My first Magazine Sky & Telescope - 01.2019

Observing in the Park Pleaides (M45) or 600 million for the late-middle-aged Beehive (M44). t COMPLEX NEBULA Situated in Camelo- pardalis, the Giraffe, the planetary nebula NGC 1501 lies around 4,000 light-years away. The bright central star that can be seen in this image earned this object its nickname, the Oyster Nebula. Remember, you will not see this intricate nebula in all its i nest detail (and the colors here are arbi- trary), but as you peek through your scope on a cold winter’s night, bear this image in mind as you remind yourself that you are in fact seeing the last gasps of a star across the vast distances of space. A Dip into Perseus If you proceed from Delta Cas to Epsilon and then double back to form an imaginary ﬁfth leg to Cas- siopeia’s W, you land atop the huge, loose open cluster Stock 2, which straddles the Cassiopeia-Perseus border. Measuring roughly 1° across and dominated by two dozen 8th- and 9th-magnitude stars, it’s best observed at the lowest magniﬁcation that your telescope can achieve. The cluster’s apparent size indicates that it must be nearby, and indeed it lies just 1,000 light-years away. At an estimated age of 170 million years, Stock 2 is also by far the oldest cluster in our tour. You might guess that by the fact that so many of its stars are almost identical in bright- ness. In older clusters, all the brightest, most massive stars have already burned out. Many people see Stock 2’s stars as the ﬁgure of a giant. One hand grasps a chain of 6th- and 7th-magnitude stars that stretches 2° south to the peerless Double Cluster. The apparent proximity of Stock 2 to the Double Cluster is an illusion. Stock 2 lies in our galaxy’s Orion-Cygnus Arm (also called the Local Arm and many other names), the same arm that hosts our own solar system. All the other clusters we’ve discussed so far are much farther away, in a particularly active star-forming region of the neighboring Perseus Arm. The superposition of nearby Orion-Arm clusters with luminous young Perseus-Arm clusters is what makes this region so rewarding to explore. I never tire of viewing the Double Cluster through any instrument at any magniﬁcation under any conditions. Its components are among the most luminous open clusters known; each appears as bright as the Beehive Cluster despite being 14 times more distant. If the Double Cluster were at the same distance as the Beehive, it would appear as bright as Jupiter and bigger than Cassiopeia’s W. For more informa- tion on this amazing cluster pair, see Sue French’s discus- sion on page 54. Object Type Mag(v) Size/Sep RA Dec. WZ Cassiopeiae Carbon star 6.9–8.5 — 0 h 01.3 m +60° 21′ Eta Cassiopeiae Double star 3.4, 7.5 13″ 0 h 49.1 m +57° 49′ NGC 457 Open cluster 6.4 13′ 1 h 19.5 m +58° 17′ M103 Open cluster 7.4 6′ 1 h 33.4 m +60° 39′ NGC 663 Open cluster 7.1 15′ 1 h 46.3 m +61° 13′ NGC 659 Open cluster 7.9 6′ 1 h 44.4 m +60° 40′ NGC 654 Open cluster 6.5 6′ 1 h 44.0 m +61° 53′ Stock 2 Open cluster 4.4 60′ 2 h 15.6 m +59° 32′ Double Cluster Cluster pair 2.9 45′ × 30′ 2 h 20.7 m +57° 08′ Stock 23 Open cluster 5.6 14′ 3 h 16.3 m +60° 02′ U Camelopardalis Carbon star 7.0–8.0 — 3 h 41.8 m +62° 39′ Kemble’s Cascade Asterism — 150′ 3 h 57.4 m +63° 04′ NGC 1502 Open cluster 5.7 7′ 4 h 07.8 m +62° 20′ UV Camelopardalis Carbon star 7.5–8.5 — 4 h 05.9 m +61° 48′ Planetary nebula 11.5 52″ 4 h 07.0 m +60° 55′ NGC 1501 Angular sizes and separations are from recent catalogs. Visually, an object’s size is often smaller than the cataloged value and varies according to the aperture and magnii cation of the viewing instrument. Right ascension and declination are for equinox 2000.0. 66 JA N UA RY 2 019 • SK Y & TELESCOPE Jewels of the Wintry North

My first Magazine Sky & Telescope - 01.2019 | Page 68