BAA electronic bulletin
PERSEID METEOR RATES INCREASING
Although the weather has been somewhat variable over the past few days,
observers across the British Isles have reported increasing Perseid meteor
activity. The Perseids are one of the most reliable showers of the year,
producing an abundance of fast, bright meteors, many with persistent trains.
Unfortunately, moonlight will interfere with observations of the shower peak
this year, with Full Moon occurring on August 07, but the maximum occurs
over a weekend which is very convenient.
Alex Pratt (Leeds) recorded his first Perseid meteor on July 24/25 and
he had detected 62 shower members by the end of the month. The shower will
continue to be active until about August 21. The shower's activity displays
a marked 'kick' around August 8-9 and steadily increasing observed rates may
be expected from then until the peak, which is expected at around 19h UT
(20h BST) on Saturday, August 12 this year. This means that the two nights
of Friday night to Saturday morning (August 11-12) and Saturday night to
Sunday morning (August 12-13) will probably be equally productive for
observers in the UK.
Observers watching after midnight on August 11-12 should experience
increasing activity towards dawn, as the shower radiant at RA 03h 13m, Dec.
+58° (near the Double Cluster, on the Perseus-Cassiopeia border) climbs
higher in the eastern sky. Activity should be just starting to decline by
the time darkness falls on Aug 12-13. The Moon will be a waning gibbous in
Pisces/Cetus over the peak nights so it is suggested that visual observers
minimize the effects of moonlight by positioning themselves so the Moon is
behind them and hidden behind a wall or other suitable obstruction.
It is hoped that, weather permitting, observers will cover shower
activity on the nights to either side of the maximum, for example on the
Thursday night to Friday morning (August 10-11) and Sunday night to Monday
morning (August 13-14). The Perseids are also an ideal target for digital
imaging due to the relative abundance of bright meteors, although exposures
will need to be kept quite short with a bright Moon in the sky.
The best observed rates are found when the Perseid radiant is highest
in the sky during the pre-dawn hours, but even in early evening the radiant
is already at quite a favourable elevation above the horizon. Under
cloudless skies, but with the Moon above the horizon, observers can expect
to see between 25 and 30 meteors each hour near the peak. Even in towns or
cities observed rates may still be around 5 to 10 an hour in the early
morning hours when the radiant is high.
Observations in recent years have revealed noticeable variations in
activity from year to year and there was a brief but well recorded outburst
in Perseid rates in 2016 (see J. Brit. Astron. Assoc. 126(5), 264-265). We
shall just have to wait and see what is in store for us in 2017.
The BAA's visual meteor report forms, available as downloads in both
pdf and Excel formats, enable observers to record the details of each meteor
seen. These include: time of appearance (UT); apparent magnitude
(brightness); type (shower member, or random, 'background' sporadic);
constellation in which seen; presence and duration of any persistent train.
Other notes may mention flaring or fragmentation in flight, or marked
colour. Watches should ideally be of an hour's duration or longer (in
multiples of 30 minutes). Observers are reminded to carefully record the
observing conditions and the stellar limiting magnitude.
By whatever means you observe the Perseids this year, please submit
your results to the BAA Meteor Section via firstname.lastname@example.org.
Please note that the Section Director will be away in the USA from August
9th to 24th.
This e-bulletin issued by:
Dr John Mason
Director, BAA Meteor Section
5th August 2017
BAA-ebulletin mailing list visit:
(c) 2017 British Astronomical Association http://www.britastro.org/
Good Clear Skies
Colin James Watling
Various Voluntary work-Litter Picking for Parish Council (Daytime) and
also a friend of Kessingland Beach (Watchman)
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)
Lyra Main Website: http://www.lyra-astro.co.uk/