[Aavso-photometry] ST8-ST9-ST10

[Michael Sallman]

Gary and all,

There is also a similar calculator online here:
http://www.tass-survey.org/richmond/signal.shtml

Mike SVI

BailyHill at aol.com wrote:
> Hello;
>  
> Been lurking for the referenced discussion.  Had 2 experiences that I  wanted 
> to share.
>  
> Went to NEAF this year with the idea of upgrading from my ST10  camera.  
> Talked to several manufacturers and found one that had a camera  with back 
> illuminated E2V chip, super cooling, very low read noise,  extraordinary a/d 
> converter---etc.  Came away thinking I would buy  one.  The fact that I had just sold 
> a piece of equipment and had cash in  hand, made the argument even more 
> compelling.
>  
> Had a discussion with Arne at the MMO (Maria Mitchell Obs) opening to  
> celebrate their new 24 inch RC.  Arne and I did some ratios, extrapolating,  etc, 
> and came to the conclusion that the new hot camera would not necessarily be  a 
> miracle for reducing the errors.  However, aperture seemed like it might  be a 
> big winner.
>  
> So I dug out an old Sky and Tel article, Feb 93, by Sinnott and Mallama,  
> where they had a Basic Program to calculate the SN of a Telescope and  Camera.  
> The program took aperture, FWHM, sky background, read noise, dark  current, 
> scope focal length, & pixel size into account.  I converted it  to a spreadsheet, 
> expanded the program to include binning, QE of the chip, and  filter 
> throughput.  Now I could compare various scenarios.
>  
> Arne was right-what's new-the cameras make a small difference.   Aperture 
> makes a large difference.  
>  
> So I decided to run the numbers for the ST8, ST9, thru my ST10 in for  
> comparison.  For a 10 inch telescope, with 2500 mm focal length, 20 mag/arc  sec 
> squared skies, all binned 1x1, Imaging a 15 magnitude star, with fwhm of 3  arc 
> seconds;  the following SN ratios were calculated.
>  
> ST8 = 25;     ST9 = 27       ST10 = 32
>  
>  
> If we 2x2 so we have 18 and 13.6 micron pixels respectively; we get
>  
> ST8 = 32      ST10 = 46
>  
>  
> and if we bin 3x3 so we have 20.4 micron pixels; we get
>  
> ST10 = 52
>  
>  
> So no miracles, but a quantifiable result.  I have checked at  least the ST10 
> results with what I get on my 12 inch telescope, and it seems to  be close.
>  
>  
> Epitaph:   Well the big Winner from the NEAF show was the 20 and  24 inch 
> scopes.  As an example, the above scenario with the ST10 with a 20  inch jumps 
> the SN from 52 to 112---Wow a big difference.  Unfortunately the  cost of the 
> new tube is much more than the new camera, so I am sitting in  somewhat of a 
> dilemma.  
>  
>  
> Clear Skies
> Foggy in Nantucket
>  
> Gary
>  
>  
>  
> 
> 
> 
> ************************************** See what's free at http://www.aol.com.
> _______________________________________________
> 
> Aavso-photometry mailing list
> Aavso-photometry at mira.aavso.org
> http://www.aavso.org/mailman/listinfo/aavso-photometry
>