Sky Object of the Month – December 2016
(Courtesy LVAS Observer’s Challenge*)
M74 – Spiral Galaxy in Pisces (Mag. 9.4; Size 10’)
For backyard astronomers who tackle the annual Messier Marathon, M74 is a serious stumbling block. Even in December, when Pisces rides high in the south when evening darkness has set in, this face-on spiral galaxy is difficult to view. During Messier Marathon time in mid to late March, M74 is all but lost as it sets in the glow of evening twilight.
What makes M74 such a challenge is its low surface brightness. A 9th magnitude galaxy shouldn’t be difficult to observe, but when its light is spread over an area one-third the moon’s apparent diameter it becomes a phantom best saved for especially clear nights.
I’ve seen M74 in a 3-inch f/10 scope, but only with averted vision after knowing exactly where to look. A 3-inch f/6 rich-field scope captured both M74 and the 3.6 magnitude star eta (η) Piscium 1½ degrees to its west-southwest. In both instances, I worked with a magnification under 40X. To me, M74 was large and roundish – a smaller version of M33 and M101. Even when viewed with my 13.1-inch f/4.5 reflector, M74 was a vague glow.
M74 was discovered by Pierre Méchain in the autumn of 1780. It lies an estimated 33 million light years from earth.
Glenn Chaple for the LVAS
IAU and Sky and Telescope