[Aavso-photometry] In defense of the ST-9 & CCD choice Considerations

[Michael Newberry]

If CCDU makes such statements, then I would kindly suggest that Apogee's 
website is not giving the best advice. To my knowledge, no one at Apogee is 
an astronomer. Arne and I (and others) have "been there and done that" for a 
lot of years. Take Arne's advice!

Michael Newberry

----- Original Message ----- 
From: <mlfleenor at charter.net>
To: "AAVSO photometry" <aavso-photometry at aavso.org>; "arne" <arne at aavso.org>
Sent: Tuesday, June 12, 2007 8:45 AM
Subject: Re: [Aavso-photometry] In defense of the ST-9 & CCD choice 
Considerations


>
>
> Re: 2 arc-second/pix sky coverage  check out CCD Univeristy @ apogee's 
> website.
> http://www.ccd.com/ccd113.html
>
> In re-reading Tim’s post I see that he  said 2-3  pixel sky coverage not 
> 2. I was wanting to illustrate that as long as you are not running 
> under-sampled that this criterion was not something that has to be 
> explicitly followed.
>
> I use my SCT with a compressor and often run binned 2x2 yielding 1.24 
> arc-sec/pix resolution or ~ 2.4 pixel sky coverage- however many times I 
> am running 1x1 @ 0.62 arc-sec/pix  resulting in 5-6 pixel sky coverage 
> with my typical seeing. Clearly outside of the 2-3 pixel criterion yet my 
> results are excellent. ( I often achieve 1mmag precision with R-band 5 
> minute averages with extra-solar planet candidates during out of transit 
> baselines. )
>
> My frustration with the ST-9 was due in part to some of the images having 
> blocky stars- I was under-sampling! I also was running @ 2260mm focal 
> length. I could’ve run the SCT @ f/10 but here again the fov would be much 
> too small for me.
>
> I do take a slight sensitivity hit but also need the resolution to resolve 
> close stars.
> While the ST-9 may better meet the  magic sampling requirement there are 
> other considerations.
>
> I bet there are a lot more folks doing photometry with SCT’s using ST8’s 
> instead of ST-9’s .
>
> Mike
>
>
>
>
>
>
>
>> Mike, have you seriously found a recent posting or reference that
>> gives a guideline of 2arcsec/pix?
>> Arne
>
>
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