Cotswold C A Astronomical S Mercury Society

Volume 19 Issue 4 - November 2003

Alan Cahill’s new IN THIS BUMPER ISSUE Observatory Editor’s Spot 2 The Moore Observatory 2 Abbeydale Observatory 3 “Making” Astronomy 3 Sunspot Cycle #23 5 Asteroid 1937UB - Hermes 7 The Dumbbell Duo 8 A Question of Relativity 8 John Fletcher’s CAS talk 9 Rose Leicester Equatorial or Alt Azimuth? 11 and John Harris Mount Tuffley Open Day 12 receiving the Dan Coordinator’s Spot 12 Turton and Robin A Learner Joins 13 Townley awards DFYD 15 for 2003 Ian’s Word Search 17

Mercury - The Newsletter of the Cotswold Astronomical Society, founded 1982 Editor’s Spot sion with a “house sized” rock in September, we were by Peter Cadogan also revisited by that famous grazer of 1937 called Hermes, images of which were successfully captured Firstly, congratulations to Rose Leicester and John by both Alan Cahill and John Fletcher. Harris on winning this year’s Dan Turton and Robin Townley awards for their work in Africa and at Bredon school respectively. Following on from my request for more input to the newsletter, I am pleased to be able to include in this bumper issue a description of Alan Cahill’s new obser- vatory, the first installment of how Derek Maskell f irst became interested in astronomy and an article from Malcolm Mitchell on his solar radio observations. We also have news of John’s Moore telescope and an argu- ment against equatorial mounts from Jim Smith. My thanks to all contributors for making this such a packed issue. In future editions we also hope to hear about the observatories of John Rock and Mike Munden, as well as Graham Calvert’s quite remarkable observations of Mars, together with a regular feature from John Harris called “How do we know that?” The last two meetings went very well I thought - the Dear CAS “introduction to observing” session by Callum was I thought you may be interested to know that I have blessed with clear skies, so we were later able to now fully renovated to state of the art condition the observe Mars and other objects through instruments 12.5 inch F6 reflector that Sir Patrick gave me as a gift ranging from binoculars (including Jim Smith’s highly early this year. I have named it "The Moore 12.5 inch economical ones!) through my 3.25” brass refractor to reflector" in his honour. Also I have now completed Martin’s ETX with its speedy “goto” facility. the observatory which has a good view to the North Neil Bone’s talk on meteor observing was equally cap- East - South through to the South-South West for tivating and will hopefully inspire some of us to do observing the rising planets and the Moon to a point more of this form of “armchair” astronomy! My most just West of the central meridian. This will be a fine memorable experience was camping 10,000 feet up in compliment to my computerized automated robotic the Pyrenees on the day before England won the world work. cup in 1966 and beind enthralled by the display. But were these Delta Aquarids or Perseids? For those of It was made in 1950 and the optics were configured by you who, like me, missed John Fletcher’s recent talk, it Henry Wildey. As one knows, a Dobsonian sits on a is reproduced here. flat base and runs in Alt Azimuth mode. This one has So what else has been happening in astronomy and that flat base set at an angle of about 50 degrees and spaceflight recently? Well, there has of course been the the octagonal tube runs extremely smooth in both RA entry of China into the “Space Race” as well as the and Declination on ball bearings, hence in equatorial launch of Smart 1 on its slow journey to the moon. mode. I cannot wait to show you all the Moon and the Further afield, when Cassini passed behind the planet in Gemini through it. recently, on its way to Saturn, measurements of its radio signal provided yet more confirmation of Best wishes John. General Relativity Theory. More on relativity later in this issue. Other objects under the spotlight recently were near asteroids. Not only did we narrowly escape colli-

