[Aavso-photometry] RE: Where do the professionals source (arne)

[David Higgins]

'Not practical for a working observatory'???  Of course this depends on what
you classify as a working observatory but I remove my cameras every night
simply because they are small and easily transportable items for thieves (a
14" telescope isn't).  The camera always goes back to within 0.4 degree
rotation (camera/scope mount adapter takes care of that) and I always
perform a focus (as should any observatory) before the imaging session
begins.  I've done this for 100+ sessions over the last 3 years with no ill
effects.

I can understand why observatories with LN DEWARs etc will not remove the
cameras but there really isn't any valid reason otherwise if you want to
maintain the integrity of your filters.  

If the filters are degrading and you have to change them then your data then
becomes suspect because you have no idea at what point they become suspect!
Whats more important - data integrity or a small inconvenience each session?

Cheers

David Higgins
E14
Canberra, Australia
http://users.bigpond.com/higginsdj

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Subject: Aavso-photometry Digest, Vol 22, Issue 15


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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.
>