Re: Magnitude range of images

[Tom Droege <tdroege@veriomail.com>]

Michael's comments below are close.  The present data is a little better 
(always, I hope) and the repeated measurements offer the possibility of 
decreasing the error without affecting the saturation level.   The present 
exposures are 100 seconds which should hurt the saturation end and improve 
the faint end of the range.

Tom Droege

At 01:18 PM 10/22/01 -0400, you wrote:

   Dirk asks:

 > Those of you who have reduced Tom's images, what do you estimate the
 > useful range of magnitudes is in the V frames?  ...
 > .... By "useful" I mean the range over which we can hope to
 > measure the brightness of a variable to +/-5% at the faint end.

   Look at Tech Notes 75, 76, and 77

      http://a188-l009.rit.edu/tass/technotes/tn0075.html
      http://a188-l009.rit.edu/tass/technotes/tn0076.html
      http://a188-l009.rit.edu/tass/technotes/tn0077.html

where you can find three independent analyses of Mark IV data.

   An executive summary might be that for exposures of 50 second
in Batavia, photometry reaches the +/- 5% point around V = 12.5,
and saturation occurs around V = 8.0, I = 7.5.  But Andrew Bennett
and Jure Skvarc (and others, of course) should chime in if I've
misrepresented their results.

                                                Michael Richmond