Astronomy Picture of the Day 5-24-03

Explanation: If not perfect, then this spiral galaxy is at least one of the most photogenic. An island universe of about 100 billion stars, 30 million light-years away toward the constellation Pisces, NGC 628 or M74 presents a gorgeous face-on view to earthbound astronomers. Classified as an Sc galaxy, the grand design of M74's graceful spiral arms traced by bright blue star clusters and dark cosmic dust lanes, is similar in many respects to our own home galaxy, the Milky Way. Recorded with a 28 million pixel detector array, this impressive image celebrated first light for the Gemini Multi-Object Spectrograph (GMOS), a state-of-the-art instrument operational at the 8-meter Gemini North telescope. The Gemini North Observatory gazes into the skies above Mauna Kea, Hawaii, USA, while its twin observatory, Gemini South, operates from Cerro Pachón in central Chile.

Here is a finder chart for M74:

Right Ascension	01 : 36.7 (h:m)
Declination	+15 : 47 (deg:m)
Distance	35000 (kly)
Visual Brightness	9.4 (mag)
Apparent Dimension	10.2x9.5 (arc min)

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. (Eta Piscium is the most prominent star on the chart).

It may be difficult to find M74 under the slightest light pollution 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.

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.

Amateur image of M74.

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