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MEETINGS

COMMITTEE MEETING Members of the Committee are respectfully reminded that there is a meeting of the Committee at Jim’s house starting at 1930 on Tuesday the 9th of April.

MARCH MEETING The March meeting was opened by Phil Berry who welcomed the Vernal Equinox and the start of spring. As mentioned in the March Newsletter, there is a proposed Observing Evening on the 25th of March on Ashdown Forest under the direction of Ian McCartney, and if the weather is not suitable, then there is a standby on the following day. A list was at the rear of the room for interested members to fill in. This event has obviously taken place and was a success. There is a report later in the newsletter. Nicki Charnick has kindly donated a book to the library that contains six CDs. Nicki said they were slightly out of date but still very interesting. Finally Phil introduced our speaker William Joyce whom he gladly welcomed back for another of his fascinating talks. The Search for intelligent life in Deep Space William Joyce FRAS Before starting his talk William said he had learnt that within the next two weeks, new images of Ultima Thule are due to be released and information could also include new interpretations and is worth keeping an eye open. First he showed us an image of the whole night sky, which showed the Milky Way and included the Large and Small Magellanic Clouds towards the bottom right.

It was once thought that our galaxy was about 100,000 light years across, but it is now known to be at least 150,000 light years across and could be more. One of the big questions is “is there intelligent life out there?”

Wadhurst Astronomical Society Newsletter April 2019

The whole Night sky showing the Milky Way and includes the Andromeda Galaxy and the two Magellanic Clouds

NASA

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Using the Scientific Method we define life as life as we know it here on Earth. So William talked about the possibility of there being life in other parts of the Universe. We looked at the Orion Nebula as an example of a possible source of life.

He described the gaseous region as the birthplace for new stars and is ever changing and with that the brighter stars becoming supernovae, exploding and creating yet more material for future star formation. In passing, we were told an interesting fact that in a cave painting some 17,000 years old, another star was shown in the Orion constellation but it no longer exists, indicating just how things are continually changing. William introduced us to Astro-biology, which is the study of matter holding the origins of life. It is known that life was mostly bacteria for 3 billion years on the Earth and it is only in the past half-billion years that more advanced life has developed. Then there is the question of advanced life elsewhere in the Universe and would we be able to detect it? Life on Earth requires carbon and liquid water and we were told that if life is found else where, it is unlikely to look anything like us but would depend on its environment. We briefly looked at Silicon as another possible basis for life, but William said it was far less stable than carbon, which is the basis for our life form. Life doesn’t necessarily rely on the Sun; in fact on Earth, Extremophiles are life forms that live in extreme temperatures on the floor of the oceans where hot gasses vent out into the bottom of the sea. An even more extreme life form we were told about is the Tardigrade.

Tardigrades are less than a millimetre across. They can survive in a vacuum, at almost zero Kelvin, in an atomic reactor and they can even survive without water for ten years or more. They could even survive transport through space. The Earth is in what is called the ‘Habitable Zone’ where the temperature right now is suitable for liquid water but William said that as the Sun evolves, so the temperature on Earth will increase until life can no longer exist and after a time, Mars will be in the habitable zone.

The Orion Nebula containing gases where new stars are being born apod NASA

The Tardigrade is an almost

indestructible life form

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A star smaller than the Sun will have a much longer life and the habitable zone would be closer. A brighter larger star would have a shorter life and the habitable zone would be that much further away. So there are a very limited number of exo-planets that would be suitable for life. Following studies of stars near to the middle of our galaxy it is thought they would be affected by radiation from the black hole at the centre and we were told that it is unlikely that life could exist here. Also some scientists think that there is too little carbon, iron and other heavier elements in stars near the edge of the galaxy for planets to form and so life there would also be unlikely. William now looked at how we go about looking for information from objects in space. Imaging is one way, and telescopes are becoming very large. There is one called the BIG telescope in La Palma with an 11-metre diameter mirror. With these large telescopes it is hoped to learn about atmospheres around exo-planets. More information can also be learnt from looking at the absorption lines in a star’s spectrum.

