[Aavso-photometry] Where do the professionals source

[arne]

Michael Koppelman wrote:

> This is, of course, not practical for a working observatory. I touch  
> my CCD/focus as little as possible. I'm certainly not going to  
> unmount the CCD every night. Given that this seems to be a reality it  
> sounds like I have to treat my V filter as a consumable resource and  
> just buy a new one every few years.
>
> It's funny because I have a Custom Scientific filter that I haven't  
> used in probably 3 years and it is in perfect condition -- no gunk.  
> This situation must be a result of varying temperature/humidity  
> because the filter in question has been stored without desiccant for  
> years and shows no degradation. I had previously stored it in my  
> observatory and still it had no degradation. This makes me wonder if  
> the problem isn't aggravated in some filters over others.
>
Turns out that I will be giving a filter paper at the Fall AAVSO 
meeting, in collaboration with
Don Goldman and Chet Schuler.  We will discuss this filter problem and 
possible solutions.
Arne