Page 2 New Observatory nelling matt black and coated the inside with a copper by Alan Cahill (Abbeydale Observatory) slip substance. The result is that now the roof slides perfectly for me.. one handed even! My thanks to Peter for the timely reminder about writ- After that I spent a week getting the electrics and con- ing something for Mercury. It has been a long time and trol cables out of the house, under the patio and into very lax on my part! the observatory. Lin and I did a great job with that. So what have I been up to in my search for asteroids? Doing most of the work during the evening, when the Quite a lot really. The first thing that happened was sun had disappeared behind the house. being given a Minor Planet Centre (MPC) Observatory Now the work is completed. All I need to do now is code. Many of you will remember my bungling of my slide the roof back, power up the scope, camera etc, possible discovery of an asteroid. Well hopefully all align the scope, and then disappear into my back room that is now in the past. Now when I do my observing in the house and control the whole setup from there. of asteroids, the data is sent to the MPC and used. The After years of being out in the cold, this is luxury! second thing I have done is build a purpose built That is a cut down version of how the observatory was observatory. This really was a must. built. What it doesn’t tell you is all the hard work put in by mine and Vaughan’s families. I’m sure he will In the past I have had to manually carry out my tele- tell you that it was fun. And it was! I was astounded. scopes on to the patio, plus assorted leads.. and now All the plans for this were in my head but at the end of having a 8 inch scope, it really was getting beyond me. the day I couldn’t be certain that it would work in Most of you know about my disabilities so I’m sure practice. With Vaughan’s mechanical skills we got you understand the situation. Thank God I have an there and I’m really proud and grateful. understanding wife!! Her help in the past has been essential. On the front cover of this issue is a photo of the fin- Anyway, with much prompting and encouragement ished product. So I hope it now makes sense. If anyone from members of the Society (in particular John wants to know more about building one feel free to Fletcher and John Rock) the observatory is now a reali- speak to me. ty. A special thanks goes to Vaughan Willoughby and family. They pitched in for a full weekend, under a "Making" Astronomy scorching sun, and completed the building with me. I by Derek Maskell still have this picture in my mind of Vaughan lifting the roof off the observatory on his own! Astronomy nowadays is there for all for those who care to take an interest, it always was, perhaps, but in The observatory is a converted 7ft square shed. What I this day and age there are so many magazines and out- did was, buy a conventional shed and adapt it into an lets advertising all the high-tech equipment necessary observatory. How you may ask?. Well here goes. to become involved. Times weren’t always like this. Equipment, and most importantly, money was not as The idea was that the observatory would have a slid- readily available as it is today. Most telescopes fifty ing roof so that the scope has a virtually unimpeded and more years ago were home-made and, although view in most directions. This worked well and now I the ancillary equipment may not have been technically have good views from East through South to West. advanced, first class mirrors were within everyone’s Perfect for asteroids! grasp and were made by enthusiasts with no particular The first thing I had to do was lower the shed. After all technical skills at all, mostly resulting in a fine sense of it was around 7ft high and there wasn’t a way in hell achievement. I have been asked many times why I use that I could see over the sides.. let alone the scope! This a home-made telescope and how it came to be, this is was accomplished by cutting just over 1 ft off all four the story. sides. My idea was to cut it off the top of each side (not being very DIY savvy!). Lin my wife soon showed me As a young boy I held an interest in astronomy. Way the error of my ways, by cutting it off the bottom in back in the 30’s light pollution was unheard of, the stead! That way windows didn’t need cutting down as miserable gas lamps in the streets where I grew up in well! NW London, gave a dim white glow, very little down- That accomplished I now got a firm in to lay an 8 ft wards and almost none upwards due to the design of square concrete base. I have to say I had my doubts the lamp housing. The lamplighter used to do his about how level they would get it. But I needn’t have rounds on a bicycle carrying a 10ft ladder to enable worried, they really did a great job for me. him to wind up the timing clocks and relight those The next part was figuring out how to get such a large pilot lights which had blown out. Such was the extent roof to slide off the observatory. I solved that by pur- of the light back then, it did nothing to mar our view chasing two 14ft lengths of U shaped alloy to act as the of the heavens, brilliant black skies, never likely to base for the roof to slide in. Next I purchased 10 return to suburbia. wheels for attaching to the roof. These wheels in turn From 1939 to 1945 the lamp posts were unlit, no lights slotted into the U shaped channelling that was allowed to leak from windows. And the few vehicles attached to the top of both sides. I painted the chan- that were on the road had their headlamps masked Page 3 with nothing more than a few thin slots to bleed some entitled ‘Amateur Telescope Making’ (ATM) in three light out. Eyes were always turned to the sky at night, volumes, edited by Albert Ingalls. They comprised a excited by seeing the bombers caught in searchlights. collection of jottings about the art of making mirrors Then, when all was clear and they had done their and telescopes as originally published in a magazine deeds and returned home the sky would just shine called Scientific American in the 30’s and 40’s. The set with stars. In those days I knew telescopes existed, to has been reprinted/updated and is available today. A my young mind they were long thin things made of quick browse through and I was hooked, it all seemed brass mounted on tripods, totally beyond my means very possible that I could soon actually have a tele- or of anyone that I knew. I had read also that were scope. No 1.5 inch (38mm) object lens with those some really big ones in other lands atop mountains. annoying coloured edges for me, this was going to be Even the great 200 inch Palomar telescope had yet to big time, a ‘huge’ reflector was my aim, 6 inches in be completed at that time. diameter (150mm) no less! Sounds puny now but a fine instrument for those days. Towards the end of the war, stores were selling ex-War Department (WD) items, bombsights, gunsight, sur- Glass, I read, preferably low expansion Pyrex, was the veying equipment, all sorts of optical gadgets, not sur- material to use for a mirror, no possibility of my prising that amongst these items were thousands of obtaining anything like that and to my way of thinking lenses which always attracted my attention, I bought any glass was better than nothing so I located two some for a few pennies. pieces of what was called ‘pavement’ glass, one for the mirror and one for the tool, both 6 inches square and I visited one such shop in East London called almost 1 inch (25mm) thick. I later discovered that Broadhurst Clarkson & Co. Ltd., in Farringdon Road pavement glass was usually well annealed with stress- EC1., established in 1893. The shop, on that site since es relieved, making it well suited for making telescope 1908, was very lucky to escape destruction. My memo- mirrors. With glass cutter and much hard work I ry of that visit back in 1942/3 was that the area was chipped away at the corners to make them almost cir- one of just about total devastation. The shop stood cular and then finished off the edges by grinding with almost alone amid flattened buildings as a result of the carborundum powder and lots of elbow grease. blitz. Brass telescopes and lenses were made on the Eventually, I started grinding one disk surface against premises but my main memory is that the showroom the other, to produce a concave surface on the upper was stacked with the ex-WD equipment. Now, of (the mirror) and a convex surface on the lower (the course, we all know it as a major stockist trading under tool), meticulously following the advice from the name of BC&F books. Reducing the grit size I had soon (??) produced Along with some friends we would determine the focal a curve in the mirror which reflected a light at just over length of a lens by bringing the sun’s image to a small 48 inches (1.2m) focal length i.e. at 6 inches diameter, point on the back of the hand (that hurt!), fix the larg- F/8. Then, changing the glass tool for one of pitch and er convex ones to the end of a tube of rolled-up paper rouge, started polishing. Meanwhile I fabricated a and the smaller plano-convex ones at the other end, Foucault knife-edge tester in order that the shadows point it to the sky, adjust the spacing and wonder at reflected by the mirror could be interpreted accurately. the view. Thus did I catch my first glimpse of The object being to polish the mirror to a spherical and its four major moons. Never mind the pretty shape, then slightly deepen the centre to obtain a para- colours at the edges, blue on one side and red on the bolic curve. Needless to say that mirror making and other, we had made a telescope! testing is an art in itself and I could probably fill a From a very young age I was fascinated in all things book on the subject, as many have. Basically, if a tele- electrical. It surprises me even now that I pursued an scope mirror is to be useful it has to focus all incoming apprenticeship as an engineer mechanic, a skill which parallel light across its surface to a precise point, so has, I’m pleased to say, been invaluable to me ever has to be worked (figured) to a tolerance of only a few since. During this training, which, in those days lasted millionths of an inch. This sounds impossible for the for about five years, I discovered that anyone who had average person to achieve but in fact with patience, not the inclination, a bit of skill, and a good deal of difficult, it is far easier work a curve to that accuracy patience could actually make a serious telescope with than it is to work a flat surface! a reflecting mirror. I do not recall that any astronomy The Foucault tester, (named after the Dutch scientist magazines were available in those days, no instant who invented it), comprises no more than a diverging astro-information, nor any affordable telescopes for light source and a knife edge to cut the reflected light sale, besides, with wages in the order of £2 -3 per rays. Using these simple tools, minute changes in the week living expenses took priority over such things as shape of the mirror’s surface can be seen and interpret- telescopes. ed very easily. My efforts took me 3 months of So it was that one day in the early fifties, soon after I evenings before I was satisfied that I had produced as had completed National Service in the RAF as an perfect a mirror as I knew how. instrument fitter, a colleague heard that I had an inter- The next part of the process was to give the worked est in astronomy and pointed me in the direction of the surface a reflective coating. The book said a surface local library, along with a note about a set of books coating of silver had the highest reflective index but it Page 4 quickly deteriorated and oxidised, it also involved consult, in fact no one particularly interested in what I playing with nasty sounding chemicals, aluminising was doing. It was not one of those brass tube things was the new technique which although having slightly on legs, it was different, it was mine. I knew that the less reflectivity lasted longer. It consisted of depositing mirror was correct according to the information taken a very thin film if aluminium to the curved surface of from Mr Ingalls tomes. I also knew that it was a great the mirror which, in itself is quite an involved opera- advantage to able to move the telescope in opposition tion and has to be carried out in conditions of high to the motion of the earth so that I could observe for a vacuum. duration longer than a minute or so, I had to put some thought into mounting it properly. At that time, early fifties, I was working at the GEC Research Laboratories, and I was able to obtain the use ..... to be continued of some high vacuum pumping gear so, after studying the processes involved, aluminised the mirror myself. Sunspot Cycle number 23. At the first attempt the aluminium was too thick and by Malcolm Mitchell the coating crystallised but, after cleaning it off with nitric acid, the second attempt was fine and, in fact, For the past 15 years or so I have played at amateur even without the modern protective coatings used radio (call sign G0LVB, shades of Hancock etc !) and I today, lasted for 40 years. I had it re-aluminised by the have been monitoring the changing solar cycle for the David Hinds company in 1992. last few years by plotting the daily readings of the sunspot count and also the 10cm solar flux. Having finished the mirror I recall the elation I felt at that time. I had transformed a simple piece of glass Sunspot observations have been made for hundreds of into a holder for an aluminium reflective surface years and form a valuable historical record of the sun’s merely 200 angstroms thick capable of revealing the activity. However, as sunspots do not come in a stan- most wonderful views of the heavens. How to use it dard form, they not a precise measure of solar activity. was now the problem I had to face. Solar flux measurements (the energy emitted within a certain waveband) on the other hand are a quantitative From a WD surplus stores I found a 1 inch right-angle measure of the sun’s output at a particular wavelength. prism, now known as a star diagonal, this was to act as Most people are familiar with the notion of the 11-year the secondary mirror. Then, by carefully matching sunspot cycle (perhaps better described as a 22-year two small plano-convex lenses I made up a simple cycle with alternating polarity). What is normally Huygenian eyepiece of 1 inch equivalent focal length. shown is a plot of sunspot counts based on monthly All information as to the size and spacing of these lens- means which have been smoothed further by taking a es was gleaned from the ATM books. A focus mount 12-month running average. However, the averaging, or was fabricated from an old microscope part having a smoothing, process removes some interesting details. rack and pinion. All the parts were then mounted on a Comparing the daily sunspot and solar flux measure- short plank of wood with the mirror very carefully ments clearly shows that the two are related and that fixed to a shelf at the lower end. There I was, the they both vary significantly on a daily basis – further- proud owner of a Newtonian telescope. more they both show the effect of the sun’s rotation.