A lot of information is found from absorption lines, such as temperature, isotopes present and pressure and much more. New techniques are being developed to measure the atmosphere of some exo-planets. If it is possible to examine the atmosphere of an exo-planet and it is found to contain water and carbon, it only needs ozone in that atmosphere to confirm that there is oxygen present. It was explained that the presence of enough ozone can form a stratosphere layer and the presence of this stops convection currents that would otherwise carry water vapour out into space and it would be lost. The Extra Big telescope being built on Chile will have a 39-metre mirror and this William said should enable scientists to learn more from exo-planet atmospheres. TESS, the Transit Exoplanet Survey Satellite has replaced the Kepler space telescope, which concentrated on looking for exo-planets in a very small part of the sky whereas its replacement is looking at the whole sky, and it is expected to detect a considerable number of exo-planets. Trappist-1 is a Red Dwarf in the constellation of Aquarius, which has been found to have seven planets, three of them in the habitable zone. Radio telescopes can contribute to mapping the galaxy using hydrogen, which emits radio waves on a wavelength of 21cm. One radio telescope used to search on the 21 cm wavelength is the Large Arecibo telescope in Puerto Rico, which has also been used to ‘listen’ to radio emissions from other stars and William said it has often been used for SETI searches. SETI is the Search for Extra Terrestrial Intelligence. Now a number of SETI searches are being carried out; one by the Allen telescope in California, dedicated just to search for radio signals.

An image of HR8799 where it is now possible to see planets apod/NASA

Spectrum of our Sun with absorption lines from which can be learnt a lot about

chemical composition and more NASA

The Allen Telescope Array in California

dedicated to the search for radio signals and

run by the SETI institute.

So far no signals have been found.

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Even the most powerful radio signals transmitted on Earth would be too week to be detected very far away, but if a signal was beamed from Arecibo in just one narrow beam in one direction it would be capable of being detected at interstellar distances. Frank Drake is an American astronomer who worked on the SETI programme, partly at the Arecibo observatory. In 1961 he devised what is known as the Drake Equation to estimate the number of active, communicative extra-terrestrial civilisations.

𝑁!"# = 𝑅∗ × 𝑓! × 𝑛! × 𝑓! × 𝑓! × 𝑓! × 𝐿 Where: 𝑁!"# =number of civilisations in our galaxy with which communication might be possible𝑅∗= the average rate of star formation in our galaxy𝑓!= the fraction of those stars that have planets

𝑛! = the average number of planets that can potentially support life per star that has planets𝑓! = the fraction of planets that could support life that actually develop life at some point𝑓! = the fraction of planets with life that actually go on to develop intelligent life (civilisations)𝑓! = the fraction of civilisations that develop a technology that releases detectable signs of their existence into space 𝐿 = the length of time for which such civilisations release detectable signals into space. William said that we already know that the first three terms in the equation are equal to one, and then if the rest of the terms equal one then the number of civilisations would equal L. He said that if we were really pessimistic we could end up with just one civilisation, but not less than this because we would be that one. There is a thing called the Fermi Paradox which considers that there are billions of stars and probably planets in the galaxy, so where is the evidence of alien existence? If just one is found, this ceases to be a paradox. It may be impossible to travel between interstellar distances, or perhaps there are ethical codes that prevent communication. We have been sending coded plaques aboard spacecraft such as Pioneer 10 & 11, which contain information about ourselves. Even a gold plated record was sent aboard Voyager, which also had a diagram showing how to build a record player. Finally, William said that once a primary sun has become unstable and the habitable planets unable to support life anymore, civilisations might build a spacecraft to carry living beings to look for somewhere else in the universe to colonise. If this had been happening, through billions of years, other colonies should have established themselves, but so far there is no evidence of them, and this is called the Fermi Paradox. Project Daedalus was a study by the British Interplanetary Society to design an unmanned spacecraft using current nuclear fusion technology to explore a nearby star that can be reached in about 50 years. Considered to be the most credible spaceship for the purpose of recolonizing elsewhere is the one designed for use in the film Avatar.

