WADHURST ASTRONOMICAL SOCIETY

MARCH NEWSLETTER 2008

INDEX: MEETINGS, OTHER NEWS, CONTACTS

MEETINGS

COMMITTEE MEETING      

The Committee are respectfully reminded that there is a meeting of the Committee on Monday 31st of March starting at 1930.  Again, the venue will be the Abergavenny Arms in Frant.

FEBRUARY MEETING

The Tim Bance Interview

By John Vale-Taylor

Tim Bance is a long-standing member of the Society with a huge reputation for telescoping-making and observing, and is also a past Chairman.  But he also restores furniture as well as having responsibility for the huge gardens at The Place in the village of Leigh.  Recently his commitments have meant that he rarely has the opportunity to attend meetings.

John Vale-Taylor, our present Chairman, had the excellent idea of reporting an interview with Tim illustrating it with slides.  Sadly Tim was unable to be present but John told a remarkable story of Tim's background and activities.

Tim begins each day at 0530 to deliver a paper-round!  He is also a qualified cricket umpire...

John began by showing a number of slides taken in Tim's workshop in the old tack room of the stables.  A number of photographs revealed the intricate cane work and chairs being restored to their former glory.  Another surprising item of furniture was a dining table - that had once been a mortuary table!

John now turned to Tim's achievements in the world of amateur astronomy, beginning by showing a photograph of an 18-inch truss tube version of a Dobsonian built by Tim.

In 1997 Tim became interested in astronomy and purchased a four-and-a-half-inch Tasco reflecting telescope but was rather disappointed with its performance.

It was at about this stage that he joined the Wadhurst Astronomical Society.  A member, Murray Barber, introduced him to the Norfolk Star Party where many amateurs discussed equipment and observing techniques under clear night skies.

Tim returned to build his own 10-inch reflector tube employing circles and worm drives from Beacon Hill and used a 6-inch reflector-guiding telescope.  The whole was housed in a 10' by 10' shed built in a walled garden.

This system was used successfully for astro-photography.

For longer trips Tim obtained a 5-inch refractor that enabled him to pursue his interest overseas.

John mentioned that Tim had also built an 18-inch telescope for a friend, buying many of the parts form the United States.

Tim's "bible" is "The Dobsonian Telescope" by David Kreige and Richard Berry, a practical manual for building large aperture telescopes.

John then described the actual building of a Dobsonian, starting with the box frame at the bottom with a Lazy Susan ball race and PCFE to provide an almost frictionless support for the main tube.

A box that held the main mirror was supported on either side by half-circles that slid on the P.T.F.E. support.

A view of the underside of the mirror box showed the mounting points.  John later demonstrated a computer programme called PLOP that that gave the exact points that should be used to reduce to a minimum the distorting effects of the weight on the glass mirror.

Adjusting screws beneath the mirror were provided to enable the final setting of the mirror when lining up and collimating.

Also housed beneath the mirror was an electric fan whose purpose was to keep the mirror at a stable temperature.

The "spider" holding the flat mirror, and the eyepiece was housed at the other end of the telescope-tube, which was held in place with rods rather than a solid tube so reducing the weight although these tubes were covered in water-pipe cladding to reduce condensation.

Having taken care to reduce the weight, it was still necessary to use diving weights to balance the telescope.

The telescope used a Telrad eyepiece where the observer lines up a red spot with the celestial object providing a very effective way of lining the telescope up with the object to be observed.

Tim has also visited star parties in the United States where they were using 24-inch and 30-inch telescopes.

Because the balancing weights added to luggage excess, members of the star party buried them beneath the surface of the site ready to be dug up again on their next visit.

John Vale-Taylor concluded with an introduction to his own fascinating experiences in telescope making, beginning with his first telescope which used a 6-inch mirror mounted in an 8-inch flu pipe and using a gun-sight for the eyepiece.  The whole was set on an equatorial mount made of welded square section tube.