As with all such occasions, the advent of having a new Sunspot numbers have been recorded by the Zurich telescope to hand prompts the arrival of wind, rain, Solar Observatory a regular basis since 1749 and daily cloud etc, so it was some days before my new posses- sunspot numbers have been reported since 1849. In an sion was proudly, and very carefully, carried out into attempt to standardise the reporting by various obser- the garden. There, I propped the contraption up vatories around the world, in 1852 Rudolf Wolf, the against a lawn mower (no kidding) and aimed it Zurich Observatory director, came up with the follow- towards the 7 day old moon, that in itself was not an ing formula for the sunspot number: easy alignment process. How can you ever describe the feeling of your first R = k( 10g + f) views of the moon particularly after so much time and effort? This thing I had created was amazing! Where: Mountains, ridges, craters, bright bits, dark bits all R is the Wolf relative sunspot number were revealed in the brief minute or so before it drift- ed from my vision and light from stars then filled the f is the total number of sunspots either individually or view. Not pinpoints exactly, the collimation was any- in groups thing but precise. g is the observed number of sunspot groups (the factor This was the first time I had ever looked through a 10 was chosen arbitrarily to give greater weight to ‘proper’ telescope. That’s if ‘proper’ can describe what large, active groups). I had made. I had no friends or colleagues with experi- ence or knowledge of such an instrument, no one to k is a different factor for each observatory - dependent Page 5 10 cm Solar Flux and Sunspot Numbers

600

500 Sunspot number Solar Flux

400

300

200

100

0 Jan- Mar- May- Jul- Sep- Nov- Jan- Mar- May- Jul- Sep- Nov- Jan- Mar- May- Jul- Sep- 01 01 01 01 01 01 02 02 02 02 02 02 03 03 03 03 03 on the telescope used and the general conditions best time to try to establish a radio contact with a fel- (astronomers eyesight etc). low ham in New Zealand for example. The variations in the electron density are caused largely by the ionis- The standard sunspot number is therefore, perhaps ing effect of UV solar radiation in the ionosphere some surprisingly, not an approximation of the number of 50km to 300 km above the earth’s surface. Although sunspots: rather it is a sort of index of solar activity. the biggest differences in radiation occur between Wolf later converted those data going back to 1749 to night and day and due to the seasons, there is a sec- sunspot numbers on the same basis. The result is that ondary effect associated with the sunspot cycle and it we have a continuous record of sunspot activity over has long been recognised that there is a positive corre- the last 250 years – plus some less well calibrated earli- lation between the UV solar radiation and sunspot er numbers. Cycles are numbered from trough to activity. It is well known among radio hams that long- trough starting with cycle 1 in 1755 and we are cur- distance communication in some frequency bands (e.g. rently just past the peak of cycle 23. 10 meters) is very difficult during the solar minima. My very limited experience is that amateur prediction Since 1981, the responsibility for computing the so- programs don’t work too well, but it is fun to try! The called Zurich sunspot number was transferred from military spend a fortune on this sort of thing using var- the Swiss Federal Observatory to the Royal ious sophisticated data-gathering techniques and much Observatory in Brussels (this was a non-political move fancier programs - however the physics is pretty com- effected long before the EEC tried to rule us all from plicated and I wonder if they do much better ! Brussels). The centre has an excellent web site, well worth a visit - enter http:// sidc.oma.be (SIDC The 10.7cm flux data (corresponding to a frequency of stands for Solar Influences Data Centre). There is a 2800 MHz) are recorded by Dominion Radio wealth of information on this site; apart from statistics Astrophysical Laboratory, Penticton, BC, Canada (for on sunspots, solar flux, x-rays, space weather forecasts some reason, the Canadians play a prominent role in etc there are super images from SOHO - the space tel- this area and have been monitoring since 1947). The escope pointing at the sun. data are available on the internet, e.g. the SIDC site. For morse code buffs, they are also reported daily by a The solar flux data are of interest to radio amateurs, German radio beacon (DK0WCY) on a five-minute among others, because they can used in radio propaga- cycle transmitted on 10.144 MHz. tion prediction programmes as a guide to the likely electron density in the ionosphere. Radio hams like this The daily figures for solar flux and the sunspot data sort of stuff so that they can work out when will be the have been plotted together for comparison. The Solar

