Sunday, January 6, 2013

Cassiopeia's starry treasures

Winter has been as usual cloudy and rainy so far in my area, but windows open in the weather that I make use of wherever possible. Last weekend before New Year's was no exception, and despite the very bright waning gibbous moon I rolled out the 15-inch into the driveway and went on the hunt. Because of the light pollution and interference from the moon, galaxies and faint nebulae were out of the question, but another class of deep sky objects not affected nearly as much was not. Open clusters when they are reasonably bright can penetrate the milky and light polluted skies enough to be observable from an urban area. So I looked up two of Cassiopeia the Queen's open clusters, Trumpler 1 and Markarian 6. I have repeatedly observed the Messier and NGC open clusters that showed themselves to my telescopes, but these objects I was unaware of until I read the January 2012 issue of Sky & Telescope magazine. 
Both are remarkably obvious even in a small telescope, just what's needed for urban and suburban stargazers. Trumpler 1 is a small but bright open cluster that mainly consists of two lines of stars. Put together, their arrangement led to this star cluster being dubbed "The Zipper" due to the brightest stars resembling the teeth on many a zipper found in everyday clothing. Although the poor seeing hid fainter stars lurking among the brighter members, at 227X I counted some 15 to 20 stars in this eight magnitude object. With an apparent size of some five arc-minutes, medium or high powers are best for this eye catching open cluster.
Markarin 6 is about the same in apparent size as Trumpler 1, but a magnitude brighter. At 227X I could only count some ten stars, doubtlessly there are more but very faint stars can be invisible when the seeing is poor, and it was bad that night. That can smear dim stars into invisibility. The overall pattern to me resembled a hockey stick or fishhook, which makes telling it apart from the background star clouds easy from a city. Although the sky conditions would lead many with larger telescopes to stay inside and watch TV or read a book, I also spent time observing Jupiter and the moon, which always shows something of interest. Other objects I observed were the planet Uranus, which looked like a tiny turquoise disk, the triple star 40 Eridani, the Orion nebula and the planetary nebulae IC-2149 in Auriga the Charioteer. Before taking the telescope down for the night,  I looked at NGC-1535 in Eridanus the River. That object is a double shell planetary nebula which has been nicknamed "Cleopatra's Eye." I can see the ring shaped inner shell in the middle of the larger and fainter round outer shell, with the central star faintly visible. I also paid a visit to the winter globular cluster M-79 and the planetary nebula IC-418 in Lepus, the Hare. Poor as the weather usually is on the Gulf Coast, I often manage to see objects dimmer and more challenging than I thought possible. Persistence pays off, and so does looking for the brighter ones when you can't drive to a darker area. From your home, chances are, there's a lot more to see than you might imagine.