Art Russell's Monthly Messier Star-Hop; February #2

Okay, so it’s the dead of winter. It really hasn’t been that cold has it? Certainly not enough to stop those of us who are slightly enamored of the stars and the deep-sky objects dwelling therein. Other than the clouds that always seem to plague us during winter, this is arguably the best time of year for observing because of low levels of humidity and suspended particulates (AKA: HAZE!) in the Southeast.

Star-Hop#1. Castor, Alpha (a ) Geminorum. Castor is one of the most interesting "double stars" under night skies. Amateur sized telescopes can easily separate the star into two components, Castor A and Castor B. There is another companion star, Castor C, but shining at magnitude 9.1 it is much harder to find. Moreover, each of these component stars is itself a double star as well, giving us a six-star system! Locating Castor is easy once you’ve identified the constellation. Shining at about magnitude 2, it is very prominent, and located to the about 4 degrees, or a little less than the width of three fingers, northwest of the brighter star Pollux. Remember how to find Castor, as it is our jumping off point for the rest of this month’s star-hops.

Star-Hop#2. NGC 2392, the Eskimo or Clown Face Nebula. Starting at Castor, locate the star Pollux to the southeast of Castor. From Pollux, extend a line southwest about 8 degrees, or the width of four fingers against the night sky, to the star Wasat, Delta, Geminorum. From Wasat, extend an imaginary line a little more than 2 degrees, or about twice the distance spanned by our little finger against the sky, to the southwest to the planetary nebula, NGC 2392. Although moderately faint, NGC 2392 is a relatively easy planetary nebula to find in moderate sized telescopes. At 259X and an OIII filter, the nebula appears evenly distributed around the central star. Although the nebula fades off rapidly at edges there is a hint of a ring structure. At 476X with an OIII filter the central star fades, there is a greater impression of a ring structure.

Star-Hop#3. M35, NGC 2168. Starting at Castor, we’ll next star-hop our way down the northern side of the constellation Gemini for our final star-hops. Extend a line about 5 degrees, or about the distance spanned by three fingers against the night sky, west-southwest, to the star Tau Geminorum. From there, continue the line a little less than 8 degrees, or the width of four fingers against the night sky, to the southwest and the star Epsilon Geminorum. From there, extend a line about 2 degrees, or twice the distance spanned by your little finger, west to the star Propus, Eta Geminorum. From Eta Geminorum, continue the line once again for about 2 degrees to the star 1 Geminorum. Remember where 1 Geminorum is located as it will be our base from which to locate all of our remaining deep-sky objects. From 1 Geminorum, M35 is located only about a degree and a half to the northeast. Here the open cluster, M35 dominates the scene. At 62X in a moderate sized telescope, M35 is well concentrated in a rich field of stars. Its structure is very distinct and also seems to have three point stars in center of the cluster.

Star-Hop#4. NGC 2158. NGC 2158 is prominently visible in the south-west corner of the same field of view as M35, but if you miss it, its very close by, only about a half-degree to the west-southwest M35. At moderate magnifications, NGC N2158 appears as a very soft irregularly shaped elongated body, gray-white in color. Some stars are visible in averted vision with 8 stars counted and concentrated in the center of the cluster. NGC N2158 is easy to find and appears well detached from the background. At higher powers, the field of view is considerably darkened with the cluster having a total of 15 stars.

Star-Hop#5. IC 2157. Here’s a tougher one to find. While you are looking at NGC 2158, don’t miss a chance to track down IC 2157, another open cluster. IC 2157 is a little less than a half degree west-southwest of NGC 2158, and like that open cluster, much smaller in comparison to M35. In larger telescopes at moderately high power, you may be able to make out IC 2157 as a patch of nebulosity with no individual stars resolved.

Star-Hop#6. NGC 2129. Starting at 1 Geminorum, NGC 2129 is located less than 1 degree due west. At moderate magnifications the cluster is somewhat sparse with only about 40 members.