My first Magazine Sky & Telescope - 01.2019

JANUARY 2019 OBSERVING Going Deep by Howard Banich NE Fleming’s Semicircular Indentation Can you see the Horsehead Nebula? It’s all about contrast and scale. ! Horsehead — . . . I carefully pinpointed its exact location with Uranometria and at 53× centered the ﬁ eld in the eyepiece. Then with the 16-mm at 182× and the O III ﬁ lter I looked — nothing. Rats. Let’s try the UHC — I looked — wait a minute, wait a minute — a little more averted vision, then after all these 23 years I saw it with my own eyes . . . It was quite a bit larger (and fainter) than I expected (which is what most people say, I hear). It was more like a darker notch taken out of the sky rather than a silhouette against a bright nebula. Although that may sound rather contradictory, that was my impression. After looking at it in Chuck Dethloff’s 24-inch and an h-beta ﬁ lter (which showed it very clearly) he loaned me the ﬁ lter (which was a 2-inch) and I tried it on my 55-mm Plossl at 53× — wow! Very obvious now with the ﬁ lter and the wider ﬁ eld of view. This was the most satisfying view of anything I’ve ever looked at. This was magical. 58 JA N UA RY 2 019 • SK Y & TELESCOPE p ICONIC NEBULA The Horsehead Nebula is silhouetted against the brightest part of the emission nebula IC 434, which stretches horizontally (south) through the center of the photo from the bright star Alnitak (Zeta Orionis, left center), the easternmost star of Orion’s Belt. The naked-eye star Sigma Orionis is just out of view at top. The Flame Nebula, NGC 2024, is east of (below) Alnitak, and the much smaller NGC 2023 is due south (right) of the Flame and northeast (below and left) of the Horsehead. These are my notes from the early morning of October 13, 1991, which was also the ﬁ rst night I had my then-new 20-inch f/5 Obsession Dobsonian under a dark and trans- parent sky. I was with a small group of observers at Indian Trail Spring in central Oregon, which the following year became the site of the Oregon Star Party. The entire night was astounding, but seeing the Horsehead for the ﬁ rst time positively blew me away. Little did I know I didn’t need a 20-inch telescope to see the Horsehead Nebula, and that I could have seen it with my 8-inch scope decades earlier if I’d been under a good enough sky. But as a kid I didn’t even know the Horsehead was pos- sible to see visually. Today it’s one of the most famous deep-sky objects and after M42 probably the second most sought-after object in Orion. However, the Horsehead is nearly impossible to see I got pretty excited the ﬁ rst time I saw the Horsehead Nebula:

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