February 2010

Winter Cluster Challenge

M38 and NGC 1907M35 and M38 are two beautiful open clusters that are well positioned for observing during the winter months. M35 is located in western Gemini, just a few degrees north and west of η Geminorum. It is a big cluster spread across an area nearly the size of the full moon. At magnitude 5.3 overall, and with nearly a hundred stars of 7th through 11th magnitude, M35 is an easy target even in heavily light polluted skies. Smaller and fainter at magnitude 7.5 overall, M38 is also a beautiful object. It consists of about a hundred stars, with the brightest ones forming a very distinctive letter “π” that is clearly visible even with small telescopes (you can see the “π” upside down in the photo to the right).


M35 and NGC 2158While these clusters are quite beautiful and easily observed from washed-out skies, there is something that sets them apart from the other many bright open clusters visible in the winter skies: both of these have fainter clusters within the same field of view. The combination of two clusters in one field of view makes them a particularly interesting sight. Because these fainter clusters are at the edge of visibility for urban observers, they make great challenge objects when observing in washed-out skies. I have more information for those of you wanting to take up this challenge....


Photos of M38  (upper, with NGC 1907 at the bottom edge) and M35 (lower, with NGC 2158 at the bottom-right edge) courtesy of Land of Oz Observatory.


Pocket Sky Atlas

A good star atlas is essential for finding your way around the night sky and locating interesting objects. This is especially true in washed-out skies, where you may not see enough stars to easily recognize all the constellations. But which star atlas is right for you? In this first of a series of atlas reviews, I’ll look at Sky & Telescope’s Pocket Sky Atlas. This is a beautifully printed atlas designed specifically for use in the field. Its spiral binding and compact format make it easy to use at the telescope. It’s also a good match for washed-out astronomers to use for star-hopping because its magnitude limit for stars corresponds well to what you can see using finder scopes and binoculars in light-polluted skies, and the deep sky objects included cover just about anything you can hope to see with a telescope from urban areas. On the other hand, if you are looking for something to help you learn the constellations and generally find your way around the night sky, the Pocket Sky Atlas may be the wrong tool: the charts are too narrow and too detailed for that. To make effective use of this atlas you should already be able to locate the major constellations. Allow me to explain further...