Re: Calculation of mag errors

[droege@snapmail.us]

Andrew Bennett writes:

> Another reason for keeping raw data ...

I hope to be more organized this year.  Rob's code allows me to do darks
every night.  I think I don't want to make flats every night.  I will
figure out a storage scheme to keep the current flat set with the data.

Thus I might as well keep the raw data.  But note that it is not very nice
to look at, so perhaps we should keep the processed data and the darks and
flats and have a way to reverse back to the raw image.

I really don't want to keep both.

Tom Droege

> On Thu, 3 Mar 2005 17:27:30 -0500, Stupendous Man
> <richmond@stupendous.cis.rit.edu> wrote:
>
>> ...
>>  Hmmm.  Before this week, I would have told someone to ignore
>>the uncertainty values for _most_ purposes.  Now, I would tell
>>someone to ignore them for _all_ purposes.
>
> Now I can dig out the Ensemble photometry
> code I put away in disgust a year ago. It was
> trying to do a proper error budget on the assumption
> that the photon noise was calculated right in the
> Database. All the unwanted variance got thrown
> into a catchall "image noise" term that got applied to
> all stars on an image. Underestimation of the photon
> noise causes the other noise terms to be systematically
> and hugely overestimated. The resulting large "errors"
> led to the  bright stars being weighted down by huge
> factors  compared to what they should have been, doing
> the fit no good at all.
>
> Another reason for keeping raw data ...
>
> Andrew Bennett, Avondale Vineyard, NS, Canada
>
>
>