FreeLists / az-observing / [AZ-Observing] Visual Limit From Sentinel Last Night

[Tom Polakis <polakis@xxxxxxx>]

Well, it wasn't so good at Sentinel for much of last night.  I crashed in
the back of my truck around 1:00, and while the sky was significantly
better than my back yard, transparency was still plagued by very thin
cirrus.  I awoke at 4:30 to excellent transparency, and looked around for
an hour, never rising from my mattress.  The walls of the truck bed blocked
the horizon glows, and I couldn't have been much more comfortable.  I think
this was important in seeing faint.

This was a good chance to do a "blind" test of magnitude limit.  I tried
two fields.  One was inside of the four bright stars of Corvus.  There, I
could just see a pair of equally bright stars north of the center of the
asterism.  They are HD 107879 and HD 107892, with Hipparcos magnitudes of
7.45 and 7.44, respectively.  I moved to the line between Alpha and Beta
Canes Venaticorum, and spotted HD 110392, which is listed in Hipparcos as
magnitude 7.60.  None of these three stars were easy to see, but they were
all definitely there over half of the time.  I don't doubt postings by
experienced observers with sharper vision than mine of limiting magnitudes
beyond 8.0.

Tom

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Tom Polakis
Tempe, AZ
Arizona Sky Pages
http://www.psiaz.com/polakis/
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