Page 6 Flux Unit data plotted in the chart have all been increased by 200 simply to separate them from the sunspot data which they would otherwise overlie. It can be seen that the two curves are similar but that the sunspot plot is more "jittery". Although there are fre- quent large daily variations, particularly in sunspot number, the predominant period is close to that of the solar rotation (about 27 days); furthermore, the plots are in phase (or in step) with each other. Analysis of these data over the period from August 1999 to Sept 2003 shows (very approximately) that

Solar Flux = 0.5 x Sunspot Number +90

This suggests that the flux does not drop to zero even Early on October 15th, Brian A. Skiff (Lowell Observatory if there are no sunspots visible. Near-Earth Object Search, Arizona) sent measurements of four CCD images obtained with the 23-inch Catalina The smoothed sunspot plot, taken from the SIDC web- Schmidt telescope to the Minor Planet Center in site, are shown in the second plot which includes data Cambridge, Massachusetts. At the center, Timothy B. to mid 2002 – the last point available. This plot sug- Spahr identified the suspect with other measurements sub- gests that the peak of cycle 23 occurred in the first half mitted in the past seven weeks -- but not recognized as of 2000 and that the minimum should occur around unusual – by LONEOS and by the Lincoln Near Earth 2006/7. The plot also shows that although the perio- Asteroid Research (LINEAR) project in New Mexico. In dicity of the curve is reasonably regular, the ampli- addition, quick action by James Young (Table Mountain tude varies enormously: 1957 must have been an inter- Observatory, California) secured a confirmation just before esting year for solar astronomers (and probably pro- dawn on the 15th. duced some interesting radio propagation too). The relation between sunspot numbers and solar radiation Hermes is by no means the last of the "lost asteroids" -- in the visible and infra-red is thankfully pretty weak if many thousands of others in the Minor Planet Center's not practically non-existent ! Nevertheless, some past database fall in this category because they could not be fol- minima, for which observations are scanty, have been lowed long enough for an accurate orbit to be determined. linked with unusual cold periods in the Middle Ages. But Hermes is by far the most famous. It was discovered by Karl Reinmuth at Heidelberg, Germany, on October 28, What are the implications for us if cycle 23 is past its 1937, and tracked for only five days. Although never offi- maximum ? Well, on average, the 10cm and UV radi- cially numbered, it has been known by the name Hermes ation levels will decrease. For those earthbound ever since. (picture below courtesy of John Fletcher) astronomers and others who venture out to sunbathe there will perhaps be a slightly reduced risk of skin cancer. For astronauts or International Space Station occupants (and space tourists ?) there will be a reduced risk of being bombarded by particles from solar flares and coronal mass ejections; similarly, the need for special shielding (radiation hardening) of electronic components in satellites will be reduced at least until cycle 24 is well underway. Of course, we can never be sure of the future: there is no quantita- tive explanation for the timing of the solar cycle, moreover there is some evidence that in the distant past (pre 1700’s ) the solar cycle was less regular than it appears to be at present. Perhaps it is a bit early to call the peak of cycle 23; anyone like to place a bet on the date of the next minimum ?

Asteroid 1937 UB (Hermes) Recovered. Near Earth Asteroid Warnings by Alan Cahill by John Fletcher

Below is an image of Hermes I managed to take on the The following letter was sent by John to a number of 16th October, 2003. Just 1 day after the asteroid was local newspapers. . . ‘recovered’. Below is a small quote on the history and recovery of Hermes. I thought you might interested in For the Editor in charge. With reference to the recent Earth impact Asteroid Page 7 scare, the Lincoln Near Earth Asteroid Research two bright structures and so was designated NGC 650 Program (called LINEAR ) discovered Asteroid 2003 and 651. Later observations showed the two to be one QQ47 on the 24th Aug 2003. . nebula, and it was given the designation M76 along This warning went out to the media and made with the common name of The Little Dumbbell as it National Headlines immediately. More recent obser- had the typical dumbbell appearance. vations allowed astronomers to conclude there was no M76 is somewhat more difficult to find than M27 as chance whatsoever for impact with our planet in 2014. its size is only 1.6 x 1 arc minutes with a total light The first false alarm was in 1998 when an astronomer equivalent to a star of magnitude 12 making it the went public with data and stated that an asteroid dimmest object on the Messier list. Its position is, RA named 1997 XF11 had a chance of hitting Earth inthe 1hr 42.3min, 51deg 34.25min north. year 2028. Once again the asteroid was rendered harmless by more backup observations. Both images shown were taken recently from my Pictures of the first false alarm of the asteroid 1997 rather light polluted garden site in Gloucester with the XF11 as it passes close to the Earth over F/5 10" Newtonian and MX-7C CCD camera, single Gloucestershire at the link below. You may use the exposures each of 30 seconds. If you download the images which are in black and white format if you are ‘Mercury’ from our web site you have the advantage interested. of seeing them in colour.

A Question of Relativity TWO TO FIND - the Dumbbell Duo The following is an extract of a letter sent to me by a by Derek Maskell Dennis Spratley of Leicestershire.

