FreeLists / az-observing / [AZ-Observing] Re: Check Out These "Backyard" Images...

[Brian Skiff <Brian.Skiff@xxxxxxxxxx>]

     Looking at the Andromeda image, in a one-hour total exposure he's
getting down to about V=17 on stars, and mag. 23-24 per square arcsec
in surface brightness.  You'd need about a 16-inch from a dark site to
match the stellar limit visually, but only a 6-inch to match the rather
bright surface-brightness limit, the most obvious consequence of his
bright site.  Notice he's had to over-process the M31 image to get even
that (the dark moats around the star images are a tell-tale sign of
over-processing).
     Note also the labelling of the M31 clusters in the image contains
two errors, copied directly from 'Night Sky Observer's Guide':  the
cluster G87 near NGC 206 is actually G52, and G78 is mismarked, the cluster
being the brighter object immediately below at about 5 o'clock from the
thing that's marked.
     The emission-line composites "work" from the nominally bright site
beacuse he's observing with the narrow filters, and the nebular lines
are felicitously located in relatively dark regions of the spectrum
even at a (broadband) light-polluted site.  So he's taking advantage of
astrophysics as much as technology to get the results.

\Brian
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