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Christmas Meeting, 2008 December 13.

held at the Royal Astronomical Society, Burlington House, Piccadilly, London WI

Roger Pickard, President

Ron Johnson, Hazel Collett & Nick James, Secretaries

The President opened the third Ordinary Meeting of the 119th session and invited Hazel Collett, Meetings Secretary, to read the minutes of the previous meeting, which were approved by the audience and duly signed. The President said that 8 new members were proposed for election, and put to members the election of 15 new members proposed at the previous meeting; they were approved and declared duly elected.

The Papers Secretary, Nick James, was then asked to read the list of papers approved for publication in the Journal but on this occasion there were none. The President reminded the audience that the next Ordinary Meeting would be on 2009 January 28 at 5.30pm at Burlington House, and that there would be a 'Back to Basics' workshop in Canterbury on 2009 January 31.

The President then introduced the afternoon's first speaker, Guy Hurst, editor of The Astronomer magazine and head of the UK Nova/Supernova Patrol.

Studying exploding stars with robotic telescopes

Guy outlined the scope of his talk with his first slide as a backdrop; an artist's impression of the 1006 supernova, thought to be the brightest ever seen at magnitude -9. The speaker explained that his emphasis as far as supernovae and faint novae are concerned is now on CCD photometry, with visual observations reserved for brighter variables. He added that the talk would begin with a general statement of the aims of his own projects and then move into detailed discussion of the use of the Bradford Robotic Telescope for photometry, and the full range of objects that he is studying. Guy's own projects involve studying unusual eruptive objects including variable stars, quasars, novae, supernovae and the optical transients from gamma ray bursts, especially in the neglected late phases. Guy is also heavily involved with promoting amateur-professional collaboration, the rapid reporting of observations to professionals and the development of tutor-student mentoring schemes.

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The Bradford Robotic Telescope (BRT), a 0.35m Schmidt-Cassegrain telescope, is situated on Tenerife and comprises three CCD cameras freely available for public use over the internet. The Constellation camera is a 16mm F/2.8 lens covering a field of 40[degrees], the Cluster camera covers 3[degrees] and the Galaxy camera a field of 24 arcminutes. All three instruments have 1kx1k CCD detectors with filter wheels. A number of webcams are set up on site providing interactive views of the observatory and sky conditions including the sky at the pole and the town lights of Puerto and Teide. Results from the telescope are impressive with, for example, magnitude 19 achieved with 60 second unfiltered exposures. There is an easy to use interface with simple online forms to fill in and submit for observation requests. Once a job is completed an e-mail is automatically sent to the observer who can then download the images, which are typically 2Mb FITS files, for analysis.

The speaker then described the wide range of objects that he and others have observed with the BRT and other robotic telescopes. The characteristic of all the objects to be discussed was that they were not behaving as expected, which is why continuing to observe them was so important. One of the problems with doing photometry of very faint 'new' objects is the lack of suitable comparison stars, but it was possible to deduce reasonably accurate V-band magnitudes for photometry from star catalogues such as A2, and applying a suitable formula to red and blue values.

Quasars were the first group of objects discussed and the speaker noted that after the initial discovery many were rarely observed, but in some cases observation showed outbursts outside of their quoted magnitude range. An example is PKS1749+096 in Ophiuchus, which has a catalogued magnitude range of 16 to 18. An observation by Stefan Karge of Germany on 2007 April 25, however, showed it at magnitude 14.12, the brightest since its discovery in 1967, and there was also another outburst to magnitude 14.7 in 2008 July detected by the speaker.

Novae were discussed next with the speaker commenting that few were observed below about magnitude 14. Guy is interested in monitoring novae from maximum brightness right down to the quiescent magnitude, a decline that can take many years. Several old novae had been imaged at quiescence including CP Lac (found in 1936), DK Lac (1950) and DI Lac (1910) with some variation recorded near minimum.

The special case of V458 Vulpeculae was mentioned as being only the second nova known to have occurred in a planetary nebula, the other being (1901) GK Persei. V458 Vul was observed to have risen to magnitude 8.1 on 2007 August 8 from a magnitude 18 progenitor. As its magnitude declined to below 14 unexpected peaks started to appear in the light curve. It is estimated that the planetary nebula is about 14,000 years old with a high mass white dwarf at its centre, and some professional astronomers suggest that it might become a supernova in the far future.