M27 (NGC 6853) is commonly known as the In the May 2003 issue of Astronomy Now the follow- Dumbbell Nebula, a fine sight with a size of 8 x 4 ing question was asked: "Why is the relative velocity minutes of arc, it has an apparent magnitude equal to of two galaxies at the edge of the observable universe, a star of about 8 it is easily seen with binoculars or a each travelling away from the Earth in opposite direc- telescope. At a distance of 1,250 lightyears it is to be tions at close to the speed of light, not almost twice found in the constellation of Valpecula just 23 arc light speed?" minutes south of the 5th magnitude star SAO 88016 It is only necessary to give the first part of the opening (14 Valpeculae). If your telescope has no goto facility sentence of the reply as follows. (or even just for good practice) follow Callum’s pro- "It is because of the special theory of relativity (SR), cedures on star hopping which Einstein published in 1905. . . " At its centre lies a 13.5 magnitude star whose radia- This is quite wrong. The SR does not apply over cos- tion causes the rarefied gas to fluoresce and glow mological distances. In fact the SR may be described quite greenish when seen in transparent skies. A mag- as physics in the absence of gravity. Since the universe nificent large nebula viewed against the background is dominated by gravity the solution to the problem of the of the Milky Way at RA 19hr 59.6min, 22deg requires the general theory of relativity (GR). This was 43.3min north. published in 1916 by Einstein and is the definitive the- ory of gravity of our time. On the other hand the SR is Some 70 degrees across the sky to the west in the con- a restricted theory applying only to 'local' regions of stellation of Perseus we find its rather diminutive space-time. namesake, M76 at 3,400 light years, it is just over twice It is, of course, incumbent on me to give the correct the distance of M27. In early sightings it was seen as answer. This is where the trouble begins! For years I

Page 8 have struggled to get across to some, but not all, Talk given to the Cotswold AS astronomy society members the nature of the expan- by John Fletcher. sion of the universe. Firstly, objects in recession are not moving through space as would be the case result- Astronomical Imaging. ing from an explosion; they are moving with the Astrophotography expansion of space itself - in simple, interpretive CCD Imaging terms the 'stretching' of space. Secondly, as stated, the Deep sky Objects SR theory does not apply. If we take the simplest case Near Earth Asteroids. the space is 'flat', or Euclidian, or if you like, is as in Astrometry and Photometry. school geometry, which is the current view of the cos- mologists, then cosmological velocities add together in First I showed how a standard 50mm lens can record the simple way that we learned at school. So if we 1000 square degrees of sky in a 24 second exposure consider the two galaxies, say A and B, in opposite using fast colour, or B & W film of 400 asa or faster. directions in the sky, both with a recessional speed rel- I then moved onto telephoto lenses which piggyback ative to us of just under the speed of light, we may ask mount on a driven equatorially mounted telescope for the question: what is the speed of A relative to B? longer time exposures. Stationary anything longer The answer, contrary to the assertion in the 'AN' read- than 4 seconds with such a lens when mounted on a er's question is, in fact, just under twice the speed of stationary tripod would record trailed images due to light! This is why, in principle, we on Earth can detect the rotation. A and B but it is not possible for A and B to 'see' each A picture of Polaris, in Ursa Minor was shown taken other. with a 300mm lens at F5.6 and a five minutes expo- I do not expect to be believed by all readers of my let- sure. It was an unguided Piggyback mounted unguid- ter. Consequently before any possible overreaction let ed. Observed with binoculars one may see a little cir- me recommend that those who would instantly reject clet of 7th and 8th magnitude stars just south of the what I have written first consult the brief list of rec- star. This is called the "engagement ring" of Polaris. ommended reading. Polaris being the bright celestial solitaire.

Understanding Relativity by Leo Sartori, I then moved to prime focus astrophotography and University of California Press showed many of my earlier photographs including Essential Relativity by Wolfgang Rindlar, Messier 81 and 82 in Ursa Major. I spoke of and Springer-Verlag explained many of the drawbacks with a telescope Basic Relativity by Richard A. Mould, Springer that is not computerised and has to be perfectly polar ------aligned and the need for manual guiding to obtain Editor’s thoughts . . . . perfect stellar images.

I think that Dennis must be correct here, but would I then spoke of the fully computerised telescope that I like to make a few points of my own. Firstly, these use in conjunction with a modern CCD camera. I distant galaxies must be very distant indeed for their spoke of the setting up of equipment. I showed many recession velocities to be an appreciable fraction of deep shots of objects such as Messier 106. Bright light speed (say 0.7c) and we are therefore seeing Galaxy in Canes Venatici. Messier 27 "The Dumb-bell them as they were about 10 billion years ago. nebula". Nov Cygni No2. Binocular object when at maximum. A recently discovered nova. NGC 891 an When we discuss the relative velocity of one as Edge on galaxy in Andromeda. The planet . I viewed from the other, we have to ask ourselves showed the motion of the planet. See my chapter in whether we are in the current epoch (ie 15 billion 2003 yearbook of Astronomy on Pluto. years after the Big Bang) or do we mean as we are Also the raw image and processed images already seing them today (ie only 5 billion years after the Big seen in Mercury of the Afterglow of gamma ray Bang)? If in the current epoch, then our own Galaxy Burster. would presumably appear as it was 5 billion years GRB 030329.2003y 03m 31d. 20-24-29UT mid exposure. after the Big Bang and receding at 0.7c. Asteroids Directly behind us should be the other galaxy, but it cannot possibly be 20 billion light years away and I then spoke extensively about the work an amateur receding at 1.4c can it? Does it exist yet? As I under- can do in astrometry. Astrometry is the accurate meas- stand the current inflation models, as time goes by urement of the exact positions a celestial object. In my more and more of the inflated universe comes into case of the ever-moving minor planets. This is serious view - what we see today is still but a tiny faction of Pro-am collaboration and is of extreme importance the “whole”. This is mind boggling indeed. . . . especially when monitoring the positions of Near Members may like to make their own comments about this Earth Asteroids (NEA's) There are three types of issue in a future issue of Mercury . . . asteroids to keep an eye on. They are the below.