It is many miles long and would to be prepared to last thousands of years. William’s last comment was that if we were to find somewhere where that would appear suitable, we would have to actually go there to really find out if it was possible to survive there…

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Following the break, Brian Mills continued his talk about suitable astronomical telescopes. Astronomical Telescope Mounts Brian Mills FRAS Last month, Brian described a number of telescopes available to the amateur astronomer and this month he tells us about the different mounts there are to support them. To be useful a mount has to be rigid and we need also to consider a number of other things. Since it appears that the stars are in constant motion and don’t move in a straight line, we have a problem when we want to study an object over a period of time. So a prime consideration is what the scope is to be used for. The first mount Brian introduced us to was the Alt-Az (Altitude – Azimuth) mount.

There are two axes of rotation, horizontal and vertical. With this mount the telescope can look at any point in the sky, but if we want to look at something over a period of time, we would require the mount to follow a gentle arc by re-adjusting it frequently. To get around this we need an Equatorial mount that allows the telescope to follow the motion of the stars.

Once the mount is lined up with the celestial pole, the telescope will follow the direction of movement of the stars. Brian said that this is called Right Ascension. The vertical motion is called the Declination. A common and very simple mount is the Dobsonian mount. It is an Alt-Azimuth type and is often favoured by amateurs who wish to build their own mount.

The straightforward Alt-Az mount

The Equatorial mount with the mount axis

directed to the Celestial Pole, which is close to the star Polaris in the

northern hemisphere and the plane of rotation at

the angle of latitude

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Another type of Alt-Azimuth mount Brian spoke of was the Fork mount where the telescope sits in a fork that moves horizontally and vertically. To enable an Alt-Aziuth mount to follow the motion of the stars there is an adaptor wedge.

A Dobsonian mount with a reflecting telescope

Some Dobsonian mounted telescopes can be very large

An example of a Fork mounted telescope

To convert a fork to an equatorial mount, there is a wedge available

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The next mount Brian introduced was the German Equatorial mount, which is driven and rotates at the correct rate in Right Ascension.

To support the mount it is placed on either a tripod or pillar. We were told that either must be stable to be useful in astronomy. Here are two portable variations.

The last mount Brian described was the Permanent Pier. If serious astro-photography is intended, then the mount needs to be on the most stable base possible and here is an example of a concrete permanent pier.

The base is buried permanently in the ground.

A German Equatorial driven mount

The tripod and the pillar support are both portable but when moved, the telescope will still require realigning

A concrete pier set in a substantial concrete base

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APRIL MEETING

17 April 2019 – One of our members, Doug Edworthy, gives a multi-media presentation entitled “The Universe Through the Internet” Meetings will take place at Uplands College, Lower High Street, Wadhurst and are held in classrooms IL5 and IL6, which are in the blue walled classroom block at the far end of the drive from the main gate and up by the tennis courts. Signs will direct you. There is car parking near the block although this needs to be cleared before 2230 when the main security gates close. The Post Code is TN5 6AZ, Meetings begin at 1930 prompt although members are invited to arrive anytime after 1900, as this is a good time to exchange ideas and discuss problems and also help set things up before the meeting starts. Anyone is welcome but visitors are asked for a small fee of £3.

FUTURE MEETINGS 15 May – We welcome back Colin Stewart who talks about “How we’ll live on Mars” 19 June 2019 – Brian Mills FRAS asks “How Did We Get to Where We Are?” 17 July 2019 – TBC There is no August meeting 18 September 2019 - TBC 16th October 2019 – TBC 20th November 2019 - TBC

