Re: long term variation and instrumental drift

[Tom Droege <tdroege2@earthlink.net>]

Michael wonders below how bad the present reduction is.  I am an engineer 
by training and think of everything as a compromise and cost trade off.  I 
accept that I am running at a bad location.  So I don't expect to get the 
best possible photometry.  I leave that for Arne and the Mark IV at 
NOFS.  I would be content to get a lot of "pretty good" photometry.  This, 
I hope, may be good for one purpose while Arne's work is good for 
another.  If Arne's position is that less than perfect photometry is 
worthless, then I am willing to take the risk that someone will find my 
measurements useful.  There is a point at which you quit picking at every 
little detail and get the job done.  It does no good if we work so hard at 
calibrating something that cannot be calibrated very well that we never get 
a result.

It seems to me that the present reduction is pretty good.  It might be as 
good as is possible in my location.  So I am ready to get on with it and 
get a result.  Of course I can already see where improvements can be 
made.  Cloud rejection is one area.  I can see that cloudy nights have more 
scatter than clear nights.  I want to process a big set of data with some 
sort of cloud filter so that I can see the result on the scatter.  That is 
why I have been calling this an engineering run.  I fully expect to run the 
entire data set through the pipeline again before publication.  I hope that 
we can learn enough in the next several months to do it a lot better.  But 
then I plan to do it, and publish, and to make a lot more measurements and 
publish those.

Tom Droege

At 07:55 PM 6/9/02 -0400, you wrote:
>It's certainly dangerous to do a poor job of calibration, I admit.
>Is the current one really that bad?  :-(  As mentioned earlier,
>I hope to answer this question by the end of June in a TN...