Page 9 Each data line below this info is for a single image Near Earth Asteroids Amor – Apollo - Aten taken. Take the first line on left. 1. J97A12E is the asteroid name/number. There are also the Potentially Hazardous Asteroids. 2. Next is year month day. C2003 09 06.xxxxxx (PHA's) These are generally larger than 100m and 3. After the dec. point is the time of day in fractions. come closer to the Earth than 0.05 AU. AU = astro- 4. After that moving right comes the positions in RA nomical unit. Sun Earth distance. and Declination. Note the changing positions on below measurements with a ASTROMETRICA maximum of 120 seconds between images. Astrometry software by Herbert Raab. Austria 5. Then comes the magnitude in "v" "V" magnitudes To do the astrometric measurements of the asteroid are recorded without the use of U.B.V and R profes- positions one has to take three images with a time gap sional filters. between each. This will show the objects motion 6. Finally the observatory code. J93 for Mount Tuffley. against the background stars. The three positions are COD J93 then measured using software. An orbit arc can then MEA John Fletcher be determined. In my case I use the above software NET USNO-A2.0 called Astrometrica. It is not so simple until every- TEL 0.254m f/5.5 Schmidt Cassegrain + CCD thing is in place. First you need a huge database with ACK MPCReport file updated 2003.09.06 23:40:46 millions of reference stars, omitting the variable stars. AC2 [email protected] I have the full U.S.N.O. "U S Naval Observatory" datasets on a second hard disc on my PC. This shows J97A12E C2003 09 06.85245 02 10 06.23 +43 45 22.6 16.3 V J93 all the data on stars to 24th magnitude. J97A12E C2003 09 06.85457 02 10 07.69 +43 45 30.3 16.6 V J93 J97A12E C2003 09 06.85669 02 10 08.84 +43 45 37.6 16.2 V J93 Also you need to regularly download and update the K02C10E C2003 09 06.83390 22 34 58.98 +13 59 09.5 15.2 V J93 Minor Planet Orbit data from the Minor planet centre. K02C10E C2003 09 06.83582 22 34 58.32 +13 59 02.8 15.0 V J93 The Mpcorb.data unzipped is about 30MB. K02C10E C2003 09 06.83794 22 34 57.82 +13 58 56.4 15.4 v J93 Astrometrica finds the positional data from a few hun- K03K02P C2003 09 06.91618 15 29 34.03 +58 37 12.1 16.8 V J93 K03K02P C2003 09 06.91829 15 29 33.62 +58 37 08.0 16.8 V J93 dred or less reference stars around the asteroids posi- K03K02P C2003 09 06.92041 15 29 33.32 +58 37 05.9 16.9 V J93 tion and compares the positions of the minor planet K03K02P C2003 09 06.92464 15 29 32.59 +58 36 59.1 16.9 V J93 on your three images. The RA and Dec positions K03Q30Z C2003 09 06.89382 21 50 43.34 -01 53 52.4 16.7 V J93 down to fractions of a second of arc are then saved for K03Q30Z C2003 09 06.89794 21 50 43.06 -01 53 57.4 16.4 V J93 K03Q30Z C2003 09 06.90433 21 50 42.39 -01 54 06.3 16.3 V J93 your three images of the object. There is a lot more to K03Q30Z C2003 09 06.90645 21 50 42.10 -01 54 09.5 16.3 V J93 it than this as spoken about in the talk. 02100 C2003 09 06.81983 19 58 24.00 +00 26 06.8 14.5 V J93 Basically an automatic official MPC report is created 02100 C2003 09 06.82125 19 58 23.94 +00 26 00.0 14.5 V J93 which has all the data on it as seen below on the 02100 C2003 09 06.82267 19 58 23.85 +00 25 52.6 14.3 V J93 07336 C2003 09 06.87354 22 49 07.22 +01 25 28.9 16.2 V J93 recent observing run I did. 07336 C2003 09 06.87566 22 49 07.54 +01 25 26.4 16.4 V J93 07336 C2003 09 06.87778 22 49 07.92 +01 25 22.8 16.3 V J93 On the offset, if your astrometric work has been 24445 C2003 09 06.94345 20 10 08.62 +24 27 26.5 16.6 V J93 accepted then you are given an official observatory 24445 C2003 09 06.94557 20 10 08.44 +24 27 24.0 16.4 V J93 24445 C2003 09 06.94769 20 10 08.35 +24 27 21.5 16.5 V J93 MPC code. Mine is Code J93. All the amateur 25529 C2003 09 06.95990 00 26 17.74 -00 44 23.0 16.9 V J93 astrometrists who are submitting measurements and 25529 C2003 09 06.96201 00 26 17.66 -00 44 23.0 16.8 V J93 their work has been accepted and given a code are 25529 C2003 09 06.97128 00 26 17.25 -00 44 23.1 16.7 V J93 listed alongside professional observatories such as 250 Hubble, 00.00 Greenwich and all the others around the Two examples of close objects that I recorded in the World. In other words you can earn International past but not Earth threatening are listed below. recognition. There are two other observers in the CAS 2002 NY40 "Potentially Hazardous Asteroid". who have official observatory codes. John Rock and 2002 NY40. Apollo. Diameter 910metres. Alan Cahill. They are both submitting there measure- Distance from home planet 16/08/2002 0.001 AU ments to the MPC at Harvard University, CA like myself. P.H.A. 1978 CA. Apollo 02/03/2003 Distance from home planet 0.01 AU. Diameter 2.5km Below is an official MPC report created throughout an observing run on 2003.09.06th recently at MTO UK. Internet users. It gives my observatory = J93 Look at the Observatory codes at. The measurer = MEA Just type into the search box < List of observatory Data set for reference stars = U.S.N.O. codes >. The actual address is huge so this is easier Instrumentation = Scope/CCD until you save it to your favourites. Report file final update prior to submitting. For downloading data go to. Time/date. < http://cfa- Return confirmation for acceptance or contact. www.harvard.edu/iau/Ephemerides/Soft02.html > For asteroid Unusual listings/Critical Listings/Distant

