time on the morning of Wednesday 6 June. During such a transit, the planet Venus passes directly between the Earth and the Sun, appearing as a small black circle taking several hours to cross the Sun.
This year's transit is the last visible from Earth for more than a hundred years. The exhibition to mark the event comprises items relating to the history of transits of Venus including items from the Observatory's
archives and the King George III Collection. Further details can be found at the web-site http://star.arm.ac.uk/venustransit/exhibit/.
The exhibition will be open, free of charge, from 10:00--11:00 and 15:00--16:00, Monday to Friday, from Friday 1 June to Tuesday 12 June inclusive. Groups of more than six persons are requested to contact the
Observatory in advance: Tel: 028-3752-2928; E-mail: firstname.lastname@example.org.
3. The TRANSIT OF VENUS, 6 June: This is the last Venus transit visible anywhere in the world until 2117. Transits usually occur in pairs separated by 8 years, with a gap of over a century until the next pair; the first one of the present pair occurred in 2004. However, 'single' transits do rarely occur: the next one will be in 3089, i.e. there will be none in 3097. It is the most central transit since 1639, with Venus passing 9' 13" from the centre of the Sun at mid-transit at 01.28 UT (that moment is not visible from Ireland, as the Sun will still be below our horizon), and that record won't be exceeded until 2255.
The apparent diameter of Venus during the transit will be 57.8" (arcsecs); just below the limit for naked eye visibility, so some sort of optical aid will be required. NOTE: All the usual safety advice applies when observing this transit: i.e. do NOT look at the Sun directly with anything except proper solar filters on either telescope or binocs, or by projecting the image through a telescope on to a piece of white card. See www.irishastro.org for details.
The following times are given in BST. Time of 3rd Contact in N. Ireland = 05h 37m 03s. Time of 4th Contact (end of the transit) = 05h 53m 14s. The effects of refraction on both the Sun's and Venus' altitude and the various timings have been taken into account.
NB: Sunrise is the time when the upper limb of the Sun first comes above the theoretical horizon. But the transit will not start to become visible at this time, as Venus will be a bit below the upper limb of the Sun. So to calculate the visible duration, we must start from the time of 'Venus rise', not sunrise. Venus will transit across the N third of the Sun's disc, and will be exiting at the NW (top right) of the disc, after which it will cease to be visible.
OBSERVING SITES: I have checked about a dozen possible observing sites in NE Co Antrim, with the recommendation below. (Skerries, Co Dublin, is in effect the best site in ROI, although the tip of the Cooley Peninsula is marginally better than Skerries, but not enough to justify a long journey).
Note also that the time of first visibility of the Sun and Venus will depend on the altitude of the actual local NE horizon. For sites near Fair Head and Torr Head, that's the Mull of Kintyre in Scotland, (reaching 446m above sea level), and beyond it the Isle of Arran, which reaches 874m. So actual local sunrise from those sites will be delayed by several minutes. Those mountains might also attract a covering of cloud, delaying visibility of the Sun and Venus by several minutes, or even longer.
APPEARANCE ON THE SUN'S DISC: Venus will appear in the NE sector of the Sun's disc. At the moment of Venus rise it will be about 1/10 of the Sun's diameter from the Sun's limb. From then on that distance will decrease as the transit progresses to its end.
OBSERVING SITE: All factors considered, the best option seems to be Garron Point, between Carnlough at Glenarriff/Waterfoot, where there are two suitable car parks within 0.2 miles, with the option to move to the higher site at nearby Tower Rd if there is a sea fog. NB: There is no car park on Tower Road, but there are two areas where one could park safely along the roadside (as there will be no traffic there at that time of the morning), with clear views to the NE: these are at 0.9 miles and 1.0 to 1.1 miles from the junction of the south end of Tower Road with the main A2 road. This is at N55˚ 01' 49", W 5˚ 58' 21", 3.5m N of Ballygalley Castle Hotel.
WEATHER: Apart from the risk of cloud, there is also a slight chance of a sea fog. All the sites along the A2 coast road are vulnerable to that. Two suitable higher sites are available: Tower Road, above Garron Point (alt 70m), and the car park at the summit of Ballycoose Rd, above Cairncastle (alt 270m).
TIME: If you want to set up cameras and/or a telescope, you should be ready to image / observe by about 04h 40m – 04h 45m BST, so arrive in plenty of time. Orient your instruments to the NE (approx. azimuth of 46˚), and look for the first glimpse of the Sun. Look 20˚ left of Ailsa Craig (a prominent conical island on horizon).
EATS: We will celebrate (or commiserate if cloudy) with a fry-up at the site after the event, so bring some suitable grub, plus a portable BBQ or gas stove, frying pan etc.
7. A BRIDGE FOR PHYSICS: "The Walton Bridge petition". The Institute of Physics (IOP) Ireland is campaigning to have the new bridge across the Liffey in Dublin at Marlborough Street named for ETS Walton - Ireland's only physics Nobel prize-winner. Please sign our petition to Dublin City Council via the link at http://www.iopireland.org/news/12/page_55296.html. (via Peter Gallagher)
The programme for the event is currently being finalised and will be updated in due course on the IFAS website www.irishastronomy.org However, the event will feature a number of lectures, a workshop, solar observing (weather permitting) and more. The lunchtime break will allow an opportunity to take in a tour of the facility to see the observatory and the 12" Grubb refractor. Tea/coffee will be provided, however please bring your own lunch.
Spaces are limited to 60 seats. If you are interested in attending, please send an e-mail to email@example.com. Please state in the e-mail how many seats you would like to reserve.
Regards & Thanks, Michael O'Connell
(NB: Dunsink Observatory is on Dunsink Lane, Castleknock, Dublin. The Observatory is at 53 deg 23' 14.3"N, 6 deg 20' 19.0" W, with the entrance off Dunsink Lane at 23' 16.6"N; 20' 14" W. But Dunsink Lane has been blocked on the city side, and the observatory is now only accessible from the New River Road end, off the Navan Road, near the junction of the N3 and the M50 - the Castleknock junction, Junction 6. Since the M50 upgrade this has become a very complex junction.
If approaching via the M50 from the Dublin airport direction, you MUST get into the correct lane at the offslip, or you'll be way off course! So when you approach Junction 6, move onto the offslip lane (to the left, obviously), but then stay on the two right hand lanes of the offslip, signed for 'Castleknock'. Do NOT keep on going round to your left via the left hand lane on the offslip, which will take you on to the N3 and Castleknock village! (That seems wrong when you know where Dunsink is, but believe me - I learned the hard way! If your Satnav says something else, ignore it.)
Then move into the left hand of the two 'right' offslip lanes (in other words, the middle one of the three). This will bring you to the original roundabout, with traffic lights, where you then keep left, and then immediately left again, signed for 'Dunsink'.
This road leads directly on to New River Road. At the 'cul-de-sac' sign continue on straight, and it becomes Dunsink Lane. Go straight on for almost 2 km (past Elmgreen Golf Course) until you see the road blocked ahead of you: the entrance to the Observatory is on the right just before the block.
If you go this way, it's simple and easy, so don't be put off - just follow those directions exactly.
On the return journey you go back along Dunsink Lane, then follow signs for the M50 Northbound. (TM)
9. TWITTER: the IAA now has a twitter account. twitter@IaaAstro