[Aavso-photometry] Baseline photometry of HD 74156 at CBA BelgiumObservatory - results

[Tonny Vanmunster]

Hi Radu,

> Do you know what causes the up-slope?

No, I don't have a good explanation for the up slope. I started through tick
air-mass (low altitude), so that might have had some effect ? 

> I'm not sure stopping down is the best strategy: say you stop down to 1/3
aperture. You can then 
> expose each frame 9 times longer, and get factor of three improvment in
scintillation noise due 
> to that. But the reduced aperture will increase scintillation by a factor
of about 2. 
> So your total gain is only about 1.5 times. OTOH, if in the same time you
would have taken 4 
> short-exposure frames and averaged them together, you would have gotten a
factor of 2 improvment 
> (and i think you can get even more short exposure frames, depending on the
camera's download time).

> I think you can gain more by using an ND filter (or just use B instead of
V) and/or slightly defocus the stars.

I will definitely do some experimenting with the defocusing too.

Best regards,
Tonny

> 
> Best regards,
> Tonny
> 
> Tonny Vanmunster
> CBA Belgium Observatory
> http://www.cbabelgium.com
> ________________________________________________________
> PERANSO : The Final Frontier of Period Analysis Software 
> http://www.peranso.com 
> ________________________________________________________
>  
> 
> 
> _______________________________________________
> Aavso-photometry mailing list
> Aavso-photometry at mira.aavso.org
> http://www.aavso.org/mailman/listinfo/aavso-photometry
> 

-- 

-------------
Radu Corlan       Snail Mail: Bucuresti sect. 1, 
rcorlan at pcnet.ro  str. Argentina nr. 28, Romania

   You can still escape the "Gates" of Hell!   
                 Use Linux!                       


_______________________________________________
Aavso-photometry mailing list
Aavso-photometry at mira.aavso.org
http://www.aavso.org/mailman/listinfo/aavso-photometry