NGC 6278 in Hercules
August 2025 - Galaxy of the Month
With darker skies coming back in August we can start to look for fainter galaxies again. My choice this month is the galaxy pair NGC 6278 and NGC 6277 (6276) in Hercules. NGC 6278 was discovered by William Herschel in 1784 and independently again by Stephan in 1871. William described it as very faint so it might be a challenge. NGC 6277 was discovered by Marth in 1871 so it is going to be a challenge.
NGC 6278 is classified as a lenticular galaxy of type S0 lying perhaps 113 million light-years from us. Interestingly NGC 6277 is also classified as an S0 lenticular. NGC 6278, NGC 6277 along with UGC 10650 are contained in the poor galaxy group WBL 629, they are also included in the group LGG 409, both groups only containing these three galaxies.
As is often the case with faint galaxies discovered in the heyday of visual observing there is some confusion over the NGC numbers in this group. William Herschel’s discovery, NGC 6278, is secure but both Marth and Stephan found two objects here and they were given the designations NGC 6276 and NGC 6277. There is really only one galaxy here. It is probable that the galaxy identified as NGC 6277 is really NGC 6276 and NGC 6277 is really a star. What fun. Harold Corwin has this discussion in his NGC notes. Due to this confusion you may find the smaller galaxy named as either NGC 6277 or 6726 depending on how the charting makers treat the historically corrected NGC.
A deep imaging survey around NGC 6278 suggests that it is surrounded by 9 smaller satellite galaxies. If NGC 6278 is at the distances quoted then it is perhaps 82,000 light-years in diameter, so a little smaller than our Milky Way.
Recent studies suggest that this small grouping is also part of the filaments of galaxies associated with the Virgo cluster. There maybe 13 or so different filaments here as extracted from galaxy surveys. These filaments maybe several megaparsecs long. The group is also suspected of being a fossil group where many mergers have taken place and the group is now just the remnants of what was there.
The two NGC galaxies are fairly close together so they will fit in the same field of view in a high power eyepiece and this will probably be the best way to see them. The third member of the group, UGC 10650, is also close by in the same high power field as the other two but is probably too faint to be seen in any but the largest amateur telescopes. I note that these galaxies may well be challenging to see as Steve Gottlieb in his NGC notes describes them as faint in a 17.5” telescope.
Owen Brazell - Galaxy Section Director
