NGC 6207 in Hercules

July 2025 - Galaxy of the Month

My target this month is the bright galaxy NGC 6207 in Hercules. It was discovered by William Herschel in 1787 and is better known because of its location as it lies about half a degree NE of the globular cluster M13. It is thought to lie at about 30 million light-years from us.

NGC 6207 is classified a SA(s)c spiral and if at the calculated distance is correct then it would be about 34,000 light-years across, so quite a small galaxy, about a third of the size of our Milky Way. There do seem to be a number of large blue star clusters in its spiral arms which suggests that there is ongoing star formation. NGC 6207 appears to be a fairly isolated galaxy however so it is not clear what is triggering the star formation episode. Deep images however suggest there may be five dwarf galaxies in the field and there could be interactions with those.

There are suggestions that NGC 6207 is part of one of the filaments of galaxies associated with the Virgo cluster, although it lies well in the foreground of that cluster which lies at a distance of about 55 million light-years. It may also be part of the Draco cloud of galaxies.

As seen in the Hubble Space Telescope images on Wikipedia, NGC 6207 shows well-defined spiral arms but interestingly there is not really a prominent nucleus. There is a star not far from the nucleus but this is part of our galaxy. NGC 6207 was also host to SN 2004A which was suspected to be a Type IIP event, i.e. a core collapse supernova.

The skies of July as seen from the northern climes of the UK are still bright so seeing any galaxies is a challenge but if this one is too easy for you then try for the much more challenging galaxy IC 4617 which lies half way between NGC 6207 and M13.

NGC 6207 is relatively small so it is best seen using medium to high power eyepieces. It is bright enough to be seen with small telescopes in the 20cm range from very dark sites even as small as 130mm. The Webb Deep-Sky Society Observer's Handbook Volume 4 has observations of NGC 6207 with instruments ranging in size from 15cm to 40cm and suggests that in the smaller instruments it appears as a grey uniform streak but some subtle details appear at 40cm. The galaxy is a part of many observing lists including the Astronomical League's H400 list of the 400 best objects discovered by William Herschel. It also features in Stephen O’Meara’s book The Secret Deep.

Owen Brazell - Galaxy Section Director