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Stars 44 Oph and λ Sqr in early evening lunar occultations, Oct. 20-21

Around the onset of nautical twilight in the U.K., the waxing crescent Moon occults naked-eye stars at similar times on consecutive evenings starting October 20. BAA graphic by Ade Ashford.

Magnitude +4.16 star 44 Ophiuchi, otherwise known as b Ophiuchi, lies 13 degrees east of Antares in Scorpius. The former is occulted at the dark limb of the 4½-day-old waxing crescent Moon between 18:06 and 18:18UT (7:06pm and 7:18pm BST) as seen from the British Isles on Tuesday, October 20. The occultation occurs when the Moon is about 6 degrees above the southwest horizon, so the reappearance of 44 Ophiuchi at the Moon's bright limb is unobservable from the U.K.

Fast forward 24 hours and the by now 5½-day-old Moon lies very close to magnitude +2.82 star Lambda (λ) Sagittarii, otherwise known as Kaus Borealis, the tip of the 'Teapot' asterism's 'lid' in Sagittarius. Depending on where you live in the British Isles, the star disappears at the dark lunar limb between 18:10 and 18:23UT (7:10pm and 7:23pm BST) on October 21.

Note that the Moon lies just 8 degrees high in the south-southwest at the disappearance of λ Sgr. If you have exceptionally clear skies, you might see the star's reappearance at the bright limb approximately one hour later, but the setting Moon will be very low in the southwest.

LocationOccultation disappearance
of 44 Oph, October 20 (UTC)
Occultation disappearance
of λ Sgr, October 21 (UTC)
Aberdeen18h 09.9m18h 17.1m
Armagh18h 08.2m18h 13.5m
Belfast18h 08.7m18h 14.3m
Birmingham18h 14.7m18h 19.6m
Cambridge18h 16.9m18h 21.8m
Cardiff18h 14.2m18h 18.5m
Carlisle18h 11.4m18h 17.4m
Cork18h 08.1m18h 11.9m
Douglas18h 10.5m18h 16.1m
Dublin18h 09.4m18h 14.3m
Edinburgh18h 10.1m18h 16.6m
Galway18h 06.4m18h 10.9m
Inverness18h 07.7m18h 14.9m
Kirkwall18h 07.3m18h 15.3m
Leeds18h 13.7m18h 19.3m
Lerwick18h 07.6m18h 16.1m
Liverpool18h 12.8m18h 18.0m
London18h 17.3m18h 21.9m
Newcastle18h 12.5m18h 18.7m
Norwich18h 17.5m18h 22.9m
Oban18h 07.5m18h 14.1m
Pembroke18h 12.3m18h 16.4m
Plymouth18h 14.2m18h 17.7m
Southampton18h 16.7m18h 20.8m
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