image.
> >>
> >> I'm probably just stating the obvious here, but it took me a while to 
> >> figure it out
> >>
> >> Ben Davies
> >> http://ben.davies.net/