He then briefly described his engineering career mainly in optics.  He gave an interesting history of Vicker's Instruments from their beginning in St. Dunstan's church on Fleet Street.  

We were taken on a breathtaking tour of the many aspects of John's work from microscopes and lens making machines to the making of a beautiful Communion Table for a Lady Chapel incorporating a cross with mounts for candles.

John concluded his talk by reminding members that the Society possesses a number of telescopes, which are available for members to borrow.  One is a small Dobsonian and there is also the Ian Reeves Memorial 4-inch refractor Konus telescope and tripod.  The refractor has an equatorial mount but does not have a drive.  It comes with its own travelling case.

MARCH MEETING

Wednesday 19th March 2008 A welcome return of Konrad Malin-Smith with a talk about "The Magellanic Clouds".  This takes us just outside our own galaxy to two of the Milky Way's closest neighbours in space.

The meeting begins at 1930 although members are invited to arrive anytime after 1900.  This is a good time to exchange ideas and discuss problems.

The venue as always is in the Upper Room of the Methodist Church at the east end of Wadhurst Lower High Street, opposite Uplands College.  (For those with SatNav -  the  Post code is TN5 6AX)

FUTURE MEETINGS & EVENTS

Wednesday 16th April 2008 Greg Smye-Rumsby gives a talk he has entitled "Bits and Bobs".

Wednesday 21st May 2008 Our own Brian Mills who contributes the excellent Sky Notes each month is giving a talk about "Occultations".

During June:  A visit is being arranged to visit the Great Transit Circle at Greenwich Observatory.  This will be either Friday 13th or 20th of June.  See separate note below under Other News & Information.

Wednesday 18th June 2008 Because this is one of the shortest nights of the year, in recent years this has become a members' evening when we can bring telescopes, binoculars and other aids to amateur astronomy to chat about their use and discuss problems.  There will also be a short video on an astronomical subject.  More info. nearer our June meeting.

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  OTHER NEWS

VISIT TO THE GREAT TRANSIT CIRCLE AT GREENWICH

Once again, Phil Berry has been working hard.  He has been in touch with Gilbert Satterthwaite who is willing to show a group round the Great Transit Circle at the Greenwich Observatory at the Maritime Museum.  The favoured date for the visit would be Friday 20th of June 2008, although a back-up date of Friday 13th of June has also been proposed.

Greenwich are reluctant to promise a date for us as they do not like booking up too far in advance.  However, Gilbert can not see that there would be any reason why our visit on the 20th June would affect the ROG but just in case we have a back up date of lucky Friday 13th of June.

At the March meeting it is hoped that we can get some idea the number of members interested in taking part.  Members could also show their interest by contacting either Phil Berry or Geoff Rathbone.  (Contact details at the end of the Newsletter)

The suggested approximate itinerary would be:

10:15 Meet in car park adjacent to Flamsteed House in Park.

10:30 Start tour of Flamsteed House and the Octagon Room with a short stop for the Time Gallery.

Gilbert would then like to take us a chronological tour of instruments starting with Flamsteed's (which are no longer in situ but Gilbert will show us where they went), Halley's instruments and the developments up until the Airy instruments including the main Airy Transit Telescope and how Gilbert himself used to use the instrument. The breadth of this display is apparently unique in the world.

Gilbert will then briefly show us the 28" Refractor in the main dome.

12:30 Break for lunch.

In the afternoon we would be on our own and have free time to go back to the Time Galleries or go to the Old Planetarium in the South Building where there is a large exhibition on Space which can take quite a while to go around at our own pace.

After this we could then meet up and have a group visit to the New Peter Harrison Planetarium (accessed through the Old Planetarium South Building), which will be a bit cheaper for entrance if we are still in sufficient numbers.

There are different shows during the day, these are:

Black Holes: The other side of Infinity.

