Sh2-177 is an emission nebula in the constellation of Cassiopeia.
The cloud is identified few arcminutes southwest of κ Cassiopeiae, a star of magnitude 4.17 clearly
identifiable even under dark skies not perfectly, the structure nebula appears very weak and is revealed
in long-exposure photos taken with a powerful telescope amateur with appropriate filters. Its
declination is strongly northern, so it can be seen especially from the regions of the northern
hemisphere, where it occurs circumpolar to the more temperate latitudes lower, from the southern
hemisphere on the contrary his observation is limited to tropical regions.
It is a weak but extended H II region with a diameter of about 4.9 light-years, extended over a
very rich star field and part of the Perseus Arm, at about 2500 parsecs (about 8,150 years light)
away, at OB association Cassiopeia OB5, this association are related to some other open clusters
and nebulae smaller but more brilliant, as Sh2-172 and Sh2-173. the combined action of
the stellar wind of the stars large mass in the region of the association has created a large
super-bubble diameter of 380 parsecs. the main responsible for the ionization of the gas is a
blue star of spectral type 09V, cataloged as BD +61105.