observer’s log 111 Deep-Sky Wonders for Light-Polluted Skies Bright skies aren’t empty skies. See for yourself how many treasures lie hidden in the glow of a city sky. By James Mullaney here I live, 30 miles west Presented here is a of downtown Philadelphia sampling of 111 deep- (near historic Valley Forge, sky showpieces scattered Pennsylvania), the glow of around the heavens, Wthe nighttime sky is often bright enough most all visible from that I can read my star charts without the midnorthern latitudes aid of a red flashlight. Sadly, for much of through even the the stargazing community, this is a pretty brightest of skies. Since typical situation. Yet despite such blatant stars have the highest intrusions on the once sacred per-unit-area darkness of the night sky, Online brightness, dou- many deep-sky wonders can Want expert tips on ble and multiple still be seen and enjoyed in a observing celestial objects? stars and bright star You’ll find plenty at small telescope. In fact, some SkyandTelescope.com clusters dominate the JII keen-eyed city dwellers have /observing/objects selection. Nebulae and FU IRA even been able to glimpse the galaxies are still well repre- M31 AK brightest quasar, 13th-magnitude 3C 273 sented even though these faint fuzzies suf- in Virgo. Considering that the object is at fer the most from light pollution. You can a distance of around 2 billion light-years, readily find all of them within their re- Use direct vision where color percep- it is amazing that it can be seen at all spective constellations using a good star tion and resolution are important, and under bright conditions, let alone with atlas such as Sky Atlas 2000.0, and the vast averted vision (looking slightly to one apertures as small as 5 or 6 inches! majority are plotted in more basic atlases side of the object) for seeing faint details. and on detailed star maps. In fact, many In the latter case, a dark opaque cloth of these targets appear on this magazine’s covering your head down to your shoul- monthly centerfold star map. ders will help prevent unwanted light A few observing hints are in from streetlights, passing cars, and the order. While low magnifications glowing sky itself from ruining your dark and wide fields of view are typi- adaptation. And finally, as a rule, the cally used for finding deep-sky later at night you observe, the less light objects, higher magnification pollution you will have to contend with has the benefit of darkening as businesses close, neighbors go to bed, the background sky — some- and the busy world around you shuts thing to keep in mind when down for the night. you’re looking through light pollution. Close doubles and Stars, Stars, and More Stars tight clusters (especially glob- Although observers often overlook the ulars) are best seen on nights heavenly hues of bright stars, even under of steady seeing, while nebulae badly light-polluted skies these objects and galaxies should be saved for shine with undiminished splendor. Daz- nights when transparency is excel- zling, blue-white gems like Sirius, Vega, lent. All deep-sky objects are at their and Spica contrast wonderfully with the JII FU best when on or near the meridian and, warm gold, topaz, and orange hues of M17 IRA AK therefore, highest in the sky. stars like Capella, Arcturus, and Aldeba- 110 April 2003 Sky & Telescope Bright sky and telescope? While a brightly lit suburban sky may seem like a veritable deep- sky desert, there are plenty of sights that re- tain much of their splendor even in less-than- ideal conditions. Courtesy Dennis di Cicco. ran and the ruddy supergiants Betelgeuse and Antares. And as the great observer William H. Pickering pointed out long ago, few celestial sights evoke as much real excitement at the telescope as a bright star rising or setting with prismat- ic rays flashing from its stellar heart. There are also many fainter naked-eye stars (most of them variable) of a deep red or crimson hue — stunning sights like Herschel’s Garnet Star (µ Cephei) and La Superba (Y Canum Venatico- rum), or Hind’s Crimson Star (R Lep- oris) when at its brightest. Literally thousands of double stars lie within reach of even the smallest tele- scope — and no two pairs look exactly alike. Many show up as well under light pollution and moonlight as through the darkest of skies. The vivid hues of bright, contrasting color pairs are sights never to be forgotten. Who among us doesn’t re- member our first view of the magnificent topaz and cerulean blue of Albireo? How about the orange and aquamarine of γ Andromedae, or the red and green of α Herculis, or the vivid oranges and blues of 24 Comae Berenices, δ Cephei , ι Can- cri (the Albireo of spring), and 145 Canis sky