NGC 7788 and 7790 are two small open clusters
in the constellation Cassiopeia, at distances of about 8,000 and
10,000 light-years respectively. NGC 7790 is at the top center
and NGC 7788 is to the lower right. The beautiful bright copper
colored star, to the left center, at magnitude 6.63 is SAO
20954.NGC 7790 is astronomically important because it contains
three Cepheid variable stars. These three Cepheids are useful
for determining a zero point distance for this special type of
star. Cepheid variables are used to determine galactic
distances.
