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	Mon, 03 Apr 2006 14:45:15 PDT
Date: Mon, 3 Apr 2006 14:45:15 -0700 (PDT)
From: Tim Crawford <tcarchcape

From: "Stupendous_Mn" <mwrsps


> Date: 3 Apr 2006 13:50:14 -0000
       
>   Tim Crawford  wrote:
> 
> About a year ago I began, what for me was, a very
>  frustrating search for information on ensemble
> photometry.  I used both the NASA ADS search
> engine as well as the AAVSO's.  There were a number
of
> papers available regarding the topic of ensemble
> photometry but few that presented "method"
information in a
> way that the seemed to be readily understandable by
> the typical AAVSO CCD observer. 


Thanks very much to Tim for writing a very clear
various techniques for using comp stars compare to
each other.  I found his simple example with three
comp stars made the comparison easy to follow.

Readers who want to go into further detail on the
theory behind "ensemble photometry" would probably
find this paper by Kent Honeycutt a good place to
start.  

The brief reference is 

1992PASP..104..435H
 
and the following URL will take you to the ADS system,
from which you can click to a nice scanned version of
the entire text.


and are willing to tinker under the hood a bit might
want to look at

http://spiff.rit.edu/ensemble/
 
which provides an implementation of  Honeycutt's
method.  The idea in it is very much like the
"Weighted Average"  technique described in Tim's
paper.   It may not make sense to use this particular
software unless you wish to use lots and lots (ten?
twenty? eighty?) of comparison stars in a single
field.

 Thanks for the paper, Tim!

Michael Richmond




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