is the bluish supergiant Rigel. Spectacular Star Clusters Majoris (the Albireo of winter)? And There are also many stunning multiple From double and multiple stars we segue these are only a few of the colored dou- stars featuring three or more resolvable to larger aggregations — open clusters, bles on our list. members. The best-known example is the containing dozens to upward of a thou- White and off-white doubles (especially famed Double-Double (ε Lyrae). Its four sand members. Indeed, some multiple blue-white ones) can also be very striking suns are all white. For a colorful quadru- stars like h 3780 in Lepus are also classi- sights. Just look at the diamonds forming ple system, take a look at ν Scorpii. The fied as star clusters (NGC 2017). Even Castor or the twin “eyes” of nearly equal most spectacular triple groupings are the richer are globular clusters — beehive- pairs like γ Arietis or Porrima (γ Virginis). pale golden components of Herschel’s like swarms of up to a million suns! Some blue-white doubles display a strik- Wonder Star (β Monocerotis) and ο1 Among the best-known and brightest ing brightness difference between com- Cygni — a striking reddish orange, white, open clusters are a number visible to the ponents; one of the best examples in the and blue trio visible even in binoculars! unaided eye that are also beautiful sights in binoculars, even in fairly heavy light pollution. The famed Pleiades (M45), Hyades, and Beehive (M44) Clusters are three examples. The superb Double Cluster (NGC 869 and NGC 884), also barely visible without optical aid, is a truly spectacular sight in low-power tele- scopes. Some of the finest stellar jewel boxes for telescopic viewing are big, bright, and splashy Lassell’s Delight (M35), the Butterfly Cluster (M6), its neighbor M7, and the radiant Wild Duck Cluster (M11). ) (2 N Among the best globulars for Northern β γ TO Cygni Leonis AN R INE Hemisphere observers are the spectacular RA Sky & Telescope April 2003 111 Hercules Cluster (M13) and M22 in Sagit- tarius. All the globulars on our list are in- credible sights when viewed in 6-inch and larger instruments at medium to high magnifications, even under bright skies. Those living farther south shouldn’t miss Omega (ω) Centauri, the finest of all globulars — a naked-eye object and a marvelous sight in any telescope, de- spite its low elevation. Notable Nebulae The most spectacular of all the glowing stellar nurseries visible from northern skies ) (3 I JI is without question the magnificent Orion FU RA M57 KI Nebula, M42. Embedded at the center of A this mottled greenish cloud is the Trapezi- um — an amazing quadruple star in small scopes and a multiple system (actually a that’s virtually always visible: the famed small cluster). The only other diffuse neb- Andromeda Galaxy (M31). I’ve often ob- ulae really suitable for light-polluted skies served it in full moonlight, marveling that are the big and bright Lagoon Nebula I could still see details like the eerie pale (M8, with its attendant cluster NGC 6530) greenish white glow of its nuclear bulge and the Swan Nebula (M17). and the dark bands of its spiral arms. The two best planetary nebulae in Another good target is the big Sculptor northern skies are the famed Ring Nebu- Galaxy (NGC 253), largely ignored due la (M57) and the Dumbbell Nebula to its relatively low declination. Much (M27), the former showing its higher in the sky is cometlike central hole in even the M94 and the stunning pair smallest scopes, while the in Ursa Major, M81 and latter is so conspicuous M82 — one an inclined that it’s visible in binoc- pinwheel, the other ulars. There are many cigar-shaped. The famed smaller, brighter ex- Whirlpool Galaxy (M51) amples of these dying is a beautiful face-on suns that easily punch spiral, but it can be dis- through light pollution appointing in really light- and moonlight. The vivid polluted skies because of NGC 253 greenish blue Saturn Nebula (NGC 7009) and Jupiter’s Ghost (NGC 3242) are pleasing sights. The Cat’s Eye Nebula (NGC 6543), the Blue Snowball (NGC 7662), and the Eskimo Nebula (NGC 2392) M82 are three more showpieces in this class. One object often included with planetaries is the well-known Crab Neb- ula (M1), though it is actu- ally a supernova remnant. The Crab is the brightest such object in the heavens and is visible even in brightly lit skies when medi- um magnification is used. Galaxies Galore M81 Many observers seldom think of looking at galaxies under heavy light pollution or bright moonlight. But there’s at least one member of this class 112 April 2003 Sky & Telescope observer’s log observer’s 111 Treasures for Light-Polluted Skies Sky Atlas 2000.0 Object Constellation Type R.A.