[Aavso-photometry] Cosmic Rays

[Michael Newberry]

Wolfgang,

Can you elaborate a little on what you are describing? Are you wanting to a) 
combine the images having the largest deviant, or b) reject the largest 
deviant from the combination?

Michael Newberry

----- Original Message ----- 
From: "Wolfgang Renz" <w_renz at onlinehome.de>
To: "Ben Davies" <ben at davies.net>
Cc: <aavso-photometry at mira.aavso.org>
Sent: Friday, January 27, 2006 5:06 PM
Subject: Re: [Aavso-photometry] Cosmic Rays


> Hi Ben
>
> If you average/sum combine the differential images, you'll lower
> the detectability of the artifacts as they will just appear in a
> single image. If you combine 10 images, its just 1/10 of the
> difference in the affected original, if you combine 100 images,
> its just 1/100.
>
> Using something like a "higest absolute deviant combine"
> instead, should lead to much better results. I don't know if
> such an algo is implemented anywhere, but it should also
> be helpful in finding moving minior planets that are just barely
> above the background.
>
> 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: Friday, January 27, 2006 10:07 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/
>>
>> _______________________________________________
>>
>> Aavso-photometry mailing list
>> Aavso-photometry at mira.aavso.org
>> http://www.aavso.org/mailman/listinfo/aavso-photometry
>
> _______________________________________________
>
> Aavso-photometry mailing list
> Aavso-photometry at mira.aavso.org
> http://www.aavso.org/mailman/listinfo/aavso-photometry
>
>