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From: TerryMoselaol.com
Date: Tue, 7 Dec 2004 19:40:22 EST
Subject: 2004's best meteors, TV, Lecture, IAA Party

Hi all,

1. GEMINIDS: The best meteor shower of the year, and perhaps the best we'll 
see for a few years, is approaching! (Next year, and in 2006, they will be 
affected by moonlight.)

The Geminids are now by far the best of the annual showers, with peak rates 
of about 120 per hour in excellent conditions, much better than the Perseids or 
normal Leonids. This year the Moon will be out of the way, giving dark skies 
if you can get away from light pollution. They start about Dec 8 and activity 
continues to build towards maximum, then fall off until about about Dec 15/16, 
but the peak of activity should be on the night of Dec 13/14. Different 
authorities give different times for the actual peak: Neil Bone (BAA) says about 
16.00 UT, others say about 24.00. 

But in the case of the Geminids it's not that critical, as the peak is fairly 
'broad', not sharp like the Quadrantids or some of the extra 'Leonid bursts'. 
In other words, levels can be quite high for 8-10 hours before, and 4-6 hours 
after, maximum. And the radiant is above our horizon for all of the hours of 
darkness in Ireland, although it's rather low in the NE just as twilight ends 
in the evenings: it lies just above Castor.

So it should be possible to see some activity from about 18.00 onwards, 
increasing steadily towards midnight and the wee small hours. Then, depending on 
just when the peak occurs, it could continue at quite a high level almost to 
dawn, or gradually decrease again as the radiant gets lower in the West.

But if it's clear on Monday/Tuesday evening, head for a dark sky site and 
treat yourself to a real display of celestial fireworks - for free! Bring a 
lounger, or a waterproof rug or groundsheet + a foam mat & a sleeping bag; plus 
about twice as many layers of clothes etc as you think you'll need, especially 
for head, hands and feet; plus a hot flask of tea, coffee or soup (NOT alcohol), 
some choc bars or other sugar boosters; red & white torches, plus your mobile 
for security, and tell someone where you are going.

Ideally you want to be in a REALLY dark site, where the Milky Way is blazing 
down at you, and you can hardly identify the constellations because you can 
see so many stars! That means going at least 50 miles from Belfast & Dublin, 30 
miles from Cork, 20 miles from Bangor, Derry, Galway & Limerick, and so on pro 
rata for smaller towns.... Such sites are increasingly hard to find, and if 
you can't manage that, just go for a reasonable compromise, but you certainly 
should aim for somewhere that the Milky Way is easily vsible. If it's not 
visible, you'll see less than half, and maybe only a third, of the real number of 
meteors!

Your eyes won't fully dark adapt for about 20 mts, but you should start to 
see some meteors after at least 5 minutes or so, if the radiant is more than 
about 15 degrees up. Later in the night if it's totally clear & dark you could be 
seeing several meteors per minute, sometimes in bursts of 3, 4 or 5 in close 
succession, maybe followed by a short gap. 

Best place to look is at an altitude of about 45-50 degrees above the 
horizon, and about 40 degrees away from the radiant (no room to explain why!) in 
whatever direction the sky is darkest & clearest. The same applies to photography 
(use a standard 35mm camera, normal 50mm lens wide open (or closed down 1/2 or 
1 stop for better quality images), a fast colour film (ISO 400 - 800), and 
simply keep the shutter open for exposures of 6-10 minutes in a really dark 
site, or 3-5 minutes in a brighter one. You'll also need a tripod & a locking 
cable release (+ a spare just in case), and a red torch for checking the camera. 
DO make sure that the lens is set to your chosen aperture (NOT set at F/11 or 
F/16!), and make sure it's focussed on infinity! You should also bring some 
clean tissues for wiping dew from the lens (check it every other exposure)

The Geminids are a very interesting shower, as the 'parent body' seems to be 
an asteroid (Phaethon) rather than a comet; maybe this is why the Geminid 
particles seem to be denser than average shower meteors, and therefore often 
penetrate deeper into our atmosphere before buring up.

If you want to do some useful serious observing, record the sky limiting 
magnitude in the zenith, the times of each observing period to the nearest minute 
(e.g. 22.15 - 22.50; 23.00 - 23.28; 23.33 - 00.12), and the general sky 
conditions - any cloudy patches, or obscuration by buildings etc. Record the number 
of Geminids (+ any sporadics if you like, separately) seen in each observing 
period. Other useful information is the estimated magnitude of each meteor, the 
colour if any, speed (fast, medium or slow - most Geminids are slow), and any 
persistant trails (called 'trains') lasting more than a second or so after 
the meteor itself has disappeared. If you are observing with someone else, or in 
a group ONLY COUNT THE NUMBER OF METEORS YOU SEE YOURSELF! Anything else 
seriously distorts the calculated true (ZHR) rates!
(I can give more detailed advice on meteor observing if anyone wants.)

Otherwise, just stay warm & safe, and enjoy the show!

2. TV: the second programme in the 'Light Fantastic' series is on Wed 8 
December, at 21.00, on BBC4. It will be looking, inter alia, at telescopes & light.

3. The next Irish Astronomical Association Public Lecture will be on Wed 
December 15, when Dr John Butler of Armagh Observatory will give a talk entitled 
"The 2003 Restoration of Armagh Observatory" (If you haven't visited the 
Observatory recently, you should do so - quite a few changes, including one 
completely new dome, a unique 'Human Orrery', and major refurbishments! But first, 
come & hear this lecture, to get the full story.) It will be at 7.30 p.m., 
Lecture Room 5, Main Building, Stranmillis College, Belfast, with plenty of free 
parking. Free admission as usual and there will be some free seasonal 
refreshments as well!

4. IAA Xmas/New Year Party. This highlight of the discerning astronomer's 
(and the rest of you too....) social year will be at 7.30 p.m. on Saturday 8 
January, once again at the Tudor Private Cinema, just outside Comber, Co Down. The 
film will be "I, Robot", and there will be loads of eats & drinks of various 
alcoholic strengths (and none), plus a quiz & general good craic! We've had 
members (& visitors) from as far away as S Dublin & Limerick in the past, so it 
must be good! Admission only 10 per adult, plus special family rates too. 
More details, including directions, later, but mark your diaries now! 

Clear skies,

Terry Moseley

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