SKY NOTES FOR APRIL Planets Mercury passed through inferior conjunction in mid March and is now a morning object although this elongation will not be a favourable one. The smallest planet moves west of the Sun to reach greatest elongation on April 11th when it will, in angular terms, be 28° from our parent star. This is the furthest apart that the two bodies can be seen, but in the UK we will not be able to take advantage of this. The cause is the angle that the ecliptic makes with the horizon at this time of day/year. Even on the 11th Mercury rises just 30 minutes before the Sun, which means that at the beginning of civil twilight, the planet is still below the horizon. At the time of elongation its magnitude will be +0.4 so it will be a difficult object 5° above the eastern horizon as the Sun rises. Venus is also visible in the morning skies rising a little earlier than Mercury although the position of the ecliptic hampers visibility once again. In addition to this Venus moves a little further south of the ecliptic during April although is greater brilliance makes it an easier object to locate. Despite that advantage, the current apparition is drawing to a close particularly for those of us observing from the latitudes of the UK. Venus rises an hour before the Sun at the start of the month but this has shortened to just over 30 minutes by the end. Following this it will be extremely difficult to find in the solar glare. Mars continues its long tenure in the evening skies and as the month begins it is due west at 21:00 with an altitude of almost 30°. The red planet is moving direct (eastwards) through Taurus, passing roughly midway between the Hyades and Pleiades on the 4th/5th/6th of the month. On the 26th Mars passes through the 6th magnitude open cluster NGC 1746. There will be no opposition of the planet during 2019, nor does it travel retrograde at all during this year. However, it is still decreasing in both brightness (magnitude +1.6) and apparent size (4.2 arc seconds) by the end of April. Fig 1 shows the position of the planet relative to the stars in Taurus at 5 day intervals, although don’t forget that the position of the constellations relative to the horizon will change as the month progresses.

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Jupiter is still a morning object although it rises 4½ hours before the Sun at the start of this month. This means that at the start of April it rises at 02:00, but by the end it is on the horizon at midnight. By the middle of May it should become visible low down in the southeast around midnight. The gas giant remains in the southern part of Ophiuchus moving direct (eastwards) until April 10th when it reaches its first stationary point after which it assumes retrograde motion. The planet is moving towards a June opposition so its magnitude creeps up from -2.2 to -2.4 and it equatorial diameter rises from 39.5 to 43.5 arc seconds in anticipation of this. Fig 2 shows Jupiter’s position at 05:00 mid month as it culminates (crosses the meridian due south).

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Saturn is also a morning object though it rises a little later than Jupiter at around 03:30 at the beginning of the month. It too is approaching opposition, though in Saturn’s case it will take place in early July. The ringed planet will move direct in Sagittarius until the last day of April when it reaches its first stationary point after which, it too, moves retrograde. Fig 2 shows the position of Saturn in the early morning skies, mid month. The planet’s axis remains tilted towards Earth by approximately 23° providing excellent views of the ring system. Lunar Occultations In the table below I’ve listed events for stars down to magnitude 7.0 that mostly occur before midnight although there are many others that are either of fainter stars or occur at more unsociable hours. DD = disappearance at the dark limb, RD = reappearance at the dark limb and RB = reappearance at the bright limb. The column headed “mm” (millimetres) shows the minimum aperture telescope required for each event. Times are in BST.

April Time Star Mag Phase % illumination mm 9th 22:32 ZC 718 6.0 DD 20 40

9th 23:27 ZC 726 6.9 DD 20 70

10th 23:41 SAO 77516 6.9 DD 30 60

13th 20:19 ZC 1287 6.7 DD 62 60

13th 21:45 ZC 1297 6.8 DD 62 70

14th 20:05 ZC 1418 5.7 DD 73 50 Phases of the Moon for April

New First ¼ Full Last ¼ 5th 12th 19th 26th

ISS Below are details for evening passes of the International Space Station (ISS) this month where its brightness is -1.0 or above. The details of other passes, including those visible between midnight and dawn, can be found at www.heavens-above.com. Please remember that the times and directions shown below are for when the ISS is at it’s maximum elevation, so you should go out and look at least five minutes beforehand. Times are in BST.

Apr. Time Mag. Alt° Az. Apr. Time Mag. Alt° Az. 1st 20:50 -3.9 82° SSW 4th 21:31 -2.0 21° SW 1st 22:25 -1.3 17° WSW 5th 20:40 -2.4 31° SSW 2nd 21:36 -3.0 38° SSW 6th 21:25 -1.1 11° SW 3rd 20:45 -3.4 54° SSW 7th 20:35 -1.4 17° SW 3rd 22:20 -1.0 12° WSW

Iridium Flares Below are the only two evening predictions for bright Iridium flares this month. These predictions are location specific so if you wish to see a complete list, or obtain timings for somewhere other than Wadhurst go to www.heavens-above.com. When one of these events is due, it is sometimes possible to see the satellite before and after the “flare” although, of course, it will be much fainter then. Times are in BST.