Page 10 listings. Plus visible comets (many when fainter at teur astronomer ? To make full use of an equatorial 12th and 14th magnitude). head it should be permanently sited otherwise contin- The big one. ually having to set it up every time is a pain. And how http://www.astro.cz/mpcorb/ much use is made of the setting scales? If you are Simply download the mpcorb.zip (10MB) and unzip very keen then they are useful for obtaining the coor- to disk. dinates of an unknown object or for setting the coordi- Astrometrica. All the information about the software. nates for an object that you wish to view. Most of the How it works and a free 100-day trial period to use it time they are never used - they just look good! prior to possible purchase. < http://www.astrometrica.at/astrometrica.html > The equatorial mount is best suited to a telescope < http://www.astrometrica.at/download.html > where the viewing positon is along its axis or for astrophotography. As many amateur telescopes are Good Observing from John. Newtonian reflectors, an equatorial mount too often causes the viewing position to become inconvenient, ------necessitating rotating the tube in its carrier or even turning the tube over end for end . Closest asteroid yet flies past Earth Jeff Hecht, New Scientist October 2, 2003 The popularity of the Dobsonian 'scope and the fact that big professional telescopes are now alt/azimuth An asteroid about the size of a small house passed just supported shows that a strong case be made for this 88,000 kilometres from the Earth by on Saturday 27 type of mount. It is inherently very stable, particular- September - the closest approach of anatural object ly when fitted on a pier. It does not need the counter- ever recorded. Geostationary communication satellites balancing weight of the German equatorial. Of circlethe Earth 42,000km from the planet's centre. course it is necessary to move in two directions to keep an object in view but this is not so great a disad- The asteroid, designated 2003 SQ222, came from vantage as it might seem. For those of us who enjoy inside the Earth's orbit and so was only spotted after it purely visual astronomy the alt/azimuth configura- had whizzed by. The first sighting was on Sunday 28 tion has many advantages. It is a simple and intu- by the Lowell Observatory Near-Earth Object Search itive mount. If you want to look left or right, or up or program in Arizona, US. down, then that is the way you move the telescope. You don't have to juggle with the slow motions to The asteroid's 1.85-year orbit is quite eccentric, indi- move quickly to another part of the sky nor find cating it cannot be a man-made object, Marsden says. yourself having to twist to some awkward position to He estimates the asteroid measured less than 10 squint into the eyepiece. With the alt/azimuth , the metres. This is too small to have posed a danger to eyepeice on a Newtonian reflector always remains at Earth, although it would have made a spectacular the same position. If you want setting circles then alti- tude and bearing scales are just as good. Their reduc- Equatorial or Alt. Azimuth? tion to right ascension and declination and vice versa by Jim Smith is simple with one of the star charting programs from the Internet which give an object's coordinates in both Almost every telescope advertised today has an equa- formats torial mount. It is not hard to see why. An instru- ment aligned along the polar axis, with a substantial An ideal alt/azimuth head would be mounted on a counterweight and sitting on a tripod, is most peo- stout pier rather than tripod and have graduated cir- ple's idea of what a proper telescope should look like. cles of 0 to 360 degrees for the azimuth and 0 to 90 degrees for the altititude (it need be no more since it The equatorial head however is a hangover from early only travels from the horizontal to the vertical). If the days. When the big telescopes of the 19th century bearings are stout enough there is no need for clamps were built they needed a mounting better than previ- or slow motions. Anything like full motor drive with ous rather crude horizontal and vertical movements computer control would be an unnecessary complica- using coarse manual systems of swivels and screw tion of an essentially simple system. threads. The obvious development was to tilt the ver- tical axis of the alt/azimuth until it pointed to the If you have an equatorially mounted Newtonian and Pole. A star once located, only needed a clock-driven would like to try an alt/azimuth mount just set the slow motion control on the polar axis to compensate polar axis to latitude 90 degrees and it becomes an for the earth's rotation, to keep it in view . Altogether azimuth bearing. The declination axis now the alti- the equatorial mounting was an enormous improve- tude bearing. You might be able to dispense with any men for the systematic investigation of the heavens. . counterweight too. If your Newtonian is in a cradle, So much so that we have been stuck with it ever since. set the altitude to some moderate angle and turn the But is it really the most suitable mount for the ama- scope tube so that the eyepiece is at a comfortable

Page 11 position. Now you can walk right round 360 degrees Comet Linear 2001 by John Fletcher and the eyepiece will remain at that same position. No more craning or contortions!

These settings may not be possible on all equatorial heads as there may be trouble with knobs or dials fouling other parts of the head. However if you can make these adjustments you will likely find observing more comfortable.

Mount Tuffley Open Day 28th September 2003 by Duncan Willoughby

On a late September Sunday afternoon the society descended en masse to John Fletchers house. This was following a kind offer that had been received from John earlier in the summer to pop along and take a look at his roboticised observatory and take a look at the famous Moore Reflector. Coordinator’s spot by Duncan Willoughby At least 25 members paid a visit and were, with a drink and a bite to eat, kindly treated by John to tour My last coordinators spot of the year always puts me his facilities, view some of his latest work, which in a reflective mood, and I also realised that I have includes an educational CD, and be shown one of his only got two more opportunities after this to report to most prized possessions, the Moore Reflecting tele- you in this slot! scope. John explained to various groups of members, how he This year instead of looking back on the great year we was currently in the middle of a project to permanent- have had again, I’d like to share with you some of my ly house the telescope in a new observatory in his thoughts about the sort of things we have lined up for back garden. The construction of which continues next year. apace! Although I am stepping down in April as coordinator, During the course of each tour he also explained how I nonetheless have some ideas that I would like to Sir Patrick Moore had made use of the telescope to progress before April and after the AGM when I no map the Moon prior to the Apollo manned missions. It was a treat to be up close and personal to such a his- torically important piece of equipment, which I no FAS Astro Calendars 2003/2004 doubt will be a source of interest and inspiration to many budding astronomers for years to come. The are now available legacy of holding onto such an important piece of astronomical history is a duty I know John will not Next year’s Astro Calendars, covering the shrink from, and the society is proud that he has been period October 2003 to December 2004, given custody of the telescope for the benefit of future have arrived! These are available to mem- generations. bers at the discounted price of £1.50 During the afternoon John showed a number of each, and copies can be bought from Rod videos, including a programme about Asteroid and Salisbury at any Society meeting, while Comets, and one about cosmic rays which included an stocks last. interview with Astronaut Charlie Duke describing his experiences in relation to the phenomena. The calendars were supplied free of charge It was all in all a full afternoon and an opportunity to to members last year, but it was agreed at catch up on news, and a chance for everyone to have a this year’s AGM that it would not be possi- chat over a glass of wine or three, and share with John ble to do so again this year, in view of our in some of his recent successes. I would like to thank higher anticipated expenses. However, John for again throwing open the doors of his home to we’re sure that members found the calen- the members, and we hope he will kindly invite us along again in the near future. dars worthwhile and will be keen to pur- chase this year’s copy. Supplies limited, so don’t miss your opportunity - buy now!

Page 12 longer hold my office. Want a holiday on Mars? Then check this out

Owing to popular demand we have been asked by Wildfowl and Wetlands Trust to repeat our successful viewing night and talk. Next year we shall hold a spring night and an autumn night as well. This, along with similar events was well received by members of the public and the organisations that we collaborated with. There has already been an early indication from the Regent Arcade management team that they would favourably consider a similar event to the Mars public display again next year.

