From: "Mel Bartels" 
To: 
Cc: 
Reply-To: "Mel Bartels" 


Bill Ferris is looking for observations of globular clusters to rank their
visibility with a variety of apertures and sky conditions.  The spreadsheet
is at

www.efn.org/~mbartels/aa/gcvis.xls

By receiving visibility rankings of these globulars, we will test current
theory and formulae.  It always remains a possibility that the current
model will need modification or replacement.

The list is geared towards a northern latitude of 40 degrees for this
August as it includes an extinction factor for objects close to the
horizon. The factor can easily be removed from the spreadsheet.  Both MS
Office and OpenOffice can view the file, so the spreadsheet should be
available to Win/Linux/Mac platforms.

If you can bin the gobulars into say 10 categories of most visible to
hardest to see, that would be fine.  Also give aperture and sky
transparency (say, estimation of dimmest star visible to 1/2 magnitude).

Mel Bartels

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