Weekdays 13:00, and 15:00

In this spectacular new show, discover the early universe, witness star birth and death and the collision of galaxies and fly into a massive black hole lurking at the hear of the Milky Way. Narrated by Liam Neeson.

Sky Tonight Live.

Weekdays 16:00

Presented live by a Royal Observatory astronomer, you will be taken on a tour of what you can see for yourself in tonight's night sky.

Star Life.

Daily: 14.00

This visually-stunning show looks at the lives of stars - how they are born, grow up, grow old and die; how black-holes and pulsars form and how beautiful clouds of glowing gas come into existence. Hosted by real astronomers who are available to answer questions after the main programme.  Gilbert thought that the "Sky Tonight Live" was good as it was presented live by an astronomer. It is at 16:00.  It would be a fitting conclusion to our visit.

TELESCOPE MAKING SUB-GROUP

Following the note in the February Newsletter with regard to a Telescope Making Sub-Group within the Society, some discussion took place at the February meeting.  It was suggested that any member interested in getting together to explore setting up such a group is invited to come along to Angus MacDonald's home in the Mayfield area during the evening of Wednesday the 12th of March.

The idea would be to pool ideas and share skills and experiences.  No one needs to have special talents, just an interest.Can anyone interested in coming please give me a call:

Geoff Rathbone on 01959 524727

(email: Geoff@rathbone007.fsnet.co.uk)

SUBSCRIPTION FOR THE CURRENT YEAR

The current session of the Society began on 1st of January.

The Treasurer, Mike Wyles, is ready to accept subscriptions, which are the same as previous years at £15 per member and £20 for two members in the same family.

Mike prefers to receive a cheque payable to "Wadhurst Astronomical Society" although he will willingly take cash.  If it is more convenient, subscriptions can be sent direct to him at:

Mr. M. Wyles, 31 Rowan Tree Road, Tunbridge Wells, Kent TN2 5PZ

THE "HELP LIST"

At the monthly meetings, Phil Berry has introduced a clip-board with a sheet headed "Help List" intended for anyone asking advice.  It has been used successfully and members are reminded to use the list as much as possible.  It can be useful for discussion purposes as well as hopefully providing answers.

SKY NOTES FOR MARCH

Planets

Mercury will be too close to the horizon to be easily observed this month.

Venus is lost in the glare of the Sun and is also not visible this month.

Mars is still easy to find in Gemini (the twins) close to the Auriga/Taurus/Orion borders although its brightness and apparent size are both decreasing as we move further apart. A large telescope will be needed to see any surface detail.

Jupiter is a morning object in Sagittarius (the archer) at magnitude -2.0. Unfortunately it is (and will remain) low in the sky as seen from the UK. By the middle of the month it rises at 03.45, about 2 hours before the Sun. Jupiter's four brightest moons are easy binocular objects and their collective movements can be fascinating to watch.

Saturn is superbly placed for observation being visible throughout the night, setting just before sunrise. It shines at magnitude +0.2 just below the "belly" of Leo (the lion). Saturn's brightest moon (Titan) can be easily seen in a small telescope at magnitude +7.0 on March 6th, 14th, 22nd and 30th.

Lunar Occultations

Graze Occultation

On Friday 14th March there will be a graze occultation, of a magnitude 6 star in the constellation of Gemini, visible from an area that is reasonably close by. The event occurs at around 21.57 hrs GMT when the star "grazes" past the dark northern limb of the 54% illuminated waxing moon. Hopefully, it will disappear and reappear as it passes between the lunar mountains and valleys as seen from Earth. Timings of grazes help astronomers to build up and enhance their knowledge of those areas around the moon's limb where these events occur.

The star in question, SAO 77837, is known to be a double although it can't be seen in a telescope as such. It is possible that the star may appear to fade and brighten if only one element of the double is occulted. Observers located south of the graze track would expect to see a disappearance followed a little later by a re-appearance, possibly both on the dark limb depending on how far south of the track they were. Observers north of the track would expect to see the star just miss the moon's limb.

