By Dave Stratton
23rd February 2005
Ed Goward – Light Pollution
Mike reminded us about the next Open Night on 11th March He also told us that 24th April was the 15th anniversary of the HST and that the event was to be marked by some special activities which the Museum was likely to be involved in. What exciting news.
Mike introduced Ed who had been coerced into giving us this talk but appeared to be very happy with the task.
Ed began by saying that light pollution was certainly a problem but one which with certain approaches could be lived with. Ed showed us a map of the UK with areas of good skies through to heavily polluted areas. Guess where we are.
Ed said there were several options. The first was to look at objects that are bright and therefore not overly affected.
He suggested the Sun was an obvious choice either projected or using high tech. stuff like HA filters. Also the Moon and planets. Ed illustrated his words with excellent slides all taken by his good self.
When looking at fainter stuff he said you could rig up a screen perhaps using a blanket or perhaps using a baseball cap with the peak positioned to avoid a nearby light getting in your eye.
He also said if you suffered from security lighting it always pays when approaching neighbours to be polite and exercise your diplomatic skills.
He moved to eyepieces and said that those fitted with cups were much better as they cut out a lot of light from the immediate area of the eye. He showed how you could make up your own cups using tape.
He also mentioned that certain filters attached to eyepieces could significantly improve the performance of an eyepiece on certain fainter objects. He said that he could even see the Veil Nebula from his garden.
He then said another option was to travel. I.e. go to a darker spot such as our own Dark Site on the Dengie Peninsular. Or perhaps takere yourself off to a special vacation site of, which he had the details of several. Or like our Ted go off to exotic places like Las Palma.
Ed also had a whole range of literature with lots of copies which we he described to us and we were invited to help ourselves.
Well what can I say it was a very interesting talk and perhaps we are not as mad as I sometimes feel we are with our fascination with the sky above.
16th February 2005
Chris Baddiley – Active Galactic NucleiMike told us about the Open Night last Saturday at the Hadleigh Castle Country Park. The weather started poorly which obviously put people off. It was estimated that 150 folk turned up. As the evening progressed it got to be 80% clear so lots of objects were seen.
Mike introduced Chris who most of us know because he has given us many talks over the years. He often stays a night or two with Ted our treasurer.
Chris’s talks are always excellent being full to bursting with super images and information by the lorry load. This was absolutely no exception. There were in the order of 200 slides many were multiple images a few had video clips to specifically show how galaxies react with one another. It is extra-ordinary that despite galaxies passing through one another. The stars themselves do not strike one another. They have their track altered massively but they do not collide. This is not ridiculous because as Chris explained if a star was the size of a pea the next one to here would be in London.
As I said above the talk was superb, there is no way I can do it justice here in print and still pay enough attention during it to enjoy it myself. So you will just have to come along.
9th February 2005
Eddie Guscott – CCD ImagingTerry introduced us to of all things a battery powered heated blanket. It was a fairly large item costing £19.98 from Woolworth’s Terry assured us it had loads of uses. It certainly was cheap so you know whom to talk to if interested.
Mike after reminding us of the Open Night this weekend introduced Eddie who over time has enthralled us with his expertise with CCD imaging.
He showed us his SBIG CCD camera this attaches to the scope ILO the eyepiece. Eddie explained that the principal of operation was very similar to a digital camera but only operating in black & white.
He explained how to connect the camera and how to focus it. He admitted that getting a good sharp image was quite difficult and improved with practice.
He spoke about signal to noise ratio. The signal being what you want - the noise being pollution. The better the ratio the longer the exposure can be. He also explained that currently the cost of colour cameras was at present too high. This issue was overcome by a technique called RGB imaging. Where red, green and blue filters are used and then combined to give a colour image.
Eddie said that because 3 colour exposures were required plus another to get rid of noise the whole business was very time consuming. This could take as long as 4 hours. This was then followed by a similar amount of time on a PC processing the final picture.
He was using M42 as a model during his talk and demonstrated various techniques to achieve certain results. It was far too complex for me to do justice to it here but many of the audience were pleased to get various ideas from Eddie.
2nd February 2005
Andy – Nebulae - Part One
Mike introduced Andy. We haven’t enjoyed one of these for quite some time, and there is more to come with Part Two on 2nd March. Andy’s talks are characterised by one thing - he does not use notes and this was no exception. He gave a PowerPoint presentation using a laptop & our digital projector. He had 40 screens, spoke on each for some ten minutes yet managed to squeeze it into 90 minutes. Impossible you may think but you should experience it for yourself.He began in a typical self deprecating manner pointing out how little he knew and inviting his learned audience to chip in as they felt the need but asked them not to expand on his comments only correct. Needless to say nobody corrected him.
