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March 23: See the Altai Scarp
Today’s target is for the early risers: Open cluster M18 in Sagittarius.
Rising around 2 A.M. local daylight time, by 4:30 A.M. the cluster has reached 20° in altitude above the southern horizon. It sits above the famous Teapot asterism, some 8.5° north-northeast of Lambda (λ) Sagittarii, the top of the Teapot’s lid, and near Sagittarius’ border with Scutum and Serpens Cauda.
A nearer jumping-off point is magnitude 3.8 Mu (μ) Sag; from this star, scan just over 4° north-northeast to land on magnitude 6.9 M18. Spanning just under 10’, M18 is a scattered grouping of young stars containing somewhere between one dozen and two dozen stars. 100x or so is the best magnification, according to Contributing Editor Michael E. Bakich, who notes that higher magnifications spread out the cluster’s stars too much for easy identification, mixing them in with the many background stars in this rich region of the Milky Way.
Sunrise: 6:57 A.M.
Sunset: 7:17 P.M.
Moonrise: 10:14 A.M.
Moonset: 1:21 A.M.
Moon Phase: Waxing crescent (42%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. local time from the same location.