The tracks of visibility of these events are very narrow and location of observers is critical to trying to build up a profile of the limb. To this end we are hoping to assemble a group of observers armed with suitable telescopes and stopwatches who would be interested in taking part in such an enterprise and who would be located at pre-determined positions perpendicular to the track. The nearest passage of this track to Wadhurst is as it crosses the A28 roughly midway between High Halden and Bethersden although before it reaches us it passes through South London, Lullingstone Castle, Wateringbury and Headcorn.

brian@wkrcc.co.uk

or 01732 832691. I would suggest that if you are uncomfortable about being out alone at night in an unpopulated area then arrange to have a friend come with you. In any case it is always useful to have some help with you for when things go awry!

Phases of the Moon

ISS

Below are details of the most favourable passes of the ISS this month. The information given is for when it is at maximum altitude, so it is best to look a few minutes before this time. Full details of visibility can be found at:

www.heavens-above.com

Don't forget - BST begins at 02.00 on Sunday March 30th.

Brian Mills

NASA SPACE PLACE

Invisible Spiral Arms

by Patrick Barry

At one time or another, we've all stared at beautiful images of spiral galaxies, daydreaming about the billions of stars and countless worlds they contain. What mysteries-and even life forms-must lurk within those vast disks?

Now consider this: many of the galaxies you've seen are actually much larger than they appear. NASA's Galaxy Evolution Explorer, a space telescope that "sees" invisible, ultraviolet light, has revealed that roughly 20 percent of nearby galaxies have spiral arms that extend far beyond the galaxies' apparent edges. Some of these galaxies are more than three times larger than they appear in images taken by ordinary visible-light telescopes.

"Astronomers have been observing some of these galaxies for many, many years, and all that time, there was a whole side to these galaxies that they simply couldn't see," says Patrick Morrissey, an astronomer at Caltech in Pasadena, California, who collaborates at JPL.

The extended arms of these galaxies are too dim in visible light for most telescopes to detect, but they emit a greater amount of UV light. Also, the cosmic background is much darker at UV wavelengths than it is for visible light. "Because the sky is essentially black in the UV, far-UV enables you to see these very faint arms around the outsides of galaxies," Morrissey explains.

These "invisible arms" are made of mostly young stars shining brightly at UV wavelengths. Why UV? Because the stars are so hot. Young stars burn their nuclear fuel with impetuous speed, making them hotter and bluer than older, cooler stars such as the sun. (Think of a candle: blue flames are hotter than red ones.) Ultraviolet is a sort of "ultra-blue" that reveals the youngest, hottest stars of all.

"That's the basic idea behind the Galaxy Evolution Explorer in the first place. By observing the UV glow of young stars, we can see where star formation is active," Morrissey says.

The discovery of these extended arms provides fresh clues for scientists about how some galaxies form and evolve, a hot question right now in astronomy. For example, a burst of star formation so far from the galaxies' denser centres may have started because of the gravity of neighbouring galaxies that passed too close. But in many cases, the neighbouring galaxies have not themselves sprouted extended arms, an observation that remains to be explained. The Galaxy Evolution Explorer reveals one mystery after another!

"How much else is out there that we don't know about?" Morrissey asks. "It makes you wonder."

Spread the wonder by seeing for yourself some of these UV images at:

www.galex.caltech.edu

Also, Chris Martin, principle scientist for Galaxy Evolution Explorer -or rather his cartoon alter-ego-gives kids a great introduction to ultraviolet astronomy at:

spaceplace.nasa.gov/en/kids/live#martin

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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CONTACTS

Chairman   John Vale-Taylor 

Phil Berry  01892 783544

Treasurer  Mike Wyles  01892 542863

Publicity & Website  Michael Harte  01892 783292

Any material for inclusion in the March 2008 Newsletter should be with the Editor by March 28th  2008

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