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From: TerryMoselaol.com
Date: 1 June 2006 23:26:51 BDT
Subject: Mercury, Visitors to the Beehive, BBQ, Eclipse photos.

Hi all,

1. If you have never seen Mercury, the Sun's closest planetary
companion, you should start looking over the next few weeks. Conditions
are not ideal, but it won't be too hard to find with binoculars, if you
know where and when to look. It will be visible in Ireland as an
'evening star' in the first 3 weeks of June, better seen the further
South you are. Greatest E elongation of 25* will be on 20 June, but it
will be fairly well placed for observing from about June 4 (magnitude
-0.6, elongation 18*), through June 22 (magnitude 0.6, elongation 25*). 
If you have a good clear NW horizon, you should pick it up in binoculars
about 30 minutes after sunset. DO NOT start looking for it while the Sun
is still above the horizon! With a telescope you might just see some
detail on the tiny disc: it's only 5.9" diameter on 4 June, phase 74%,
but it increases to 8.5" on 22 June, when the phase has decreased to

2. The lovely open cluster M44, also known as Praesepe, or The Beehive,
in Cancer will have two visitors this month. It lies about halfway
between Gemini and Leo, and is a beautiful sight in good binoculars or a
rich-field telescope. It is about 70 arcminutes across (just over 2 moon
diameters), and contains about 50 stars, the brightest ones being almost
6th magnitude. Saturn has just entered the Southern edge of the cluster,
and will pass across that edge over the next 5 days. Saturn is of course
much brighter than any of the cluster stars, at magnitude 0.4. But as
Saturn draws away from the SE edge of the cluster,  Mars closes in from
the West. On 6 June it will be only 5 degrees from the cluster and on
the evening of 14 June it will have reached its W edge. The most amazing
sight awaits us on the next evening, 15 June, when Mars is essentially
right in the middle of M44! It doesn't actually occult any of the stars,
as it is currently very far from Earth, and hence the disc is quite
small - only 4.1" across. It's also a lot fainter than Saturn -
magnitude 1.8, just a little brighter than Polaris. Next evening it will
be just off the E edge of the cluster. Unfortunately Mars and the
Beehive will be quite low in the W sky by the time it gets dark enough
to see them properly, so choose a location with a clear W to NW horizon.

You can look for Mercury while you are waiting for the sky to darken. On
the evening of 14 June it will be 20 degrees to the lower right of
Saturn (which will be the easiest object to see in that part of the
sky), at an angle of between '3.30' and '4.0' on a clock face. Saturn
itself will be just N of West as the sky gets dark enough to see it.
Next evening it will have moved about a degree closer to Saturn. Don't
confuse it with Pollux (Beta Gem), which will lie about 7 degrees above
and left of Mercury, and about 16 degrees right of Saturn, at about the
same altitude above the horizon as Saturn.

I attach a JPEG chart of their positions at 11 p.m. BST on 15 June. The
chart is for Belfast, but it will be close enough for anywhere in
Ireland. The azimuth and altitude grid is shown: 270 degrees is due
West, 315 degrees is NW.

3. IAA BBQ: Don't forget the social and culinary event of the year: the
IAA's midsummer BBQ at Armagh Observatory on Sat 2 June. We start at 3
p.m. with some activities (details later), followed by cooking & eating
at about 5 p.m. You bring your own food, drink, eating equipment etc; we
provide the heat on which to cook.

4. Eclipse Photos: The June issue of Astronomy Now has superb photos of
the total solar eclipse by IAA member David Stewart, and by David Rayner
who was also with us on the IFAS eclipse trip to Turkey. Well done.

Clear skies,

Terry Moseley


Last Revised: 2006 June 2nd
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