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Friday, 9 August 2013


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2013 August

Late July will have been a frustrating time for UK based meteor observers. Despite Full Moon having occurred as long ago as July 22nd, the Moon will have only moved out of the evening sky very slowly and even by the time of Last Quarter on July 29th, there will have only been around an hour of dark sky before moon rise.

Fortunately, things get rapidly better in early August as the rapidly thinning crescent Moon will be quickly making its exit from the morning sky. New Moon occurs on Aug 6th and the crescent Moon only makes very slow progress into the evening sky. By Perseid maximum on the 12th, though only 2 days away from First Quarter, it is located near the Virgo/Libra border and is setting at around the time of evening twilight.

The consequence of the above is that not only do we get an effectively moon-free Perseid maximum, we also get a good view of the Perseid rates rising during early August.

Perseid maximum is actually predicted for Aug 12d18h UT. The peak is not particularly sharp and so rates will have dropped little before it gets dark in the UK. The best observed rates are likely to be seen late in the night of Aug 12-13. However good rates are also likely during the nights of Aug 10-11, 11-12 and 13-14, so don't just focus on the night of Aug 12-13 (and risk it being clouded out).

The Perseid radiant is circumpolar from the UK, so you should start to see some Perseids as soon as it gets dark. The best observed rates are likely to occur in the later part of each night when the radiant is higher in the sky.

Few Perseids will be seen if you look directly at the shower radiant (their paths will be too short to easily see against the star background). For the best observed rates, look at any area of sky around 20-30 degrees from the radiant and at an altitude of around 50 degrees (but obviously tailor this to take into account local factors such as sky obstructions and light pollution)

The Perseid shower is rich in bright meteors - a good target for imaging. The shower is also good for trained meteors, with around a third leaving persistent trains.

Care should be taken to identify the correct location for the Perseid radiant (see the chart below) before observing, as this changes significantly between late July and the peak.

Active alongside the Perseids in early August are the later parts of the southern Delta Aquarids (SDA) and Alpha Capricornid (CAP) showers, which peaked around the end of July, along with the more general activity of the sporadic background. Some older listings include showers such as the northern Delta Aquarids and the southern Iota Aquarids, although nowadays these tend to be grouped into the "Antihelion source" (ANT). Numerous other minor showers have also been listed over the years including the Alpha Cygnids, Gamma Draconids and Lacertids, although the existence of these is open to question.

Later in the month, some activity is produced by the Kappa Cygnids, which peak Aug 18-20, and the Alpha Aurigids which peak at the end of the month. However, observation of both showers will be significantly affected by moonlight in 2013

Original text

Good Clear Skies
Colin James Watling
Various Voluntary work-Litter Picking for Parish Council (Daytime) and also a friend of Kessingland Beach (Watchman)
Lyra Website:
Real Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
Information -- And More Info

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