[Aavso-photometry] Cosmic Rays

[Ben Davies]

Hi Michael,

I measure cosmic ray levels from as low as half a dozen electrons all 
the way up to saturation.  Sometimes the hits are big and bright and 
fade to low levels.  Sometimes they are very low level from start to 
finish - no more than a couple hundred electrons in the brightest pixel.

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/
>>