Per Dreyer, NGC 650 (= Méchain, Messier 76, 1860 RA 01 33 31, NPD 39 08.3) is "very bright, western of double nebula". The position precesses to RA 01 42 17.7, Dec +51 34 16, which is dead on the southern portion of the nebula, so the identification is certain. (There is no doubt that what Méchain and Messier observed was the entire nebula; but see NGC 651 for a discussion of the double listing.) This is one of many Messier objects for which Messier was not the discoverer, but merely a recorder of discoveries by others (Méchain was not only a colleague but also a close friend, as well as being one of Messier's most frequent contributors.)

Per Dreyer, NGC 651 (= John Herschel's GC 386, 1860 RA 01 33 34, NPD 39 07.7) is "very bright, eastern of double nebula". The position precesses to RA 01 42 20.8, Dec +51 34 52, which is dead on the northern portion of the nebula, so the identification is certain. There is no doubt that what Méchain and Messier observed was the entire nebula; but Herschel noticed that the nebula consisted of two brighter regions, slightly separated by a fainter middle, hence Dreyer's assignment of two numbers to the object. Since it is, as shown in the image below, a "bipolar" planetary nebula, that isn't entirely unreasonable; but normally such an object would be given only a single listing, so it is a little confusing, particularly since the normal way of describing the situation is to say that NGC 650 = NGC 651. A more accurate way, used above, is to keep the two listings separate, but say that M76 consists of both NGC objects (as is the case for several other Messier objects). This is one of many Messier objects for which Messier was not the discoverer, but merely a recorder of discoveries by others (Méchain was not only a colleague but also a close friend, as well as being one of Messier's most frequent contributors.) See NGC 650 for images and a physical discussion of the nebula.

(See IC 165 for a discussion of the double listing.) Based on recessional velocity of 3535 km/sec, about 155 million light years away, in good agreement with redshift-independent distance estimates of 125 to 155 million light years. Given that and apparent size of 3.2 by 0.6 arcmin, about 150 thousand light years across.