The speaker moved on to discuss supernovae next and described the many different types with the aid of a diagram supplied by Tom Boles. All the currently active supernovae are listed on a web site run by David Bishop, which also has the discovery and follow up images of them. Different types of supernovae have different absolute magnitudes and rates of decline from maximum brightness. Mark Philips, a professional astronomer, suggested a link between maximum brightness and decline rate in a 1993 research paper and it is possible that activity on the lightcurve as it fades may be a factor, so they are well worth watching to the faintest possible magnitude.

Gamma ray bursts (GRBs) are also on Guy's target list and he pointed out that, although the popular astronomy press suggests that they are now understood, the professional papers say otherwise! It is generally accepted, however, that GRBs fall into two categories; those lasting less than 2 seconds which might be the result of the coalescence oftwo neutron stars, with those lasting longer than 2 seconds perhaps linked to extreme supernova events with the GRB coming some time before the optical burst. He showed a comprehensive light curve of GRB 030329, later classified as SN 2003dh, for which various observers contributed 91 measures.

Back on the subject of supernovae Guy mentioned his monitoring of SN 2007af in NGC 5584, for which the object declined 3.3 magnitudes in the first 100 days after maximum. The lightcurve covered 160 days during which it was seen to fade from mag 13 to 18, thanks largely to imaging with the BRT. Overall during 2007 Guy had secured 179 measures of supernovae and a further 108 results in 2008 up to the date of the talk.

The latest discovery from Tom Boles of supernova 2008eo in galaxy UGC442 was mentioned, this being Tom's 115th discovery. Also of interest was a discovery by Ron Arbour on 2008 December 11 of supernova 2008ex in UGC11428 at magnitude 16.5. Unknown to Ron at the time, this object had been previously discovered on 2008 August 17 by the Lick Observatory team at magnitude 17.1. The confusion arose from the different naming schemes used for these faint galaxies, the Lick team using a different catalogue designation for the same galaxy. What is very unusual about this object is that it is still bright after many months, so it doesn't follow the normal pattern of decline post maximum. This is yet another example of why follow-up observations post discovery are so important.

Guy concluded his talk by re-emphasising his main points: more quasars need monitoring to look for outbursts, novae close to quiescence sometimes vary in magnitude, supernovae decline rates do not always obey initial spectral interpretation and using robotic telescopes for photometry is not as difficult a task as some may think. Guy's final slide was of the Christmas Tree star cluster and nebula and was most appropriate for the time of year!

Following applause for Guy's talk the President thanked the speaker and invited questions. Roger Dymock asked about imaging moving objects with the BRT and commented that scheduling was an issue. Often there is such a delay in carrying out observing requests that the object of interest has moved out of the field of view before the image is taken. Hazel McGee asked about image trailing problems for photometry and focus control on the BRT. The speaker commented that the focusing was supposed to be automatic but that there were still some issues to be sorted out with it. Geoffrey Johnson asked about image saturation and photometry and Guy replied by saying that some trial and error was required to achieve the correct image density for accurate photometry. David Boyd made a comment that cataclysmic variables vary on time scales from minutes, in the case of 'CV flickering', to weeks; and finally the speaker was asked if old galaxy images could be used to subtract out the galaxy background to help with photometry of supernovae, and Guy commented that this may be possible but that more work was required to make this a practical tool. The questions and comments were followed by more applause for the speaker and the meeting was adjourned for a tea break in the RAS Library.

The winter sky

Following tea Nick James was invited to give the Sky Notes for December and January. Nick started by describing the visibility of the planets. Mercury and Venus were both evening objects but Mercury and Jupiter moved into conjunction during this period so would be unobservable for a time. Saturn remained well placed for observation and both Uranus and Neptune could still be seen after the end of evening twilight in the southwest. To illustrate the way astronomy was reported in the media, even by well respected organisations, Nick mentioned BBC news reports about the recent Full Moon which apparently was the brightest for years, and the coincident display of Geminid meteors at the same time!

The Sun was mentioned briefly with an image of a completely blank orange disk, but some rather nice images of the recent conjunction of the Moon, Mercury and Venus were shown to compensate, one by Denis Buczynski and the other by Nick himself from his office window. Nick also mentioned the lunar occultation of the Pleiades on 2009 January 7 with multiple graze events across the UK, and an annular solar eclipse visible from the Indian Ocean and Indonesia with a maximum duration of 7m 53s on 2009 January 26.