Apr. Time Mag. Alt° Az. Apr. Time Mag. Alt° Az. 6th 22:47 -1.4 10 27° (NNE) 30th 23:02 -3.1 14 25° (NNE)

Meteors – The April Lyrids This shower is active from April 14th to 30th with maximum taking place on April 22nd at 17:00 BST. The best that can be expected in terms of activity is around 15 events per hour although a waning gibbous Moon in southern Ophiuchus will rise a little before midnight when the radiant is 35° in altitude. The Night Sky in April (Written for 22.00hrs BST mid month) In the east the spring constellations are beginning to come into their own with Boӧtes, Corona Borealis and Hercules now well above the horizon. Arcturus, in Boӧtes, is just past due east with an altitude of more than 35°. Hercules contains two of the finest globular clusters in the northern skies, the best being M13 at magnitude +5.8. This giant cluster contains at least two hundred thousand stars, which are far more tightly packed than those in our own Milky Way. It can be seen easily in binoculars or low power telescopes but instruments of 150mm diameter are needed to resolve the misty patch into individual stars. The other globular cluster is M92, which is slightly fainter and smaller and is often overlooked in favour of its brighter neighbour. Between Boӧtes and Hercules lies the small but perfectly formed semi-circle of stars that makes up Corona Borealis or the Northern Crown. By drawing a line through Arcturus and Alphekka (the brightest star in Corona) we can locate the faint shape of the “Keystone” which forms the lower body of the strong man, Hercules who, for some reason, is always drawn upside down. Turning to the south we find the celestial lion on the meridian as well as a waxing gibbous Moon (if you look at 22:00 on the 15th). Below Leo and slightly east (left) is the “Y” shaped group of stars that form Virgo with Spica, its brightest member, now nearly 20° in altitude. Slightly west of Leo is the hard to discern shape of Cancer (the crab) which contains the large open cluster M44 which is an excellent object to view in binoculars, as we found at our observing evening on Ashdown Forest. Cancer also has another

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open cluster (M67) a little to the south of M44. It is thought to be around 4 billion years old and have the mass of 1,300 to 1,400 solar masses. Just below Cancer is the head of Hydra, the water snake, whose body meanders south and east, finishing close to Spica in Virgo. Three small constellations “ride” on the back of the snake, Sextans (the sextant), Crater (the cup), and Corvus (the crow). Of these three Crater is the most obvious with its four brightest stars forming an irregular quadrilateral. As we look west we see that Orion is preparing to set for another year although some of his retinue are still moderately well placed. This is particularly true of Auriga and Gemini, the latter of which, containing the “Twins” of Castor and Pollux are still more than 50° in altitude. Capella in Auriga is 40° high which allows the collection of open clusters in the area to remain observable. These are Messier numbers 38, 37, 36 and 35 the last of which lies over the border in Gemini. In the north Cepheus lies close to the horizon and on the meridian with Cassiopeia to the west and the head of Draco to the east. The body of Draco takes a number of twists and turns as it winds between the two bears but the section closest to its head points directly to “Keystone” in Hercules that I mentioned earlier. Ursa Major is approaching the meridian above the pole with the zenith currently lying within its borders. The galaxies M81 and M82, positioned between the Great Bear and the pole, are superbly placed at an altitude of 70° and provide a good target for the imager with a DSLR and small telescope. Two of the three members of the Summer Triangle, Vega in Lyra and Deneb in Cygnus, are climbing away from the horizon. Fig 3 shows some of the clusters and galaxies mentioned above.

Brian Mills FRAS

OBSERVATION EVENING

We had recently been planning a star and constellation spotting evening and were lucky enough to get a clear sky and an acceptably mild evening on March 25th. We had a good turnout of members and were joined by visitors from Crowborough U3A Astronomy Group together with friends from a local exhibition who were keen to share the experience. There were a number of people equipped with binoculars and suitable telescopes together with two telescopes from the committee. Brian started the evening with a laser tour of the night sky showing how some of the constellations could be used to find other prominent and not so prominent groups and Messier objects. Orion was chosen as an example of this and Brian demonstrated how useful it was as a celestial signpost.

