Monday, 7 September 2009

Symposium, Lectures, Mutual Jovian satellite event, Open Day, Art, BSP.

Hi all,


Another reminder about the major European Light Pollution Symposium in Armagh on 17-19 September. (I've sometimes referred to it as a conference - it's the same event!)

There are some excellent speakers, on all aspects of the subject, as well as the latest information on what we can do to reduce the problem.

I'm sure many of you are planning to go, even if only on the Saturday, and/or for the trip to the Beaghmore Stone Circles & Alignments on Friday evening, which includes a meal at the An Creagan Centre, and, if clear, observing in one of the darkest sites in N.I.

But we need to know how many will be attending on each day, so that we can plan catering, transport, etc, so if you have not already done so, PLEASE REGISTER NOW on


As part of the symposium, well known science broadcaster & journalist, Leo Enright, will give two free keynote public lectures, entitled "What is Light?" He will explore the history of Ireland's sometimes tenuous connection with luminosity, while naming and shaming some modern big wicks. Leo adds: "Expect some terrible puns and some spectacular new images of Ireland from outer space".

The first of these free public lectures is in Dublin at the Royal Irish Academy (see at 7.00pm on Wednesday 16th September.

The second (a repeat of the first) is at the Market Place Theatre, Armagh, at 7.30pm on Thursday 17th September. If you wish to register for the Armagh public lecture, please contact Aileen McKee at the Armagh Observatory (E-mail: ambnat; Tel: 028-3752-2928).

Here are the details again about the main part of the conference itself:


ILPAC, the Irish Light Pollution Awareness Campaign, was asked to host this year's

European Symposium for the Protection of the Night Sky. This is an annual event held in a different country each year and is the main gathering of light pollution experts from around Europe with some speakers also coming from the USA and Japan.

Thanks to the help of Discover Science and Engineering and Armagh Observatory we have put together a great programme of talks that I'm sure you'll find interesting. And in addition to the main event we have free public lectures by Leo Enright in Dublin and Armagh. (You

need to register for these free talks by the way - details on the website . There will also be excursions to Armagh Planetarium, An Creagan visitor center and the archaeoastronomy site at Beaghmore stone circles for some dark sky observing if clear.

You can see the symposium program, biographies of the speakers and other details on the website. Also pass this on to your colleagues. And if any of you have had dealings with elected council officials or county lighting engineers please tell them to come along. We will have experts in lighting and campaigners who have worked to get better lighting policies

implemented with local town councils to EU and USA federal level who will be happy to help councillors see the benefits of better lighting policy.

Please register as soon as possible so that we know how many to arrange catering and transport for. €30 for the weekend, €20 for either the Friday or Saturday. See

4. IAS LECTURE. September 7, 20.00: The first talk of their new lecture season will be held in Dunsink Observatory, Castleknock, Dublin, at 8pm. John O'Neill will recount his trip to China to view the total solar eclipse of 22 July.

5. MUTUAL JUPITER SATELLITE EVENTS: There are two mutual events involving Io and Europa on the night of 8 Sep (Tue-Wed). First, Europa will be occulted by Io between 23:22 and 23:32 BST, and this will be followed by Io eclipsing Europa between 00:38 and 00:47 BST. Jupiter will be reasonably well placed low in the southern part of the sky as seen from Ireland.

The occultation is partial, with 55% of Europa (magnitude 5.3) being covered by Io (magnitude 5.0). With smallish telescopes, and/or poor seeing, the two satellites will just seem to get closer together until they appear to merge into one brighter satellite (like an unresolved double star), with a combined magnitude of 4.4. With medium sized telescopes, and/or middling seeing, you might see the two moons as a single but elongated object. Then as the occultation begins, the magnitude will begin to drop fairly quickly, as over half of Europa's bright surface is hidden by Io. And in a powerful telescope, with good seeing, you can watch as one disc passes partly in front of the other. But for most of us, what we'll see is the convergence of the two moons, their apparent merger into one body, perhaps elongated, with the corresponding increase in brightness, then the decrease as one body partly hides the other one, then all that will happen again in reverse.

The nominal magnitude decrease will be about 1.0 magnitudes, i.e. to 6.3, but that applies to the magnitude of Europa alone - if the seeing is so poor that you have only been able to see them as a single unresolved object, then the magnitude drop will be from 4m.4 (the combined magnitude). In other words, in mid-occultation you'll be seeing all the light from Io, plus about half the light from Europa.

The eclipse is also a partial, with 53% of Europa being eclipsed, resulting in a flux drop of 63%, which is equivalent to a drop of 1.07 magnitudes. This is enough to be noticeable by eye by careful comparison with the brightness of the other satellites.

During both these events, all four Galilean Moons will lie on the East side of the planet, with Ganymede (mag 4.6) and Callisto (mag 5.6) further out in that order. At the time of the eclipse Io will be closest to the planet, then Europa, then Ganymede & Callisto. The separation between Io and Europa will be 16" (arcseconds) at the start of the eclipse.

6. Astronomy Ireland Lecture: September 14: "Searching for exoplanets: modern methods and future prospects" by Dr. Christopher Allan Watson, Astrophysics Research Centre, Queen's University Belfast. More details at

7. Art Exhibition: September 18th: A major exhibition collated by Deirdre Kelleghan will launch at Birr Castle, County Offaly. Entitled "In the Footsteps of Galileo", it will feature drawings and sketches of the Moon created by Irish, American, and many more children along with lunar, solar, planetary, and deep sky sketches made by well known observers and artists such as Sir Patrick Moore, Sally Russell, Jeremy Perez, Sue French, Dan Davis, Jeff Young and many more. More details on

8. IAA PUBLIC LECTURE: 23 September. The opening lecture of the Irish Astronomical Association's new season will be given by Prof Tom Ray of the Dublin Institute of Advanced Studies and the Royal Irish Academy. It is entitled "Planning Hubble's Successor, the James Webb Space Telescope". Prof Ray is eminently qualified to talk on this topic, as he is involved in the design of some of the instrumentation which will be going on the telescope! We have had several excellent lectures from Tom before, and we are delighted to welcome him back again. It's on WEDNESDAY 23 SEPTEMBER, at 7.30 p.m., in the Bell Lecture Theatre, Physics Building, Queen's University, Belfast. ADMISSION IS FREE, as always, and includes light refreshments. Everyone is welcome. Full details of the rest of the programme are on the website:

9. ARMAGH OBSERVATORY OPEN DAY: As part of the Heritage week events, Armagh Observatory will be open free to the public on Saturday 12 September, with tours planned for 11.00, 12.00, 14.00, 15.00 and 16.00. See for further details.

10. The BURREN STAR PARTY organised by the Shannonside Astronomy Club (replacing the Whirlpool Star Party, at least for this year), will be held on 26 September at the Burren Coast Hotel, Ballyvaughan, Co Clare. More details on

Clear Skies,

Terry Moseley


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