WADHURST ASTRONOMICAL SOCIETY
JUNE NEWSLETTER 2007
INDEX: MEETINGS, OTHER NEWS, CONTACTS
VISIT TO BELMONT HOUSE
the Society's May meeting Phil Berry announced that the visit to see the largest
private collection of clocks is to take place on Saturday 22 September
would meet at Belmont House at 1030 for coffee and biscuits and then be shown
round the clock collection beginning at 1100.
The tour will last about two hours but we would need to find our own way
there. Members may wish to arrange to travel together where
House is about 4 miles south, southeast of the town of Faversham, on Throwley
Road. More details of the location will follow later.
we had thought we would visit Greenwich Observatory later the same day, but it
is felt that this would be too much for a Saturday, so we are hoping to arrange
a separate visit to Greenwich later when we may be able to visit the newly
opened planetarium as well.
A total of 17 members have so far said that they would wish to come to Belmont House and have ticked their name on the list made available at the meetings. The members listed in alphabetical order as attending on Saturday 22 September are as follows:
If you were absent or unaware of the list and your name does not appear but wish to attend or are now no longer able to attend please let Phil know by the July meeting at the latest, or by email before, as final numbers are required.
given by Nik Szymanek at the Society's May meeting
members know and admire the astro-pictures of Nik Szymanek and at the Society's
May meeting he explained some of the ways in which he achieves those remarkable
results with the aid of modern computer software.
his talk Nik displayed the output from his laptop on a digital projector
enabling us to watch as he manipulated images with various programmes into
images that revealed details that weren't apparent to begin with.
mainly uses two software programmes, Adobe Photoshop CS and Maxlm DL's DDP
(Digital Development process).
an introduction to what can be done, we were shown a scanned film image of the
comet Hale-Bopp taken during its close pass in 1997.
The film image suffered from a lot of low-pressure sodium light pollution
as a very obvious greenish background resulting in an image one would have
using Photoshop, Nik demonstrated the programmes ability to correct for the
light pollution in the dark part of the background sky by separating the image
into its three channels, red, green and blue, then correcting the background sky
on each to black.
he used gamma control to stretch the darker parts of the image, where much of
the interesting detail lies but without compressing the brighter parts too much. The results enabled us to see more detail in the darker parts
of the tail without losing too much in the head of the comet.
By further enhancing the image in the three separate colour channels and
working particularly on the blue channel it was possible to resolve the comet's
separate blue ion tail.
the image was sharpened up using the Photoshop "unsharp" tool.
By comparing this image with the original was very impressive.
A useful advantage is that the unsharp tool can be masked to only operate
on certain selected areas of the image.
the History List it is possible to go back through performed adjustments to an
earlier point, allowing further corrections to be made.
another example, the star cluster M92 in the Hercules constellation is very
contrasty and in preserving the fainter stars there is the danger of losing
detail in the brighter central cluster. Here,
we saw how different transfer curves can keep the bright areas from crushing
whilst enhancing only the darker areas. There
are three basic curves; linear, gamma and logarithmic, all with their special
particular transfer curve that Nik uses is part of the Maxlm D4 software
programme. In this programme there is a facility called "Screen
Stretch" where another curve lies somewhere between the gamma and
logarithmic curves and is called the Digital Development Process curve.
This was created by an amateur astronomer in Japan.
DDP on the Black Eye galaxy, M64, Nik showed how it was possible to really bring
out the fainter stars whilst preserving great detail in the heart of the galaxy
by carefully using the Screen stretch.
went on to say that in most of his work, he uses many short exposures that can
be combined to make one long exposure. One
single long exposure can result in it being ruined, for example by a passing
aircraft. Noise is also added
during an exposure at the square root of the whole image.
original image of M87 in Virgo showed a diffused area, which by using Screen
Stretch revealed a jet that is said to be travelling away from the galaxy at the
speed of light. This is normally
not seen due to over exposure.
imaging the Moon, Screen Stretch can also be used to increase the contrast,
producing the effect of apparently sharpening the craters.
tells of when professional astronomers on La Palma were given a new imaging
camera to assess, were only permitted to use the telescope for ten minutes.
