[Aavso-photometry] Time series for GK Persei

[Walt Cooney]

Gianluca,

Tell us what your signal to noise ratio is too.  The best possible error 
that you can produce with everything else perfect is 1/(S/N).  Please 
clarify 13.13.27 as well.  That must be an entirely new magnitude 
system.  :-)

Clearest skies,
Walt

Jeff Hopkins wrote:
> Hi Gianiuca,
>
> I am not familiar with GK Persei, but you have a 0.08 magnitude 
> variation in less than 2 minutes, which is big and fast.  That would 
> be suspect.
>
> What I would do is make sure I was doing differential filter 
> photometry, take 3-20 second exposures and repeat every 10 minutes 
> for several tries. Then average each set of 3 and take a standard 
> deviation. Then look at all the sets and see if you see any 
> significant changes.
>
> The changes you see may be real, but without a more rigorous 
> approach, I would not trust them.
>
> Good luck.
>
> Jeff
>
> At 12:05 -0700 03/22/2008, gianlucaros at gmail.com wrote:
>   
>> I have experimented to take TS of GK Persei on Feb 24th to see if I
>> can detect the small fluctuations around minimum. I have actually
>> taken 5 consecutive exposures 20 sec each and done the calibration
>> with both darks and flats. Since I get 5 different mag value (13.19,
>> 13.23, 13.13.27,13.22,13.23) I wonder whether such measurements are
>> indication of the behaviour of the star rather than problems in
>> accuracy. Sorry for asking a question that could be trivial to answer.
>> Gianluca (RGN)
>>     
>
>