Late tonight, moonless skies provide nice deep-sky observer. Strive for open cluster NGC 6939, neighbor to the well-known Fireworks Galaxy.
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August 17: Mars at Gemini’s feet
Wait till after about 10 P.M. tonight to start your deep-sky observing and the Moon received’t be a trouble. A superb goal is NGC 6939, an open cluster in Cepheus the King. This cluster is kind of compact, about 8’ throughout, and shines at eighth magnitude. You may find it within the north late tonight — by 10 P.M. native daylight time, it’s some 60° excessive, to the higher left of Alderamin, Cepheus’ alpha star. From this magnitude 2.5 solar, slide just below 6° southwest to land on the cluster.
Though NGC 6939 is an open cluster and these teams are younger, it’s one in every of our galaxy’s older such clusters, at some 1 billion to 2 billion years previous. It may be considered in binoculars, however bigger apertures will pull out its stars as factors, fairly than merely exhibiting a dim, amorphous glow.
NGC 6939 additionally has a well-known neighbor — some ⅔° to its southeast (and a couple of.1° southwest of magnitude 3.4 Eta [η] Cephei) is NGC 6946, a face-on spiral often known as the Fireworks Galaxy. Glowing at magnitude 8.9, this galaxy has had at the least 10 supernovae pop off inside it over the past century! Examine that with our personal galaxy, which sees about one each century.
Spanning roughly 10’, NGC 6946 generally is a bit difficult as a result of its mild is unfold out over a comparatively massive space, making it seem dim. It’s additionally positioned behind a swath of light-absorbing mud inside our personal galaxy. Even so, it may be present in binoculars and it’ll present up as a faint, comparatively detail-less glow in smaller scopes. In bigger telescopes (11 inches), the brighter core and fainter arms turn out to be distinct, and develop much more detailed as you scale up your aperture.
Each objects present up effectively in astrophotos, making this a preferred pair for imagers to focus on.
Dawn: 6:14 A.M.
Sundown: 7:53 P.M.
Moonrise: 12:47 P.M.
Moonset: 10:38 P.M.
Moon Section: Waxing crescent (41%)
*Instances for dawn, sundown, moonrise, and moonset are given in native time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. native time from the identical location.
Should you’re keen to remain up late, you’re in luck: NGC 7293, the Helix Nebula, is highest round 1 A.M. native daylight time on August 19, when it stands some 30° above the southern horizon. It is usually cataloged as Caldwell 63.
Positioned in Aquarius, the Helix is a stunning round planetary nebula generated in addition to lit up by the dying star at its heart. Though it’s eighth magnitude — fairly shiny for a planetary — its inside portion covers some 16’ of sky, making it one of many bigger planetary nebulae we all know. It additionally signifies that (just like the Fireworks Galaxy yesterday) its mild is unfold out over a bigger space, making its general floor brightness low. However that doesn’t imply it will possibly’t be seen — actually, it will possibly nonetheless be caught in binoculars or a small scope. On a really darkish night time (and when you’ve got superb eyesight), you might even be capable of see it with none optical help! It’s in a patch of sky in southwestern Aquarius devoid of shiny stars, however you possibly can hop some 7.8° southwest of Third-magnitude Skat (Delta [δ] Aquarii) to seek out it. For a fainter however nearer signpost, use Fifth-magnitude Upsilon (υ) Aqr — it’s simply 1.2° west of this star.
Should you’ve received a big scope, screw in a nebula filter to convey out extra element, together with brightness variations alongside the sides of its ring.
Alison Klesman is senior editor of Astronomy journal. She holds a Ph.D. in astronomy and has studied a wide range of subjects, from minor planets to supermassive black holes.
