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Winter: using our chart here, start your deep-sky hunting!

WINTER IS THE BEST SEASON for urban and suburban astronomers in several ways. The nights are long and the air is clean and crisp. That's particularly important in densely populated areas, because clean air allows artificial light to escape to outer space. Dirty or humid air reflects lots of light pollution down to the ground -- and into your telescope and eyes.

Above all, winter is when many of the brightest deep-sky objects are on display --objects that can punch through light-polluted skies. And you don't need fancy equipment to appreciate them; they look good even in small scopes and binoculars.

Most spectacular of all is the constellation Orion. Its magnificent nebula Messier 42 is easy to locate below Orion's belt using the all-sky charts starting on page 17. M42 is visible as a small glow around a few bright stars in binoculars, and it's glorious through any telescope.

But let's focus now on Auriga, a constellation that's less well known but still spectacular. Its five-star pentagon (including one star borrowed from Taurus) is easy to recognize. It floats high on winter nights as shown on our all-sky charts, above trees, buildings, and the bright sky-glow that hugs the horizon. And four of winter's finest star clusters are in or near this constellation.

We'll start with the cluster that's least impressive but easiest to locate. Messier 38 lies almost exactly halfway between Auriga's stars marked Theta (9) and Iota (t) on the close-up chart on the facing page. (See page 57 if you need help using it.) M38 pops out immediately in good suburban skies, but it can be a little hard to spot in bright cities because its stars are fairly faint and spread over a relatively large area. If you're having trouble, try star-hopping from the cute arc of star pairs northwest of the star 14 Aurigae, a formation that SkyWatch editor Alan MacRobert has dubbed the Leaping Minnow.

M38 consists of two wavy lines of stars on a background glow of fainter, unresolved specks. The lines cross each other; in the eyepiece M38 always reminds me of a saguaro cactus.

Look also for the lovely, much subtler cluster NGC 1907 in the same field of view, 1/2[degrees] to the south of M38.

M36 lies 32/3[degrees] southeast from M38: toward the line connecting Theta Aurigae with Elnath. M36 stands out much better than M38 in light-polluted skies; it has fewer stars, but they're brighter and packed into a tighter group. Some people find part of it reminiscent of a dipper, like a miniature version of the Pleiades. What do you think?

Continuing 32/3[degrees] in the same direction, but bending slightly north, you land on the remarkable cluster M37. This tends to look like a subtle blur through binoculars and small telescopes, about the same size as M38 but considerably brighter. Bigger scopes and higher magnifications reveal it as one of the most spectacular open clusters in the sky--a glorious ball containing dozens or even hundreds of stars. The cluster's brightest star is a splendid red giant right in the center.

My favorite open cluster of all is M35, which lies 9[degrees] south-southeast of M37 in the constellation Gemini. Observers usually locate it off the stars marked Mu ([mu]), Eta ([eta]), and 1 Geminorum, which represent the westernmost foot of the Gemini Twins' stick figure. M35 is quite large, so it's usually easiest to spot at low magnifications. It's more tightly packed than M38 but not as dense as M37 or M36.

Messier 35 is the cluster that has it all. It includes nearly as many stars as M37, but whereas M37's stars are all fairly faint, M35's cover a huge range of brightness.

Two or three are easy to see even in binoculars, but larger instruments reveal ever more, and show that the brightest stars are distinctly reddish.

And there's a bonus: the small, dim cluster NGC 2158 fits in the same field of view. Look for it off M35's southwestern fringe. NGC 2158 is almost five times more distant than M35, so it can be tough to spot in bright skies or with small scopes. But big backyard telescopes show that it's actually richer than M35.

Honorable mention goes to M1, the famous Crab Nebula. Start by looking 0.9[degrees] north-northwest of bright Zeta ([zeta]) Tauri for the handsome 7th-magnitude double star Struve 742 ([summation]742), which is easily split at 100x. Then look for a faint, moderately large patch of glow 1/2[degrees] west from there.

M1 is notoriously tricky to spot in bright skies, especially through small telescopes. Many beginners tackle it early because it heads the list of deep-sky objects compiled by 18th-century comet hunter Charles Messier. Unfortunately, it's also probably the toughest object in the list of 45 that Messier initially published.

So you may need averted vision to spot it, and it will probably just look like a faint oval smudge. But M1 is worth the effort because it has great historical and scientific importance. It's the remnant of a naked-eye supernova whose brilliant light reached Earth in AD 1054. It's probably the youngest deep-sky object you'll ever see -so young that it has changed significantly since Messier first spotted it.

The other clusters and double stars marked on the map are described in the table above.

Additional Clusters and Double Stars in and near Auriga

Object       RA                       Dec.

NGC 1664     [4.sup.h] [51.1.sup.m]   +43[degrees] 40'

NGC 1746     [5.sup.h] [03.8.sup.m]   +23[degrees] 46'

14 Aurigae   [5.sup.h] [15.4.sup.m]   +32[degrees] 41'

[SIGMA]698   [5.sup.h] [25.2.sup.m]   +34[degrees] 51'

118 Tauri    [5.sup.h] [29.3.sup.m]   +25[degrees] 09'

26 Aurigae   [5.sup.h] [38.6.sup.m]   +30[degrees] 30'

Object       Description

NGC 1664     In Auriga. Faint but well-defined cluster;
             like a palm tree.

NGC 1746     In Taurus. Very large, loose cluster,
             good in binoculars.

14 Aurigae   Lovely colorful double star at 60x; 100x
             shows third star.

[SIGMA]698   In Auriga. Wide yellow-and-blue double at 60x.

118 Tauri    Double star, easy split at 100x.

26 Aurigae   Medium-wide yellow-and-blue double at 60x.
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Title Annotation:Observing: Deep-Sky Seasons
Author:Flanders, Tony
Date:Jan 1, 2013
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