Through next year we will be arranging more viewing evenings at Whiteshill, and hopefully we can arrange more at Bredon School. We have been approached by a Church Group in Cheltenham to hold a viewing evening and talk, and we shall hopefully collaborate with Gloucester Library to arrange a themed event at Although we haven’t got any specific ideas for a spe- a College in Gloucester. It is possible that the library cial guest speaker for next year along the lines of John will try to secure the services of a well-known guest Dobson, Dr. Allan Chapman, or Don Lind, it is always speaker to talk about a current subject in Astronomy nice to be able to do something like this. If anyone to a ticketed public audience. I have made contact knows anybody, or has a friend of a friend, or a with the library, and hopefully I shall be having a favour to call in give Callum a shout. My Mum sug- meeting before Christmas to thrash out some ideas for gested that she would like to see Brian May at the next year. society. Although I am sure his fees would be prohibi- tively expensive you never know! I have a feeling that You will remember a few months back, I brought to he may live in Gloucestershire. Does anybody have your attention the Space Walk. This walk any ideas? Our special events are an opportunity for consists of a 14-mile scale model of the us to pull out all of the stops, and really go for it and running along the towing path of the and have fun, so if anybody can suggest anything, or Canal. I have been in contact with the indeed have a special guest who they would really Tourism Manager now based in my office at British like to see attend at the society, please speak up! Waterways on ways in which the society will be able Behind the scenes Callum has made contact with a to help to enhance the image and awareness of the number of people who have been outside of the soci- walk. The kind of help I hope the society can offer will ety’s pocket, but please at least suggest people so that be similar to that that we offered to Gloucester we can investigate possibilities. Library. In the case of the library the support we offered was, where to obtain funding, specific con- Whilst there are some advanced plans in place for tacts, ideas etc. It is my hope that this sort of thing will next year, as ever it will evolve as the year progresses happen again. Certainly the society’s consultation for and possible events present themselves. I am remind- the document put before the Science and Technology ed tonight to how dynamic the solar system is. sub-committee was well prepared, and well received, Tonight’s news made reported the huge solar storm and this consultancy, I feel shows another level of brewing on the surface of the sun, and that there is a excellence for the society, which I trust we will contin- chance of aurorae. With that in mind next year is a ue next year. blank sheet, and as ever the sky is truly the limit, you never know what is around the corner! As ever have a Of practical enjoyment to the society, I continue to Merry Christmas and a prosperous New Year. Here’s scout for venues where we can hold a Star camp adja- to another successful year ahead. cent to one of the Canals that British Waterways man- ages. I hope to be able to make the "Canals on Mars" A Learner Joins idea a practical and repeatable reality. Currently I by Norman Ellis have two sites in mind which both enjoy excellent facilities, and who knows we may be able to get some When I take the dogs out at around midnight to walk boaters interested in Narrowboating Astronomy to around the race course at Cheltenham, there are no boot, if they haven’t already looked out of their boats lights nearby, so on a clear night it is ideal for star on a clear night! I have tentatively put out feelers so gazing. Looking to the North and the East the stars are with a bit of luck I should have something to report clearly set in the dark blue firmament, with the con- early next year. stellations easily identifiable - if I could remember them - but looking towards the South, only Mars is to

Page 13 be seen because of the light pollution from the street lights of Cheltenham, even though most are about 20% Discount on two miles away. All the rest of the stars have disap- pearedinto the orange haze. Before I joined the Springer Books Cotswold Astronomical Society I had never even heard of light pollution.

When I was much younger, I worked in the Post For Members of Cotswold Office Radio Research branch where we were devel- Astronomical Society oping the ground station equipment for Telstar. Although this was the first artificial communication satellite, I was more concerned with communication than anything to do with space. Later, although gettingRAF aircrew instruction on constellation recog- nitionand seeing the odd comet, I got involved with some aspects of other artificial satellites. It was only after many years, when I went on holiday and visited the NASA site in Florida and saw the enormous Saturn 5 rocket, together with other aspects of space exploration that I became interested in our solar sys- tem and what lies beyond. That visit made such an impression on me that I devised a fairly basic lecture, To get your 20% discount state that you are a with slides, about our planet neighbours and the rock- member of Cotswold Astronomical Society when ets which send probes to inspect them to present to placing your order. my own and other PROBLlS clubs, including a presen- tation to the Institutes of Physics and Electrical You can place orders by: Engineers. Apart from a disastrous performance fot Phone: freephone 00800 777 464 37, the latter, where the university projector ceased work- Faxing: +49 6221 345 4229 ing and I dropped all the slides in trying to transfer E-mailing [email protected]. them to my own projector set up in the middle of the audience, later presentations have been well received. You can view Springer’s full range of books by The Cotswold Astronomical Society exhibition in visiting their new website - springeronline.com - Cheltenham a month or so ago reminded me that our which has a practical astronomy section. solar system is but one of many and I thought that I ought to learn more. Maybe with the help of Derek's old telescope andattendance at the Society this will Comet Encke - by John Fletcher come to pass. but don't hold your breath!

Page 14 Page 15 FOR SALE 4.5 “ Equatorially Mounted Newtonian with TAL1 4.5” Equatorially Mounted Newtonian x2 Barlow, 6mm Kellner, Sun Filter x3 Barlow, 25mm Plossl, 15mm Kellner New Unused - Price £120 Good Condition - Price £75 Contact: Arron Reason No 1 Kes Mill Cot, St Marys, Chalford Stroud GL6 8NX Telephone: 01453 731566

Page 16 Page 17 Monthly Meetings Society Officers

November 17th - observing (meteors?) at Coordinator Bredon School Duncan Willoughby 69 Wellsprings Road, Longlevens November 28th/29th (T.B.C) - Viewing event Gloucester, GL2 0NJ at National Birds of Prey Centre, Newent Tel: 01452 416405

December 8th Christmas meeting Treasurer & Membership Secretary Rod Salisbury January 10th 2004 “Jets in Radio Galaxies”, Grove House Dr Martin Hardcastle, University of Bristol Christchurch Road Cheltenham, GL50 2PN February14th “Beagle 2”, Barrie Kirk, Beagle Tel: 01242 516416 2 Project Manager, Astrium Ltd Newletter Distributor February 28th and October 16th - Viewing Rosemary Salisbury (see Rod, above) evenings at the WWT Slimbridge (TBC) Events Organiser March 13th “Comets - Ancient and Modern”, Callum Potter Guy Hurst - BAA and TA The Cottage Bredon’s Hardwick Monthly meetings of the CAS are held on the Tewkesbury, GL20 7EE second Saturday of each month at Tel: 01684 773256 (home) Shurdington Church Hall, School Lane, 01242 229741 (work) Shurdington, Cheltenham, starting at 7.45 pm. Email: [email protected] Prospective new members are always welcome to come along to see what we do. Librarian and Newsletter Editor Peter Cadogan Elville House 126 The Park Cheltenham, GL50 2RQ Tel: 01242 235471 (home) 01242 582451 (work) Email: [email protected]

Web Site www.cotswoldas.org.uk Email [email protected]

The Cotswold Astronomical Society is a mem- ber of the Federation of Astronomical Societies The next issue of Mercury will be in Jan 2004. Please ensure that the editor receives all mate- rial by the 30th December. If at all possible, please submit articles in electronic form. If you would prefer to receive your issue in PDF form, please email the editor.

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