|Right Ascension||01 : 36.7 (h:m)
|Declination||+15 : 47 (deg:m)
|Visual Brightness||9.4 (mag)
|Apparent Dimension||10.2x9.5 (arc min)
Discovered 1780 by Pierre Méchain.
This conspicuous spiral is a prototype of a grand-design Sc galaxy. It is classified in more detail in De Vaucouleur's scheme as of type SA(s)c, i.e. a barless (therefore "SA") Sc spiral without a ring structure ("s"). Its distance may be about 30 to 40 million light years (R. Brent Tully's Nearby Galaxies Catalog has 32), as it recedes with 793 km/sec. Then its spiral arms are about 1000 light years broad. They are traced with clusters of blue young stars and pinkish colored diffuse gaseous nebulae (H II regions) in color photos, and reach out to cover a region of more than 10 minutes of arc in diameter, corresponding to roughly 95,000 light years, or about the same size as our Milky Way galaxy. The Webb Society Deep-Sky Observer's Handbook gives a number of 193 known H II regions. The nucleus of Sc spiral galaxy M74 is small and bright.
M74 is probably the chief member of a very small physical group of galaxies, which includes the peculiar SBa barred spiral NGC 660, the peculiar Sm galaxy UGC 891 (of a mixed type between spirals and irregulars), and the irregulars UGC 1176, UGC 1195, and UGCA 20.
For the amateur, very good conditions are needed to see more than this nucleus. But if they are given, suggestions of the magnificient spiral arms become apparent in telescopes starting at 4-inch. In telescopes of this size, the nucleus appears quite sharply limited, the diffuse hazy and mottled disk around it can be traced to a diameter of about 6' to 8'. Numerous faint foreground stars are visible in the field around this galaxy. Larger telescopes show the faint spiral arms more and more clearly, and in large amateur instruments (16-inch up), knots become recognizable within and between the spiral arms, which are foreground stars as well as star clouds and nebulae within M74's disk.
M74 can be found easiest from Hamal (Alpha Arietis); from this star, follow a line via Beta Arietis to Eta Piscium (mag 3.5); M74 is about 1/2 deg N and 1 1/2 deg E of Eta Psc; this route is also particularly well suited in Messier Marathons.
It may be difficult to find M74 under the slightest light polution or other imperfect viewing conditions, as its nucleus is almost stellar, and the disk and spiral arms of considerable low surface brightness. It may help to locate the pair of 6th-mag stars, 103 and 105 Piscium, about 1 deg NE of M74, and look up a pair of 10th mag stars, about 3' apart and oriented N--S; M74 is about 6' West of this pair.
The nearby star Eta Piscium is a double: A, 3.7 mag; B, 11.0 mag; position angle (PA) 19deg, separation 1.0".
Messier marathoners often miss this galaxy in the evening, as it stands near the border of the "Messier-Free Zone" in the sky. Only globular cluster M30 is missed more frequently than this galaxy.
The almost stellar nucleus has been erroneously cataloged as a star in the "Bonner Durchmusterung" by F.W. Argelander in 1860, under the designation BD +15deg 238.
Last Modification: 9 Dec 1999, 22:58 MET