[Aavso-photometry] When to submit "Fainter Than" versus actualnumbers.

[BailyHill at aol.com]

Hello Jeff and All;

I started thinking about this, and had a couple of questions and comments.  

First, I use Maxim for software.  The way I understand it works, is that one 
designates a reference star in the image, and tells Maxim what value to assign 
to it.  So in the results, the Reference star always is defined with this 
value.

One then tells Maxim which star in the image is the "Object".  One also may 
designate several "Check Stars".  My understanding is that the "Object" and 
"Check" stars are measured, relative to the Reference Star.  So the "Object" and 
"Check" stars are not measured for absolute brighness, but are measured 
relative to the "Reference Star".

So when I do a time series, I have several check stars with their values 
measured relative to the "Ref star".  It seems to me that if these check stars are 
close in magnitude and color to the Object, that the Std Dev of the Check 
Stars gives a good representation of the total error of the Photometry Process.  

In fact, a recent run on BZ Uma at minimum, the 15.6, 16.3 and 17.0 Check 
Stars had Std Devs of .045, .056 and .066 respctively, for 95 measurements, over 
a 4 hour period.  BZ Uma had an average of 15.830 with a Std Dev .192.  It 
seems clear that BZ Uma was active that night.  

In that same run, the brighter check stars 13.1, 13.7 and 14.8 had Std Devs 
of .018, .024 and .017 respectively, for these 95 measurements of 2 minutes 
each.  

So if Maxim works as it is described in the manual,  I don't understand why 
the Std Dev is not the best representation of the process--assuming of course 
that the Check stars are not variable.

It would be interesting to hear how other software packages handle the time 
series measurement.


Clear Skies
Gary