[Aavso-photometry] UBV Photon Counting

[Richard Miles]

Jeff -  Long time no hear, welcome to the list and good to know that you are 
well and still operational.

You may be right about UBV photon counting and you the last left.  My last 
PMT observations were back in 1998 or so, the results from which were 
published in December 2004!

I am keeping my PMT photometers for old-time sake - they are also the best 
detector for very bright stars, which you never know may be all that's left 
over in the heavens as targets for we amateurs once the telescopes like 
Pan-STARRS and LSST start up.  Like you say also about the U-band, that is 
another avenue that PMTs work well in compared to CCDs.

> FWIW, I recently has some problems with the tracking on my old orange C-8 
> and purchased a new Meade LX-90 just before Christmas while it was on 
> sale. The LX-90 is a great telescope and I love the computer control, 
> however when I replace the C-8 with the LX-90 and did some UBV photometry 
> I was disappointed. The U band reading on the same star, same air mass 
> under similar skies is about half that of the C-8.

Could be a combination of things - more absorption by the corrector plate 
glass, UV transmission suffering if multicoating is optimised for the 
visible, etc.  Stay with the C-8.  I'm back to using my 24-year-old C-11 
tube assembly, it's a great scope.

> I'd be interested in hearing from anyone who is doing UBV photon counting. 
> I know equipment for that is hard to find, but really pretty easy to make. 
> I designed and marketed a unit back in the 1980's and have another design 
> I have been toying with.
>

I remember it well - personally I went for DC amplification rather than 
photon counting to avoid pulse pile-up problems with bright objects.  The 
brightest comparison 'star' I once used was Saturn.

Seriously - a key question is whether there could be certain astronomical 
projects out there, where your UBV photometer has a very distinct advantage 
over CCDs.  Not sure what the answer is??

Best regards,
Richard Miles