During this time they tried to image M51, the Whirlpool galaxy, but
managed 5-minute exposures only in red and green. Some time later, the King of Spain was being shown around the
observatory and was asked if there was anything he might like to see.
It was suggested that he looked at M51 giving the astronomers a chance to
finally get their remaining 5-minute blue exposure.
Whirlpool galaxy has an arm stretching out on one side with a diffused blob at
the end of it. By astute use of DDP
it was possible to show the detail of the blob and it could now be clearly seen
as a separate galaxy that is believed to have passed close by M51 and had drawn
out some of the material in the arm.
Photoshop we were shown another trick, this time using layers.
For this example two identical images of NGC 2903, a spiral galaxy in the
constellation of Leo, were placed one over the other so that only the top layer
was visible. This image was then
enhanced to bring out the detail of the fainter stars but inevitably crushing
out detail in the central core at the same time.
Then by using the erasing tool with a feathered edge the centre was
gently erased, revealing the layer underneath with all the original detail of
the core. The combined image showed
details that could not be appreciated in the original image.
example of the use of Photoshop was shown using an image of M82, a starburst
galaxy. One of the images was in Hydrogen Alpha light, producing a
red image. This was enhanced and
placed on the clipboard whilst the remaining two channels were adjusted for
optimum background black sky and now showing detail in the dark lanes of the
galaxy. The red image was pasted
back from the clipboard, resulting was a very much clearer image of M82.
were also shown how noise can be reduced by using the De-speckle tool on each of
the colour channels before recombining them.
20th June 2007 This will be
an open and informal evening when we have the opportunity to talk to other
number of telescopes will be at the meeting for discussion and demonstration of
how they get used.
member able to give a short talk will be very welcome and should contact Phil
Berry who would be delighted to hear from them.
18th July 2007 George
Satterthwaite will be giving a talk about "George Airy and His Contribution
to Positional Astronomy".
is no meeting of the Society in August, but once again, we have been kindly
invited to an Astro Barbecue hosted by Michael Harte and his wife at Greenman
Farm on Saturday 25th August 2007.
Farm, Wadhurst is on the south side of the B2099 immediately to the west of the
railway over-bridge. All Society
members are invited and Michael suggests that members aim to arrive at about
will only need to bring your own food and drink, as everything else will be
previous years this has been a very enjoyable event and gives members a chance
to meet others in a relaxed and pleasant atmosphere.
are invited to bring telescopes, binoculars and anything else of interest, but
Wednesday 19th September 2007 George Sallitt will be giving a talk about "Webcams", a subject that will interest a number of members keen to get involved with this cheaper but satisfying method of imaging.
Wednesday 19th September 2007 George Sallitt will be giving a talk about "Webcams", a subject that will interest a number of members keen to get involved with this cheaper but still satisfying method of imaging.
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Seaney has an eight-inch LX 10 reflecting telescope for sale.
is an ideal telescope for the more serious amateur astronomer and would provide
the opportunity to get involved in more serious observing.
telescope is in excellent condition and has its own travelling box.
It has an equatorial battery driven mount with hand controls.
The instrument takes standard one-and-a-quarter-inch eyepieces and comes
with a 40 mm eyepiece.
telescope comes with a heavy metal tripod for good stability.
is asking £450, which is very reasonable.
JUNE NIGHT SKY
should be visible at magnitude 0.5 in the north-west at the very beginning of
the month. Always wait until the Sun has set before sweeping for it with optical
reaches greatest eastern elongation on June 9th when its magnitude will be -4.3.
It is unmistakable in the twilight sky setting some three hours after the Sun.
is still a morning object, rising around 02.00 BST, in the constellation of
Pisces (the fishes) but moves into Aries (the ram) later in the month.
