News from Rochester

[Stupendous Man <richmond@a188-l009.rit.edu>]

  Tonight I am going to let the Mark IV run all night, sitting
on the equator and watching the sky go past.  I get 3 to 5 measurements
of each star over a period of 15-25 minutes.  There are bound to be
lots of stars with good photometry (Landolt, etc.) on the standard
system.  I'm going to see how well I can calibrate the cameras.

  It's not going to be easy, because even a little layer of cloud
will cause the photometric calibration to change from one field
to another.  One test I plan to make is to reduce the data in two
ways:

         a) one field at a time, differentially against Tycho stars
                 (using Bt and Vt converted to V, I)

         b) standard all-sky photometry, using Landolt (and other)
                 standards as they occur


  I'll probably learn something about the system by comparing the
results of these two different methods.  

  Hmm.  Since I'm looking at the equator, I suppose I can _also_ 
try reducing the data against the Mark III "tenxcat" magnitudes.
Those were calibrated directly against Landolt stars, too.  Yes, 
using Landolt stars alone would be better .... if the skies here
were clear.  But if the skies _aren't_ clear, a field-by-field
approach may be better.

  In any case, that will be my plan for the next while.  I have
a heavy teaching load this quarter, so I won't be able to gather
nearly as much data as Tom, nor reduce that which I gather so 
promptly.  I'll just do what I can to see how well we can
address the concerns that Brian mentioned.

                                           Michael