Cepheus near the border with Cygnus. Bright Moonlight causing some background gradients.
NGC 6939, discovered by William Herschel of course, is quite old for an Open Cluster, between 1 and 1.3 billion years. It also lies about 400 parsecs above the galactic plane, a little unusual for Open Clusters as they are usually within the plane of the galaxy, hence the alternative name of Galactic Clusters.
NGC 6946 (also discovered by William Herschel) is about 25 million light years away and resides in the Virgo Supercluster. It’s known as the Fireworks Galaxy because it seems to be a hive of supernovae; ten have been observed in the 20th and 21st centuries alone. This is about 10 times the rate observed in our own galaxy, even though the Milky Way has twice as many stars. In fact more supernovae have been observed in this galaxy than any other.
During 2009, a bright star within NGC 6946 flared up over several months to become over one million times as bright as the Sun. Shortly thereafter it faded rapidly. Observations with the Hubble Space Telescope suggest that the star did not survive, although there remains some infrared emission from its position. This is thought to come from debris falling onto a black hole that formed when the star died. This potential black hole-forming star is designated N6946-BH1. The progenitor is believed to have been a yellow hypergiant star. Wikipedia
Stephan’s Quintet is to the left, consisting of 4 related galaxies and NGC 7320 which is a foreground galaxy. Their brightness’s range from +14.6 to +15.7. NGC 7318B is colliding with gas in the group, producing a huge shock wave bigger than the Milky Way, spreading through the medium between the galaxies, heating the gas to millions of degrees, emitting X-rays. A sixth galaxy, NGC 7320C appears to be connected by a tidal tail (just visible) to NGC 7319.
NGC 7331 or Caldwell 30 (to the right) is similar in size and structure to the Milky Way, 40M light years away. A discovery by William Herschel in 1784. It is the main body in the NGC 7331 Group, which contains unbarred spirals NGC 7335 and 7336, the barred spiral galaxy NGC 7337 and the elliptical galaxy NGC 7340. These other galaxies are all much further away (~300M ly), so not related to NGC 7331.
Added more data to this one but still very tricky. More horrible gradients to deal with. The IDAS P2 LP filter is no longer doing it’s job with the change in LP sources round here. Have now bought the IDAS D3 to see if that is any better as it deals more with LED lighting.
Another go a this for the ASE Caldwell Project. A really tricky one this. Hidden in the dust from our own galaxy, this would actually be naked eye brightness if not obscured. From two sets of data but still challenging.