February 17, 2019

AstroEvent: A Close Binary Occultation.

Astronomical occultations are always fun to catch. Unlike other astronomical events that often happen over glacial time scales, occultations happen with abrupt swiftness. And besides just being plain cool, occultations can produce real scientific value, data that you can contribute to from your own backyard… and there’s no bigger occulting body in the night sky than our own Moon. This week, I’d like to bring to your attention a fairly bright and interesting star that is currently undergoing a series of lunar occultations this year; Sigma Scorpii. This star shines at magnitude +2.9 in the heart of the constellation Scorpius and is itself a close binary difficult to separate with a telescope. This star is also known as Al Niyat, or Arabic for the “Shield of the Heart,” possibly referring to its visual proximity to brilliant Antares. Sigma Sco is itself a complex system, with a 9th magnitude companion about 20” distant.

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