Cold weather keeping you inside at night? Make the most of your telescope time with these easy-to-find deep-sky gems.
Early spring nights, while more clement than those of winter, can still be cold and damp. I know some amateurs who don't set up a telescope when it's below freezing. Were I to abide by that standard I'd kiss almost six months of observing goodbye!
That's why I created a list of cold-weather deep-sky objects that you can find quickly with an absolute minimum of star-hopping. All of them lie within 1° of a bright, naked-eye star. Point your telescope at the star and you're practically there. My maxim for cold-night observing is simple: Keep suffering to a minimum.
Some of the 16 featured objects are familiar faces like the Crab Nebula, but I've tried to include the offbeat as well. The objects are divvied up into three categories based upon general location in the sky. I'll list the naked-eye star first that will guide you to the object(s) I want to highlight.
Epsilon (ε) Cassiopeiae
IC 1747 and Czernik 6 : Also known as the Holepunch Nebula, IC 1747 is a 12th-magnitude planetary nebula 13 arcseconds in diameter located ½° southeast of Epsilon Cas and 1′ southeast of a 12.7-magnitude star. A small, circular puff of light caught my eye at 64×, but increasing the magnification to 245× and adding an Ultra High Contrast (UHC) filter transformed it into a thick ring with a slightly darker center. I love digging out the white dwarf stars at the centers of planetaries, but this 15.4-magnitude ember eluded my gaze.
High magnifications work wonders on smaller planetary nebulae, often revealing shapes, central stars, and brighter nodules embedded within their disks. If at first you see little more than a smudge, try 200× or even 400× to sweeten the detail. Don't be bashful.
A little more than ½° southeast of IC 1747 you're in for a treat: Czernik 6. At first I thought I saw only a 9th-magnitude star but then I noticed nearly a dozen fainter members huddled in its light. Only 2′ across, this dainty gem is worth the side tour!
Front and Center
Zeta (ζ) Tau
Crab Nebula (M1) : So many nebulae look like streaky, smoky things but the Crab is different. Is it my imagination or does it have a certain sheen to it that other nebulae lack? If so, might it be due to the fact that much of the Crab's light arises from synchrotron radiation rather than the usual reflection or emission stoked by starlight? High-speed electrons spiraling around the intense magnetic field associated with the Crab Pulsar — the neutron star remnant from the supernova explosion of 1054 AD — emit synchrotron radiation in visible light and other wavelengths, giving shape to this amazing nebula. The filaments or "crabby parts" so well seen in photographs are the gaseous remains of the original star that continue to expand outward at 1,500 km/s.
I see a super-smooth oval cloud at my lowest magnification, but to really enjoy this arthropodal delight, I switched to a wide-field 245× eyepiece. Whoa! The bright central region that extends southeast-northwest appeared mottled with subtle variations in brightness and density. With averted vision I spied a lobsterlike, flared "tail" at the Crab's west end and two fat, crablike claws enclosing a darker, nebula-free region along the east side. Averting my vision continuously I teased out bits of filamentary structure throughout the nebula, but especially along the south side. Numerous faint field stars sparkle "through" the nebula, adding an unanticipated beauty to the Crab's eerie glow.
Lambda (λ) Ori
Collinder 69: Orion's itty-bitty head is that little obtuse triangle of stars centered over Betelgeuse and Bellatrix. Much of it is also a true star cluster centered on 3rd-magnitude Lambda Orionis — a delightful object for both binoculars and small telescopes. Use your lowest power. The cluster's most striking feature is a straight up-and-down row of three 7th-magnitude stars directly below Lambda that resembles Orion's Belt tipped on its end.
Collinder 69 contains about 20 stars in a space of 70′ and hails from 1,630 light-years, nearly the same distance as the Orion Nebula. It's also "just a kid," born just 5 million years ago, or roughly when the first hominins evolved. In a sense, our species has grown up with Collinder 69. To hold it in our gaze reminds us of our own origins.
Mu (μ) Orionis
Abell 12: This small 12.4-magnitude planetary nebula does its best to hide in the glare of 4th-magnitude Mu Orionis, but that only makes me want to see it more. Located 1′ southeast of Mu this perfectly round nebula is faintly visible without a nebula filter — but don't bother. Start with a UHC or O III filter and an 8-inch or larger scope for a much better view.
I spotted the 37″ disk with 142× and a UHC filter. Upping to 400× the little fella comes into its own, revealing a darker center with averted vision that betrays its true morphology: a ring!
NGC 2141: Another splendid sight for 8-inch or larger scopes, and you get to use Mu again to get there! Look ¾° north of the star for a 10′-wide stellar pincushion of faint stars. At low power I can make out about 75 stars, but 142× reveals more than 150. Although NGC 2141 has a total magnitude of 9.4, most of its members are dimmer than 13th magnitude, giving the cluster a semi-granular appearance. In fact, the swarm contains some 365 suns in total; the reason for its faint appearance likely has to do with its distance — a monster 13,850 light-years. I'd love to see this one in a really big scope!
Alpha (α) Geminorum
Galactic "Paw Prints": We don't usually associate galaxies with the winter sky, but they're there if you poke around the edges. I tracked down four faint 14th-magnitude fuzzies just 30′ south of Castor in Gemini that resembled paw prints — IC 2196 (magnitude 13.7); IC 2192 (13.8); IC 2199 (14.1); and IC 2194 (15.1). Using 245× each appeared as a round smear of light between 20″ to 25″ across (except for IC 2192 that's just 15″ across) with a tiny bright core.
On the Rise
Gamma (γ) Leonis
NGC 3226-27: What a beautiful sight! And so easy to find just 50′ east of Algieba in Leo's Sickle. The two galaxies comprise an interacting pair located approximately 77 million light-years from Earth. The smaller of the two, NGC 3226, a 12th-magnitude dwarf elliptical, shares a common envelope with the larger NGC 3227, an 11.1-magnitude spiral. I see two galaxies touching at 142×, each with a distinct character. NGC 3227 is elongated northwest-southeast with a prominent, nearly stellar nucleus. NGC 3226 appears a little fainter, round with a brighter but more diffuse core.
Alpha (α) Lyncis
Arp 315 galaxy group and NGC 2859: Found just 40′ southwest of 3rd-magnitude Alpha Lyncis this clutch of fuzzies is perfect for middle- and high-magnification viewing with 8-inch and larger telescopes. I detected 10 galaxies spread over 20′, but we'll focus on the group's core: NGC 2832, NGC 2831, and NGC 2830. NGC 2832 is the brightest at magnitude 12.3 and easy to pick out at low magnification. I saw a bright, nonstellar core glowing lanternlike inside a fainter 2.3′ × 1.9′ disk tilted northwest-southeast. Be sure you don't miss NGC 2831 — a tiny, nearly stellar galaxy (magnitude 14.7) that overlaps NGC 2832's disk southwest of its nucleus. At first I thought it was a star but 245× divulged a small, hazy envelope.
Just 1.3′ southwest of NGC 2832, NGC 2830 (magnitude 14.4) flickered in and out of view as a highly elongated misty streak 1.3′ across and just 0.3′ thick — a lenticular galaxy viewed edge-on. The trio lies 300 million light-years away.
Our final outpost is the barred lenticular galaxy NGC 2859 located 42′ east of Alpha. This one's a little closer to home at 83 million light-years and shines at magnitude 11.4 with a brighter, extended core region punctuated by a bright, starlike nucleus.