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He was able to show the difference between how the Orion Nebula looked to the naked eye and how it appeared in a 30 second exposure on a DSLR camera attached to a modestly sized refractor. The obvious differences were that there was a lot more detail and there was colour visible in the digital image. The combination of a suitably clear night and a good attendance made for a useful and pleasant experience, which we hope to repeat later in the year.

AN EVENING WITH THE ASTRONAUTS On the evening of Thursday the 21st of March four members and families attended a talk given by two NASA astronauts in the E M Forster Theatre at Tonbridge. It was a light hearted but informative evening with an audience of about 400 people. Michael Foale and Steve Swanson had been in space a combined number of 9 times. The evening was introduced by the Head of Tonbridge School who explained that the astronauts had been at the school for a week encouraging students in a bid to find a new experiment to be carried out on the International Space Station. Chris Barber of the ISSET International Space School Educational Trust then introduced the audience to British-American astrophysicist Michael Foale and Steve Swanson an American Space Engineer.

Michael Foale explained that his father had been a fighter pilot in the Royal Air Force and this is where Michael thought he would be following, but whilst at Cambridge University he began to pursue a career in the US Space Programme. He worked for NASA on the Space Shuttle navigation problems and went on to be selected to fly on the Shuttle to the Russian Space Station MIR. On the second visit to MIR, a supply vessel struck the station and it was Michael who was able to inform the Russians how to re-stabilise the station. He showed some of his experiments he had intended to entertain his family with using a couple of magnets he had smuggled aboard the International Space Station. He also entertained us with his experiments on how to deal with water, which came out of a straw as a floating sphere since there was no gravity. American born Steve Swanson was born in Syracuse and said he had expected his career to be in forestry, but at university he studied engineering physics and went on to be chosen as a systems engineer by NASA in 1987. He was selected as an astronaut in 1998 with his first flight as mission specialist and flight engineer in 2007. He flew into space three times.

Michael Foale, Steve Swanson and Chris Barber

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Steve showed several videos of life aboard the ISS which included how they kept fit, how difficult it was to eat and drink and how they relaxed, taking photographs through the observation dome of the station. He said it was quite odd to see 9 sunrises in twenty-four hours.

He also showed a number of casual experiments they had carried out with water, which included blowing bubbles into floating spheres of water and on one occasion encouraging a Russian astronaut to push his bald head into the water to see what would happen. One photograph they showed was of a lettuce grown without gravity. It looked pretty normal except that the leaves grew out at all sorts of angles. They said that when growing plants on the space station it was necessary to keep the soil inside a plastic container with just the plant stems poking through a hole, otherwise the soil would just float out into the surrounding air. When asked, Michael and Steve described lift off on the Shuttle as being violently thrust into space, but the landing was very gentle. This compared with the Soyuz with its gentle ascent but with a rather violent arrival back on land with a parachute to slow the capsule down before landing which was like backing your car into a solid object at 15 miles an hour! And then of course there is always the odd WAS member getting in on the act…

Michael Foale, Peter Rathbone and Steve Swanson

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2019 SUBSCRIPTIONS

From March 1st 2019 subscriptions will be £25 per adult and £35 for two members at the same address. Members under 17 years of age and students remain free. Subscriptions can be paid either by cheque made payable to Wadhurst Astronomical Society or as cash at the meetings or by post to: John Wayte Members Secretary Wadhurst Astronomical Society 27 Pellings Farm Close Crowborough East Sussex TN6 2BF The Subscriptions can also be paid via electronic banking to: Wadhurst Astronomical Society Account Number 35104139 Sort Code 60-22-15 Putting your name as the Reference so we know who is paying.

CONTACTS General email address to contact the Committee wadhurstastro@gmail.com Chairman - Brian Mills FRAS 01732 832691 Secretary - Phil Berry 01580 291312 Treasurer - John Lutkin Membership Secretary - John Wayte Newsletter Editor - Geoff Rathbone 01959 524727 Observing Director - Ian McCartney Librarian - Phil Berry Catering Manager - Jim Cooper SAGAS Representative - Eric Gibson Wadhurst Astronomical Society website: www.wadhurstastro.co.uk SAGAS website: www.sagasonline.org.uk Any material for inclusion in the May 2019 Newsletter should be with the Editor by April 28th 2019