He explained that a Nebula (plural nebulae) was a fuzzy patch in the night sky perhaps made up of a group of distant stars or maybe a gaseous cloud – being indistinct and/or formless. Our ancestors would have been aware of many nebulae in the sky without understanding what they were seeing. Then along came Galileo Galilei with his telescope who saw starry nebulae, realising that many of the known nebulae were star clusters. We had a few excellent images here including Pete Carson’s image of the Double Cluster. At this point Andy inserted a talk all of its own on resolution, explaining how due to diffraction a scope has difficulty resolving point sources of light. This is due to the phenomenon of Airy Discs. If two stars are close together the airy discs will merge and no amount of magnification will split the two.
The fix is however simple just get a bigger scope.
So with these to hand one Antoine Darquier Pellepoix discovered planetary nebulae initially. There was a certain amount of reclassification as earlier mistakes were rectified. Spiral Nebulae courtesy of Lord Rosse followed these using The Birr 36inch. He went on to make a 72inch, which by 1850 had identified 14 spiral nebulae but was unable to resolve them so there was as yet no understanding of their true nature. This was finally proven in 1917 by Hale.
The 100inch Hooker telescope was built at Mount Wilson in 1917. In 1924 Edwin Hubble measured the distance to M31. Andy said that some nebulae could not be resolved, there was a simple explanation - they were not starry! A lot of work was done on this by two gents namely Gustav Kirchoff & Robert Bunsen. Andy launched into another mini talk explaining about EMR (electro magnetic radiation). This involves analysing the light from stars by use of spectrometry. Eventually courtesy of Edward Barnard Dark Nebulae were discovered. At first these were thought to be holes through our galaxy as they appear as black patches but it was rationalised that this could not be the case so they must be dark clouds, which obscure the stars beyond them.
Today we know that these Dark Nebulae are vast clouds of gas & dust generally known as molecular clouds. Andy treated us to a flurry of beautiful images of examples such as M24, NGC 4402 and finished with Eddie Guscott’s Horsehead Nebula.
26th January 2005
Beginners’ Evening with Andrew on his ETX 70 & Ted on La Palma
Mike advised that he has arranged a special meeting for 23rd March on the ‘Geology of Essex’ in The Central Museum, Victoria Avenue, Southend. This is because we are denied access to the church for that evening. This will be a regular meeting in that all will be welcome but please try to arrive at 8pm sharp. Otherwise use the side entrance by the wildlife garden. .
Mike introduced Andrew who had volunteered to tell us about his acquisition of a Meade ETX 70. Andrew proved himself very quickly to be both relaxed & eloquent in his delivery, he even managed to make the very serious business of choosing a telescope funny.
He said he had bought it second hand from Alan, another member. Basically he talked us through the set up procedure by doing exactly that and explaining every step of the way as he proceeded.
He said he had had his fair share of teething problems - one was with the power supply. This involved the scope just revolving continuously. He duly resolved this. He had found Ebay to be a very reasonable place to buy accessories from.
He said the instrument would not stand too much power but was just great for larger objects like star clusters. He also mentioned his attempts to get the Starry Night software to control the scope but found the French system advocated by Terry to be rather better. He said that initially he had problems setting up the Go-To. This was because the machine needs to be pointed at certain stars so the user has to recognise those stars. Yes we know the problem. He said the scope could be acquired for £150 - £300. He had been happily buying accessories as they crossed his path some coming from our own Jim. He explained that he was happy to do this because when he upgraded they would fit t a larger scope.
Andrew said he was currently working his was through the Lunar 100. Presently on No 7.
Ted was then introduced for his talk on his recent trip to La Palma. I should point out that Ted & two pals Ian & Nik make regular trips for the purposes of indulging themselves in the splendid skies afforded by this exotic location. So he was slotted into the programme, as he is every year, to share the delights with us.
Sadly only the first night was any good at all resulting in one image of the Cone Nebula. There was a multitude of pics of dejected would be astronomers and loads of ‘mood’ views of blustering wintry landscapes. The highlight was a jam session on the local township. Where Nik proved himself to be a very good drummer. But Ted admitted this was not really his thing.
Ted filled in with loads of pictures of their fairly treacherous drive up - close to edges with icy roads to cope with. Ted also told us lots about the various professional observatories at the location.
The weather really was extraordinary. Ted made it into a humorous story adding that he was not to be put off by this disaster but if anyone could advise him of a plus 5000 feet location in Europe so her could drive there he would be forever grateful.
Suggestions on a postcard please.
On the side lines we had no fewer than 6 new people join this evening & young James one of the new people had some great advice from our experts on setting up his scope during tea break & afterwards. The Library was also doing good business in Gerald’s capable hands.
Yet another very excellent evening.
19th January 2005
Paul Cooper – Calculating Orbits
Mike showed Terry’s latest invention which takes the form of an illuminated inverted bucket on a broomstick with a astronomical object projected onto its inner surface such as to announce to innocent bystanders the object a particular scope is trained upon. So translucent buckets about 12inch diameter are wanted along with broomsticks.