The current appearance of Saturn was explained with the aid of a diagram of the ring tilt with respect to the Sun and Earth and it was apparent that the next few months were the best time to see the very narrow ring system. Unfortunately ring plane crossing will occur during Saturn's conjunction with the Sun in 2009 September and will be unobservable. At this point Richard Miles commented that the next ring crossings would also be unfavourable, so the next time the rings would be seen this narrow would not be till 2039! Nick then showed some excellent images from a number of observers including Damian Peach's image of Saturn with Dione in transit and a storm in the STZ; a series of images from David Arditti through different filters, drawings by Bill Leatherbarrow and David Gray and a final image from John Sussenbach.

The currently observable comets were summarised next. Comet Lulin had been observed near the Sun in images from the SOHO spacecraft but the comet had been fainter than expected. Comets 2006W3 (Christensen) and 2006OF2 (Broughton) were both moderately good and comet 2008A1 (McNaught) was also observable. Comet 85P/Boethin had still not been recovered at this apparition despite accurate predictions of its position. Nick then showed some recent comet images including Mike Harlow's image of 2006OF2, Nick James' image of 2006W3 and the SOHO image of comet Lulin. Richard Miles continues to image comet 17/P Holmes with the Faulkes telescope although it has now faded to magnitude 20.

Special mention was made of Peter Birtwhistle who is currently approaching his 10,000th astrometric observation from the UK, which works out at almost 130 per month, since he started in 2002. This output is even better than the professionals can achieve at the Siding Spring Observatory in Australia.

Richard Miles, when not imaging comet Holmes, has been using the Faulkes Telescope South to measure the rotation rates of Near Earth Asteroids (NEOs). A recently measured NEO rotated in just 6 minutes and, given its estimated mass of one million tonnes, this suggests that it is a solid object and not a rubble pile which would be flung apart by such high rotation speeds.

After some final comments Nick handed over to Lorraine Crook who gave a short presentation on plans for the 2009 BAA Exhibition Meeting on June 27. Planning was at a very early stage but the venue had been fixed as the Royal Naval College in Greenwich. The venue offered excellent display areas for the exhibition as well as a range of nearby attractions suitable for a family day out. Further details would be announced as the planning progressed.

After applause and thanks there was time for a few questions. Dick Chambers asked how big asteroid Dodo was and Nick replied that it was approximately 30km across. Hazel McGee commented that the occultation would be difficult to observe due to the interference of strong moonlight. Finally Richard Miles was asked about using the Faulkes Telescope and gave some background information.

Following the Sky Notes the President introduced the next speaker, Mr Dale Holt.

The Reverend T. H. E. C. Espin (1858-1934), eccentric vicar and dedicated astronomer

Dale began by explaining how his interest in Espin had developed after his chance discovery of the observatory at Haileybury College in Hertfordshire where Espin had been a student. Dale's early research revealed that Espin had been a collector of telescopes, some of them quite large, which had mainly been gifts from his extensive network of friends and colleagues. Research also revealed that Espin was a rather eccentric character and this would be discussed later in the talk. To complete the introduction Dale gave Espin's full name: Thomas Henry Espinell Compton Espin, explaining that the Compton part was given by his godmother at the time of the christening.

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The story of Espin's life began with his schooling at Haileybury College. Espin did well in most subjects and at age 14 this is where his interest in astronomy started, stimulated and encouraged by Revd F. J. Hall at the school. At age 16 Espin was deeply influenced by the appearance of Coggia's comet in 1874April. Ironically the school astronomical society was formed after Espin left, but he did donate a telescope some time later. Today the school knows little about the observatory and claims the telescope was stolen, and few other details are known.

Espin's early astronomy was carried out with very simple equipment starting with opera glasses, progressing to a 1-inch Dolland refractor and then a 3-inch achromat made by Large. Despite his modest equipment Espin took every opportunity to observe and started to submit articles to the English Mechanic. Because of his young age Espin used the pseudonym T. E. E. He soon began to correspond with T. E. Webb (1807-1885) and this led to Webb asking Espin to collaborate on his book when Espin was aged just 17.

After studying in France for two years, Espin went to Exeter College, Oxford in 1878 to study theology. Also in this year he became a Fellow of the Royal Astronomical Society at age 19. While at Oxford, Revd C. Pritchard allowed Espin to use the 13-inch De La Rue refractor. After graduating with a 2nd class honours degree in 1881, Espin entered the priesthood and as was later said 'Started at the top and didn't need to work his way up'! Espin's first position was as curate in West Kirby on the Wirral in 1882 where he started serious work on photometry. In 1885 his father went to Wallsingham, Co. Durham and Espin soon followed.

