Email. Eclipse. Aurora. I.S.S. Banking. Join the Team 1. The computers that host astronomy.ie had a problem on Wednesday night and much of Thursday. We are assured this is a rare occurrence and all seems to be well now. If you sent email to info@astronomy.ie or subscribed online your email probably bounced back saying "no such user". Ignore this. We are, in fact, alive and well! During all this, our website http://www.astronomy.ie appeared to be working fine. Our apologies for any inconvenience caused. 2. ECLIPSE MAY 31 5am: In the meantime this gives me an excuse to remind you about the partial eclipse of the Sun coming up early on Saturday morning. The weather forecast looks good, and it will need to be as the Sun will be at maximum eclipse when it is on the horizon at sunrise as seen from Ireland. The table below may look a bit complicated but just work through it as follows: About 92% of the Sun (92% of its diameter that is) will be covered just before it rises. That means the morning twilight will only be generated by a very weak Sun (almost totally eclipsed!) so it could be quite an eerie experience before sunrise. I am expecting that it will be possible to see bright stars in a weak twilight almost until sunrise? Mars in particular will be very bright in the southeast at magnitude -0.7. The Sun rises in the northeast of course. The 'summer triangle' (Vega, Deneb, Altair) will be high overhead. In the table below, in the column headed "Max/%/alt" I have given "Max" as the time of maximum eclipse (even though the Sun will be out of view below the horizon), "%" the percentage of the Sun's diameter covered by the Moon at that time, and "alt" the altitude in degrees of the Sun at that time. Try to view 15 to 30 minutes before this time and let us know what you see (email observe@astronomy.ie) Then comes "Sunrise". This is the instant at which the top tip of the Sun peeks above the horizon, allowing for refraction i.e. it is the real time you should expect to see anything of the Sun. Of course, it assumes a perfect horizon like you really only get at sea. If you have mountains, hills or any other obstacle in the distance you still won't see the Sun at this time. However, if you can get up on a height (hill or mountain) you may be able to see the Sun even before this - don't forget though that there has to absolutely no cloud on the horizon and any mist or haziness will dim the Sun significantly at this low altitude. I have included the percentage of the Sun's diameter covered by the Moon at this time. The Moon takes a 'bite' out of the left side of the Sun so this 'bite' won't yet be visible as the top of the Sun has only peeked over the horizon at this time remember. Under "FullSun" I have given the time when the bottom edge of the Sun is now sitting on the horizon. At this time the entire solar disk is visible (assuming a perfect horizon remember). The percentage of the Sun's diameter covered by the Moon is also given. This is the same as the diagram on my editorial on page 4 of the June issue of our magazine (http://www.astronomy.ie/sub) [Aside: for the diagram in the magazine for Dublin I used a slightly less accurate computer program that gave 51%. The correct figure is 46% as per the table below which is very accurate having been calculated using professional astronomers' data.] Finally, I give the end of the eclipse "Ends", when the Moon finally moves off the Sun's disk and the eclipse is over. We then have to wait 2 years 4 months for the next partial eclipse of the Sun visible from here. All times give are summer time (BST) (View or print this table with a mono-spaced font like 'courier') Location Lat/Long Max/%/alt Sunrise FullSun Ends Belfast 54.6N,5.9W 4:43am/93%/-2.2 4:57am/72% 5:02am/64% 5:39am Birr 53.1N,7.9W 4:43am/93%/-4.2 5:14am/43% 5:18am/35% 5:38am Cavan 54.0N,7.4W 4:43am/93%/-3.2 5:06am/56% 5:11am/48% 5:39am Cork 51.9N,8.5W 4:42am/92%/-5.4 5:22am/25% 5:27am/18% 5:37am Derry 55.0N,7.3W 4:45am/93%/-2.4 5:00am/70% 5:05am/61% 5:41am Dublin 53.3N,6.3W 4:42am/92%/-3.4 5:06am/54% 5:11am/46% 5:38am Dundalk 54.0N,6.4W 4:43am/93%/-2.9 5:02am/62% 5:07am/54% 5:39am Galway 53.3N,9.0W 4:44am/93%/-4.4 5:17am/38% 5:21am/31% 5:39am Limerick 52.7W,8.6W 4:43am/93%/-4.7 5:19am/34% 5:23am/26% 5:38am Sligo 54.3N,8.5W 4:45am/93%/-3.4 5:09am/54% 5:14am/45% 5:40am Tralee 52.3N,9.7W 4:43am/92%/-5.4 5:25am/23% 5:29am/15% 5:38am Waterford 52.3N,7.1W 4:41am/92%/-4.6 5:15am/38% 5:19am/30% 5:37am SAFETY: Never look directly at the Sun without proper filters. You can still get Eclipse Shades from Astronomy Ireland and the AstroSolar filters for your binoculars and/or telescopes. You can project an image through binoculars or small telescopes but supervise such telescopes at all times and don't let heat build up and damage your optics. In an absolute emergency you can get a crude image by punching a hole in a piece of card with a pin and picking up the sunlight passing through the pinhole on a piece of white paper held a few inches away. Further details of the eclipse are on pages 28-29 of the May issue of Astronomy & Space magazine, and page 4 of the June issue. Good luck with the weather and do go out up to an hour before sunrise and let us know if the twilight is unusual that morning. 3. AURORA - a display of the Northern Lights, or aurora borealis, has been predicted for tonight Friday night. Keep an eye on the Northern horizon all night long. Check tomorrow night too. There are nice sunspots on view at present - yet another reason to get your sheet of AstroSolar from our Shop. 4. I.S.S. - Don't forget you can see the International Space Station blazing across the sky tonight, and every night until next Wednesday with Ed Lu and Yuri Malenchenko on board. Call our premium rate Newsline every day after 12noon for the time to see I.S.S. later that evening: 1550-111-442 (calls cost 74c/min). Those in U.K. can call 09001-88-1950 (calls cost 60p/min). Tell your friends! 5. BANKING - We want to set up a new direct debit system for the club but we are having some problems. If you are involved in banking can you email David Moore at info@astronomy.ie please? 6. JOIN THE TEAM - we are seeking more people to get involved in the running of Astronomy Ireland. If you think astronomy in Ireland is an important issue then please get in touch, be it promoting interest to the general public, in schools, or to government, there is a lot to do and we need people who feel passionately that things like the recent removal of astronomy from the Junior Cert syllabus should not go unaddressed by the national astronomy society. Or what about the fact that Irish professional astronomers now have no access to cutting edge telescopes with the loss of the La Palma telescopes - public support could help here. Or maybe you just want to help organise more events around the country, or you have other ideas of your own. These are the sort of issues we need to address, not just the internal running of our Society for its members (though this is of course our prime concern). Email info@astronomy.ie if you want to get involved in any way at all. ===== David Moore BSc FRAS, Chairman, Astronomy Ireland, P.O.Box 2888, Dublin 5. Editor, "Astronomy & Space" magazine. ASTRONOMY SHOP: open Mon.-Fri. 9:30am-5:30pm and Sat. noon-6pm. Tel (01) 847 0777. Fax (01) 847 0771. WWW: http://www.astronomy.ie (Subscribe FREE to AI's Events emailing list) Email: info@astronomy.ie