Discovered: Possibly 1654 by the Italian astronomer Giovanni Battista Hodierna, Observed and cataloged on August 25, 1764 by French Astronomer Charles Messier. [1][2]

Object Type: Spiral Galaxy [3]

Apparent Magnitude: 5.7 [3]

Distance: ~3 million light-years away [3]

Other Designations: NGC 598, UGC 1117, PGC 5818 [4]

Constellation: Triangulum [3]

Notes from Messier:

August 25, 1764. 33. 1h 40m 37s (20d 09' 17") +29d 32' 25"
Nebula discovered between the head of the Northern Fish [of Pisces] & the great Triangle, a bit distant from a star of 6th magnitude: The nebula is of a whitish light of almost even density [of brightness], however a little brighter along two-third of its diameter, & contains no star. One sees it with difficulty with an ordinary telescope of 1-foot [FL]. Its position was determined from Alpha Trianguli. Seen again September 27, 1780. (diam. 15') [2]

[Mem. Acad. for 1771, p. 448 (first Messier catalog)]
In the night of August 25 to 26, 1764, I have discovered a nebula between the head of the northern Fish [of Pisces] & the large Triangle [Triangulum], a bit distant from a star whioch had not been known, of sixth magnitude, of which I have determined the position; the right ascension of that star was 22d 7' 13", & its declination 29d 54' 10" north: near that star, there is another one which is the first of Triangulum, described by the letter b. Flamsteed described it in his catalog, of sixth magnitude; it is less beautiful than that of which I have given the position, & one should set it to the rank of the stars of the eighth class [magnitude]. The nebula is a whitish light of 15 minutes in diameter, of an almost even density, despite a bit more luminous at two third of its diameter; it doesn't contain any star: one sees it with difficulty with an ordinary [non-achromatic] refractor of one foot [FL]. I have compared it to the star Alpha Trianguli, & with that of which I have reported the position. I have found the right ascension of that nebula at 20d 9' 17", & its declination of 29d 32' 25" north. [p. 457] 1764.Aug.25. RA: 20. 9.17, Dec: 29.32.25.B, Diam: 0.15. Nebula without stars, between the head of the northern Fish [of Pisces] & the great Triangle, it has little distance from a new star of 6th magnitude & the star b Trianguli, according to Flamsteed. [2]