NGC 7331 is an excellent spiral galaxy mendacity in northern Pegasus, one of many brightest seen within the autumn sky, which will be present in apertures as small as 60–80mm (~three inches). It’s a high-quality sight by means of a moderate-aperture telescope, trying like a miniature model of mighty Messier 31 in Andromeda, and makes an irresistible imaging goal, with its dusty spiral arms giving up an enormous quantity of element.
There are fairly numerous implausible galaxies within the New Normal Catalogue (NGC) that haven’t been afforded ‘Messier’ standing. NGC 7331 is without doubt one of the only a few vying for the title of the very best non-Messier galaxy within the extra northerly reaches of the night time sky that Charles Messier, together with William Herschel, made his personal over 250 years in the past.
NGC 7331 shines at magnitude +10.3 and its inclined type spans a considerable 10.5’ x 3.7’. It’s an excellent spiral galaxy with a morphological classification of SA(s)b), in step with what we see as reasonably tightly-wound spiral arms and a scarcity of a central bar. It’s extremely inclined by 77 levels to our line of sight, which supplies us an indirect view of its majestic spiral arms. It’s believed that NGC 7331 spans round 100,000 gentle years and lies round 40 million gentle years away.
There’s no easy star-hop to seek out NGC 7331; strive beginning at Scheat (beta [β] Pegasi), the magnitude +2.4 star that marks the north-western nook of the well-known ‘Sq. of Pegasus’. From right here, transfer 5 levels west-north-west to land on magnitude +2.9 Matar (eta [η] Pegasi) after which sweep simply over 4 levels north-north-west. On early October nights NGC 7331 culminates at about 11pm BST, excessive overhead on the lofty heights of 70 levels or so.
NGC 7331 might be out of vary of a pair of 10 x 50 binoculars from UK shores, except you might be fortunate sufficient to be beneath an especially clear sky at a really darkish website. Nonetheless, solely marginally extra gentle grasp would bag it, as an 80mm telescope will present it as a small, fuzzy oval of sunshine spanning maybe 5 arcminutes.
A 150–200mm (six–eight-inch) telescope working at low to medium energy will reveal way more. Examine the galaxy for a while and a touch of its brighter core and an asymmetry – the core appears to lie off to 1 facet – ought to turn into obvious. House owners of bigger telescopes, say within the 250–300mm (10- to 12-inch) vary, ought to be capable to see a faint halo of nebulosity – the galaxy’s excellent spiral arms – and maybe a touch of a darkish lane working down its western flank.
Pictures and light-bucket Dobsonians reveal numerous smaller galaxies surrounding NGC 7331. The brighter examples all have NGC designations – 7333, 7335, 7337, 7338, 7336, 7325, 7327 and 7326. Together with NGC 7331 they’re referred to as the ‘Deer Lick Group’ or simply the ‘NGC 7331 group’. They aren’t bodily related to NGC 7331, as they lie six occasions additional away than the comparatively close by distance of fifty million gentle years attributed to the primary galaxy.
