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The constellation
of Cassiopeia is bursting with rich and colorful open clusters
begging to be captured with your sensors. A prime example NGC7789
is 6.7 magnitude, and over 15 arcminutes across. Containing over
250 stars, it is a moderately rich cluster complete with a good
selection of orange and yellow supergiants, a good many of which
are variable stars.
This image readily demonstrates
the image quality I can obtain with my f/5 Newtonian and a focal
plane coma corrector. Examine the 1600 sized image if you dare,
stars and cluster details remain crisp right into the corners.
To the upper right,
near the top edge is a very red variable star WY cass. This
type M star varies in brightness over a 476 day period from 10th
to 17th magnitude and is considered a long period variable. It
shows up about half the time on my images over the years of this
object, and here we were lucky enough to capture it in a deep
red and fairly bright state.
Processing: Three five
minute subframes were dark subtracted, flat fielded and then
summed and aligned in Maxim DL. Absolutely NO additional noise
reduction was used here.
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