At this point in his talk Dale entertained us all by describing Espin's many eccentricities which are amusing in a historical context but very far from socially acceptable by today's standards.

Espin considered himself a gentleman with a liking for fine food and wine and kept an extensive wine cellar. However, he despised the poor and was indeed known as the 'poor-hating vicar'. He loved guns and had a shooting range at the vicarage, but Dale was quick to point out that these last two facts were not related! He was a compulsive smoker of both pipes and small cigars and had vast quantities shipped up from London. On a more altruistic note he did pay for the steeple to be added to the church out of his own pocket.

Espin's interest in astronomy developed rapidly after leaving Oxford through his early years in the priesthood. He had started work on stellar photometry while still at West Kirby and during this time he helped to found the Liverpool Astronomical Society. He was presented with a 5-inch Tulley refractor by the shipping magnate J. Harrison and in 1885 he acquired the 17 1/4-inch Calver reflector that he used at Wallsingham. Espin was capable of great endurance when observing, sometimes for up to 13 hours, on long winter nights using a team of assistants taken from the local Boys Brigade to write down his observations so he could stay at the eyepiece.

In 1889 infighting in the Liverpool AS led to the formation of the BAA and Espin became Director of the Spectroscopic and Photometric Section. However he only stayed in the BAA for seven years, leaving after one of his books received a poor review in the Journal!

Espin made many discoveries as the result of his tireless observing. He discovered 4,118 red stars; following the work of Irish astronomer John Binugh, he discovered 50 Type IV or Secchi stars and 3,136 double stars. Indeed Espin is rated as the sixth most prolific observer of all time behind the likes of Herschel, Rossiter and Stern. Espin also discovered Nova 1910, DL Lacerta, and for this, and 40 years as an observer, the RAS awarded Espin a gold medal. Espin 'retired' from observing in 1932 but continued involvement up to his death in 1934. In 1973 a crater on the far side of the Moon was named for Espin and the speaker showed a picture of that crater imaged from a spacecraft. Espin's largest telescope was a 24-inch Calver reflector that he purchased in 1914 for his double star work. The telescope is still in use today on the original mounting at Newcastle University, having been rescued by David Sinden in 1961.

Espin was a great inventor, whose innovations included a variable power eye piece; a papier mache photometer; a stellar camera that he built in 1890; an illuminated micrometer for double star work that used optical fibres for illumination, an idea way ahead of its time; and a double prism spectrometer that could be used on stars down to 9th magnitude. One astonishing achievement was the building of an X-ray machine, just four years after its invention, which he used to X-ray the bones of some of his parishioners. Also on the medical side, he built a TB sanatorium in his back garden, although Dale's picture of this revealed it to be no bigger than a garden shed!

From 1912 onwards Espin had an assistant called William Milburn who was the son of one of his father's friends. While Espin was using his 24-inch Calver Milburn used the 17 1/4 inch reflector and Milburn continued observing after Espin's death into the 1950s. Espin also had a small menagerie of pets including newts and catfish, but his favourite was 'Kit' his cat.

And as if all these achievements weren't enough, Dale finished with a list of Espin's other interests including botany, microscopy, geology, music, composing and church organist. In summary, T. H. E. C. Espin was a dedicated and passionate astronomer who achieved a great deal over an observing career spanning 65 years. His output included many scientific papers published not only in the UK but also in journals in Canada, Germany and Brazil. In many ways Espin was ahead of his time with his use of large telescopes, innovations including the use of optical fibres and his experiments with X-rays; above all, he was a fascinating and eccentric figure in the history of astronomy.

Dale concluded his highly entertaining and informative talk by expressing his appreciation for the help of many friends and colleagues during his research into Espin's life. Two final slides showed Espin's gravestone at Tow-Law and the stained glass window in the church there.

The audience showed their appreciation for Dale's talk with prolonged applause and he was warmly thanked by the President. Unfortunately there wasn't time for questions so the meeting was adjourned until the Ordinary Meeting of 2009 January 28 at 5:30 pm, also at Burlington House.
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Title Annotation:Meetings
Author:Harlow, Mike
Publication:Journal of the British Astronomical Association
Date:Dec 1, 2009
Words:3559
Previous Article:Ordinary Meeting, 2008 November 22: held at the Royal Astronomical Society, Burlington House, Piccadilly, London W1.
Next Article:IC 1396 and the Elephant Trunk.

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