[Aavso-photometry] Re: CCDs vs. Single-channel Photometry

[Jeff Hopkins]

Hello Richard,

I sometimes forget that other observers do not have the Arizona 
skies. I'm probably very spoiled. One of these days when finances 
allow I may give CCD photometry a try again. I tried it a while back 
with a mid-range Meade CCD camera. It was a total disaster, probably 
because I did not know what I was doing. I ended up selling the 
camera for half of what I paid for it. This was several years ago 
and I suspect new cameras are now cheaper and better along with the 
software.

Jeff

At 14:58 -0700 1/25/05, Richard Miles wrote:
>Jeff Hopkins wrote:
>>  While determination of the sky condition could warrant 
>>determination of standard deviations of comparison stars, for 
>>normal work, I do not think that necessary.....
>>Aside as noted above, doing standard deviations on the comparison 
>>stars is rather meaningless as the whole point is determining the 
>>program star magnitude.
>
>===>  Jeff, I think you and Michael are talking at cross-purposes 
>somewhat; Michael is specifically referring to how it's best done 
>using CCDs whereas single-channel PMT-based photometry is as how you 
>describe.  The two techniques are very different and have different 
>strengths and weaknesses.
>
>>
>>  I'm truly surprised there are not more people doing single channel 
>>photometry, particularly photon counting. It is certainly much 
>>easier, much cheaper and appears to be more accurate. I'd be happy 
>>to help anyone interested in pursuing that.
>>
>
>===>  Your offer is noted, thanks.  I hope one or two people on this 
>list do take up your offer.
>
>===>  May I just add one thought to highlight an important 
>consideration though.  What you write is quite true and is typical 
>where you have very good skies in terms of constancy of transparency 
>as is the case for most of Arizona for a good proportion of the 
>months in the year.  However, as is the case in the U.K., where the 
>sky conditions are often very poor, CCDs offer the great advantage 
>of being able to cut through most of the sky variability, within 
>limits, so that accurate differential mags can be secured even under 
>relatively adverse conditions - using a single-channel detector 
>would be hopeless in such conditions.
>
>===>  So a word of warning to 'would-be' single-channel 
>photometricists, if you are frequently treated to superb skies then 
>by all means get a single-channel photometer and you will be able to 
>do some great observing. However, if photometrically-clear skies 
>only appear once or twice a month, then stick with your CCD.
>
>Richard Miles
>
>P.S.  One other strength of single-channel photometry - The data 
>reduction process is vastly more straightforward and it's great to 
>get your results virtually in real-time.  This is my biggest issue 
>with CCDs at present.

-- 
Jeff Hopkins
HPO SOFT
http://www.hposoft.com/Astro/astro.html

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