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See the 14-day-old Moon occult 30 Piscium on Sept. 30 / Oct. 1

Magnitude +4.3 to +4.4 variable star 30 Piscium, otherwise known as YY Piscium is a naked-eye object occulted at the dark limb of the almost full Moon whilst highest in the southern sky of the UK as September 30 segues into October 1 (UT dates and times). BAA illustration by Ade Ashford.

Naked-eye star 30 Piscium, otherwise known as YY Piscium, is a pulsating long-period irregular variable whose magnitude varies from +4.3 to +4.4. It is a red giant around 425 light-years distant with the following J2000.0 equatorial coordinates: α = 00h 01.9m, δ = -06° 01'.

An occultation of 30 Piscium by the almost full Moon straddling the UT dates of September 30/October 1 is visible from the entire British Isles – a property it shares with the recent lunar occultation of Epsilon (ε) Capricorni. As always, the exact time and duration of the star’s disappearance/reappearance depends on where you live in the UK, which is summarised for a widespread list of locations in a table at the bottom of the page. Note: the table uses Universal Time, as is the convention, so don't forget to add one hour to convert to the corresponding British Summer Time (BST).

Observers in London will see the star disappear at the darkened limb of the 14-day-old Moon shortly after 12:40am BST on October 1 (23:40 UTC on September 30), and reappear at the bright lunar limb almost 74 minutes later. For a skywatcher in Edinburgh, the star's corresponding disappearance and reappearance times are shortly after 12:37am BST (23:37 UTC on September 30) and shortly before 1:54am BST (00:54 UTC), respectively, on October 1.

The disappearance of 30 Piscium will be easy to view in a small telescope as the star can be followed right up to the Moon's dark limb, but the star’s reappearance at the bright lunar limb – near Mare Fecunditatis, between craters Langrenus and Petavius – will be more of a challenge. As with all occultation observations, it pays to be setup and scrutinising the Moon at least five minutes before the predicted times, particularly if you live some distance from your nearest location listed below.

LocationOccultation disappearance
September 30 (UTC)
Occultation reappearance
October 1 (UTC)
Cork23h 27.6m00h 46.3m
Galway23h 28.0m00h 46.4m
Dublin23h 31.9m00h 49.5m
Armagh23h 32.0m00h 49.5m
Pembroke23h 32.8m00h 49.9m
Belfast23h 33.1m00h 50.4m
Plymouth23h 33.4m00h 49.8m
Douglas23h 34.8m00h 51.6m
Oban23h 34.8m00h 51.3m
Cardiff23h 35.4m00h 51.5m
Liverpool23h 36.7m00h 52.9m
Inverness23h 36.9m00h 52.7m
Carlisle23h 37.4m00h 53.5m
Edinburgh23h 37.4m00h 53.5m
Birmingham23h 38.0m00h 53.4m
Southampton23h 38.2m00h 52.7m
Leeds23h 38.8m00h 54.3m
Kirkwall23h 39.1m00h 54.1m
Newcastle23h 39.2m00h 54.7m
Aberdeen23h 39.4m00h 54.8m
London23h 40.4m00h 54.2m
Cambridge23h 41.0m00h 54.9m
Lerwick23h 41.5m00h 55.7m
Norwich23h 42.9m00h 56.2m
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