[ATM] Similar problem with reflections

[RP <rp@suttonsonline.us>]

I have a 10" F/7 DOB and I noticed the last 2 times that I observed with 
it  that about 2 or 3 am, after I had been observing for about 5 hours, 
I started getting an additional image in the eyepiece - a reflection it 
seems like. It is a fairly large and looks exactly like the the image I 
would get with my focuser racked all the way out - a large circle with 
the shadow of the secondary in the middle. It moves as I move my eye but 
does not seem to change if I turn the eyepiece in the focuser. It also 
is present in multiple eyepieces from orthos to widefields. Any idea 
what this is? could it be caused by dew on the secondary? That is my 
suspicion but I since I o not know what the effects of dew on the 
secondary would be, its just a guess.  In any event, these images do not 
appear until after several hours of observing.

Thanks  for your help -

RP

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