[Aavso-photometry] Re: Aavso-photometry Digest, Vol 25, Issue 12

[Gianluca]

Hello Gary,
the size of the pixel is 7.4 microns in a 1600x1200 array. If this camera
turns out to be not good in combination with my scope, can you tell me which
of the other cameras currently on the market should I use for more accurate
photometry?
Clear skies
Gianluca

----- Original Message -----
From: <aavso-photometry-request at mira.aavso.org>
To: <aavso-photometry at mira.aavso.org>

> Hello Gianluca;
>
> Your should measure this on your camera and scope combintion.  Just take a
> star--say 12 mag or so, and expose it for 1,2, 3,4, .....seconds--until
the star
> blooms.   Since this is an antiblooming camera, this may not occur as
ususal.
>  Then plot the adu's of the star vs exposure time.  It should be  clear
where
> it deviates from linear by more than 1%.  Since this is an antiblooming
> camera I believe, the camera may not be linear above 1/2 full well.  This
is the
> only save way to do this.  It takes into account the version of your
camera, the
> software, etc.
>
> I observe from suburban Boston--probably not too different from Rome.  I
> rarely get below 2.5 arc secs FWHM.  Quite often the stars are more like
3-4 arc
> sec FWHM.  Under bad conditions, it goes to 5-6.  To properly sample for
> photometry, you need 2-3 pixels per FWHM.  This works out to an image
scale of 1 arc
> second per pixel.  I do not know the size of the pixels in this camera,
but
> with 800mm focal length, I do not think you are close.  Let me know the
pixel
> size and I can calculate it for you.
>
> Clear Skies
> Gary Walker
>
>
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> End of Aavso-photometry Digest, Vol 25, Issue 12
> ************************************************