Observations are hampered by the planet lying relatively low in the sky.
is an evening object at magnitude -2.6 in the constellation of Ophiuchus (the
serpent bearer). By the middle of the month it rises well before the Sun has
set, although it is never more than 17º above the horizon. I observed it at
22.45 BST in the middle of May and was able to see the four largest moons and
some surface markings, although the unsteadiness of the atmosphere at that
elevation makes very detailed observations difficult. Despite this it is still
worth following the progress of the moons from night to night.
is still an evening object at magnitude 0.6 in Leo (the lion). On June 30th
Saturn and Venus pass close to each other (within about one degree), which could
present an opportunity for astro-imagers.
For this months occultations I've included five events for stars (two of them double) down to about mag 7 that occur before midnight. DD indicates that the star disappears at the dark limb of the moon. All times are in BST.
|Mon 25th June||22.07||194 Lib||6.8||DD|
|Mon 25th June||22.09||194 Lib||6.6||DD|
|Tue 26th June||21.41||177 Lib||6.5||DD|
|Thur 28th June||23.32||179 Oph||6.6||DD|
|Thur 28th June||23.32||179 Oph||6.7||DD|
Occultation of Venus
There is also a daylight occultation of Venus by the crescent Moon, which should be an easy event even in binoculars. Be careful not to sweep around the sky and inadvertently look at the Sun! Times are in BST. RB indicates a re-appearance on the bright limb.
|Mon 18th June||15.02||Venus||-4.3||DD|
|Mon 18th June||16.22||Venus||-4.3||RB|
NASA SPACE PLACE
Ions of Dawn
Patrick L. Barry
summer, NASA will launch a probe bound for two unexplored worlds in our solar
system's asteroid belt-giant asteroids Ceres and Vesta. The probe, called Dawn,
will orbit first one body and then the other in a never-before-attempted
has never been attempted, in part, because this mission would be virtually
impossible with conventional propulsion. "Even if we were just going to go
to Vesta, we would need one of the largest rockets that the U.S. has to carry
all that propellant," says Marc Rayman, Project System Engineer for Dawn at
JPL. Travelling to both worlds in one mission would require an even bigger
is a trip that calls for the unconventional. "We're using ion
propulsion," says Rayman.
ion engines for the Dawn spacecraft proved themselves aboard an earlier,
experimental mission known as Deep Space 1 (DS1). Because ion propulsion is a
relatively new technology that's very different from conventional rockets, it
was a perfect candidate for DS1, a part of NASA's New Millennium Program, which
flight-tests new technologies so that missions such as Dawn can use those
fact that those same engines are now making the Dawn mission possible shows that
New Millennium accomplished what it set out to," Rayman says.
engines work on a principle different from conventional rockets. A normal rocket
engine burns a chemical fuel to produce thrust. An ion engine doesn't burn
anything; a strong electric field in the engine propels charged atoms such as
xenon to very high speed. The thrust produced is tiny-roughly equivalent to the
weight of a piece of paper-but over time, it can generate as much speed as a
conventional rocket while using only about 1/10 as much propellant.
Dawn will need lots of propulsion. It must first climb into Vesta's orbit, which
is tilted about 7 degrees from the plane of the solar system. After studying
Vesta, it will have to escape its gravity and manoeuvre to insert itself in an
orbit around Ceres-the first spacecraft to orbit two distant bodies. Dawn's
up-close views of these worlds will help scientists understand the early solar
remnants from the time the planets were being formed," Rayman says.
"They have preserved a record of the conditions at the dawn of the solar
out about other New Millennium Program validated technologies and how they are
being used in science missions at:
(At the time of writing the Newsletter, I could not make this site work. Editor)
you're there, you can also download "Professor Starr's Dream Trip," a
storybook for grown-ups about how ion propulsion enabled a scientist's dream of
visiting the asteroids come true. A
simpler children's version is available at: http://spaceplace.nasa.gov/en/kids/nmp/starr.
article was provided by the Jet Propulsion Laboratory, California Institute of
Technology, under a contract with the National Aeronautics and Space
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Chairman John Vale-Taylor firstname.lastname@example.org
Phil Berry 01892 783544 email@example.com
Mike Wyles 01892 542863
Website Michael Harte 01892 783292
Newsletter Editor Geoff Rathbone
Any material for inclusion in the July Newsletter should be with the Editor by June 28th 2007
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