Ted advised that the donations from last Saturday’s Open Night amounted to £52, This is a lot more than we thought. It will be split equally between the Country Park and ourselves.
For you information the next Open Night is February 12th.
Steve advised that the very annoying camera flashes last Saturday were the result of the Evening Echo’s support photos for their article. Unfortunately none of us has a copy so can anyone help? Steve eventually got to introduce our Paul.
Paul began in his delightfully clipped very English way of delivery to explain in simple terms how the orbits of objects like asteroids or comets an be calculated. The problem is that whilst the comet orbits the Sun it can only be observed as it close approaches the Sun and therefore the Earth. In addition Kepler’s Law defines that in a given time the area of the comets track swept will always be equal. So when the comet is far out on its trajectory it is going relatively slowly but the radius is vast so you have a long narrow area in a unit of time. However when the comet is near the Sun it is travelling very quickly and the swept area is now very wide but shallow.
At least three readings are needed to begin the calculation. One issue is that we on the Earth are also moving through space & rotating as well.
I will not attempt to include the maths here even though Paul was kind enough to lend them to me.
It would appear that with three readings and a bit of guessing or altering of values, which together with the magical calculating abilities of the modern PC can render this task relatively simple for those gifted folk who do these things. Paul gave some data he had calculated of our very own readings of Comet Machholz. They were very impressive. Paul went on to say that he is conniving with Brendan to have our website carry the calculations necessary.
There were quite a few questions at the end’ which is a function of how little they understood or how much but at least they were not asleep.
Paul managed in his very personable way to convey a very complex subject in a self-deprecating manner that charmed us all.
We had 7 new people along tonight all as a result of the Open Night. Andrew & his son Sev. Also Mary with her son James & his friend Lauren. Plus Bernadette & Sarah. They all seemed to enjoy the evening.
15th January 2005
Public Open Night at Hadleigh Castle Country Park
The event looked doomed at the start. The sky was covered in thinnish cloud. The Moon was just gleaming through. About twenty scopes were set up despite this. The public began to arrive but for the first half hour the Moon was all there was. It was spectacularly displayed from Tim’s scope and projected via our Digital Projector onto a screen. It was the star of the show without doubt. However the other instruments there included the Clubs own 16-inch dob and Jim’s 20-inch which was constantly under siege. The sky just got better and better as time went past.
Excellent event despite the gloomy start. We had 70 to 80 cars filled with about 150 people.
12th January 2005
We certainly got a flying start to the New Year with observing. It was clear, what a bonus. We had a great selection of instruments from binoculars to several 12-inch dobsonians.
The seeing remained good for the entire evening. Newcomers Di & Richard enjoyed their second meeting and brought along their excellent 12 inch Meade. Complete with binocular viewer.
Here was so much to see from Saturn with 3 of the moons on view including Titan where the Huygens Probe has just landed to the latest comet.
We really should arrange more like this.
5th January 2005
Matthew Holmes – Serenity - A British Voyage to the Moon
Mike kicked us off in this first meeting of 2005. He began by reminding us that our next Open Night is nearly upon us being scheduled for 15th January. Mike went around the room allocating objects to both willing & otherwise volunteers. The plan is to be there at about 16.45. The public are supposed to arrive at 18.00 but past experience teaches us that 17.30 is more realistic. Mike also reminded us that this weekend is scheduled for Dark Site observing . Contacts are Mike &/or Ron.
Mike then gave the floor to Dave Smith who introduced young Matt Holmes who is a year 9 student from a Maldon school.
Matt took the floor with amazing aplomb. He did not appear in any way nervous as he introduced himself and his short talk, which was a toung-in-cheek tale of a British Moon mission.
Matt explained with the aid of PowerPoint the main features of his mission, which was to be launched atop a Titan 4 rocket. Once in space the craft would be driven by the revolutionary Ion Drive system.
The plan included a ‘mole’ that would be used to burrow through the dust layer to the rock beneath. Matt explained that the surface was known to be covered by 66 feet deep layer of dust.
The mole would be transported on a six-wheeled ‘rover’.
Matt was sad to report that despite writing to some of the major world agencies involved in space exploration he had received no support to date. Therefore he did not anticipate an early launch date.
Funding had however allowed him to build a rather large-scale model of his vehicle, which he proudly held up for us all to see. The best bit of all was his Mum’s donation, which was her collapable kitchen colander which was doing sterling service having been recycled as a splendid radio dish mounted in the front.
Matt finished his delightful talk with the news that some of his school friends who had already experienced it had wished him well for the trip.
We then got to the serious business of the evening and put the kettles on. The turnout tonight was excellent, about 40 was the estimate, with four new faces and two who have been before.
We settled down to about ten different groups talking happily amongst ourselves. Brilliant.