NGC 7042 in Pegasus

August 2019 - Galaxy of the Month

August sees the return of astronomical dark to UK skies and also sees the 100th GOM. I can’t believe that so many of these have been written, almost 40000 words.

For this occasion, I have chosen the galaxy pair NGC 7042/7043 in Pegasus. This may feel like an inauspicious choice for such a landmark column but it is getting progressively more difficult to find interesting objects that fit within reach of medium sized telescopes.

NGC 7042 itself was discovered by William Herschel in 1784, but it took Albert Marth using William Lassell’s 48” speculum metal reflector to discover NGC 7043 in 1863.

Both galaxies appear to be face on spirals and appear to be a physical pair. They both appear to be part of an 11 galaxy group designated as LGG 442. This group also contains the galaxies NGC 7015 and NGC 7025 as well as a number of UGC galaxies.

NGC 7042/42 may be of the order of 210 million light years away, which would make NGC 7042 perhaps 110000 light years in diameter and NGC 7043 perhaps 70000 light years in diameter. Despite being physically associated NGC 7042 and NGC 7043 do not show any signs of tidal interactions.

As both the discoverers described their respective objects as faint it is perhaps not surprising that they do not appear in any of the standard references such as the Night Sky Observer's Guide (NSOG) or Luginbuhl and Skiff (L&S). NGC 7042 does however make the H400 II observing program, which admittedly is mostly non-descript galaxies. NGC 7042 was also home to the Type Ia supernova SN 2013fw.

Perhaps unsurprisingly given their nature there is not a lot of information in the research literature on either of these two galaxies as they would appear to be just run of the mill spirals.

Visually NGC 7042 itself would appear to be visible in a 14” (32-cm) telescope but only as a faint glow. I am not sure what size telescope is needed to see NGC 7043, although I have seen an observation of it which suggests that with averted vision it may be visible in 30-cm, although I would think this observation may be questionable. NGC 7043 has a listed magnitude of 14.8B which suggest that it is probably around 14th magnitude in V. The tightness of the pair would suggest that high power can be used on them and keep both galaxies still in the field of view.

Owen Brazell - Galaxy Section Director