[Aavso-photometry] Uncertainty

[Arne Henden]

On 11/19/07, Richard Harvan <tkdvarstar at yahoo.com> wrote:
> Dear All,
>           I would like to get your opinion on my calculation of uncertainty.  The procedure I am writing about calculates the standard deviation of the variable and the check star.  These values are then combined in quadrature with the stated uncertainty of the photometry of the comp star and check star.  Is this a reasonable method or am I going overboard.
>                     I saw in a textbook that the uncertainty of an average was the standard deviation divided by the square root of the sample size.  When I applied this to my data the calculated value was much less than the stated uncertainty.  This seemed too good to be true, so I have doubts about applying this to my measurements.  What is your opinion?
>   Thanks for your help in advance.
>
I'm a bit confused, so I need more information.  My assumption from above is:
(1) you take a series of images
(2) you aperture-photometer the variable, the comparison, and the
check on all frames.
Then what steps are you taking?  I don't understand "standard
deviation of the variable
and the check star."   I can understand standard deviation of (K-C).
Arne