MEETINGS

JUNE MEETING

As in previous years, and since these are the shortest nights of the year, the June meeting is held open to members as a Telescope Evening when telescopes and equipment of interest to other members is welcome.

The meeting began with John Vale-Taylor giving an overview of the Newtonian Reflector and then briefly described the clever construction of his own “skeleton” style 6-inch reflector.

He went on to demonstrate how to collimate a Newtonian using a laser collimator, stressing the importance to finding and marking the centre point of the main mirror.

John explained how all the elements had to be aligned in a particular order to achieve correct collimation.

In the June Newsletter there was a report of the Angus Meeting which encourages a hands-on approach to astronomical equipment, in which Angus Macdonald introduced the idea of adapting a Dobsonian mounted telescope for use by the observer which obviates the need to move the actual tube.

Angus had brought his Dobsonian to the meeting and described the reasoning behind the construction of the modifications. He explained that his interest had been aroused in finding a solution to allow viewing through his telescope when he had experienced repeated back pain when moving and setting up the telescope.

He demonstrated how, with the addition of an optically flat mirror in front of the tube (angled at 45 degrees) it was possible to rotate it and view the entire sky from a seated position with the telescope in a horizontal plane.

A number of questions were asked and members had the opportunity to try out the instrument later during the tea break.

Following Angus, Phil Berry gave a short presentation on the subject of occultations. At a previous meeting, Brian Mills had given a talk on the subject and Phil said he had been bitten by the bug and was keen to try out observations for himself.

He gave a brief overview of the various types of lunar occultation; e.g. “Total” and “Grazing”, and showed slides to demonstrate how the moon’s shadow was actual size on Earth because stars are so far away that their light rays are considered parallel. He described the placing of observers to see a graze occultation.

Phil then discussed asteroidal occultations and gave some impressive examples of work by amateurs who had been able to determine in some detail, the size and two-dimensional shape of asteroids by the occultation method.

He described some new gadgets he had acquired and spoke about using video cameras with accurate time overlays to record such events.

Here are the URLs Phil referred to during his presentation:

• http://www.occultations.net/

(An Introduction to Astronomy Occultations)

• http://www.occultations.org/

(International Occultation Timing Association – an introduction to accurate timings necessary for Occultation Observing)

• http://www.pic-osd.com/

(GPS Video Overlay Units – Hardware to aid accurate timing of Occultations)

• http://www.lunar-occultations.com/iota/occult4.htm

(Occultation Prediction Software)

Brian Mills then spoke about the construction of his observatory in Hildenborough where the recent Angus Group meeting had been held.

He showed slides of the construction from foundations to completion and then described how he had replaced the original dome with a lighter alternative and how he had suffered a selection of broken ribs when he fell from a stepladder during the process.

He finished by showing a picture of his other observatory – the roof of his bungalow! He described how he climbs onto the roof every July and August to get a first class view of the Perseids meteor shower.

Brian also mentioned how he is prone to dropping off (to sleep – not off the roof) whilst observing and said that on one occasion he began a meteor watch under clear skies only to nod off and awaken with the sky completely cloudy!

Following the tea break our Director of Observations, Brian Mills, gave a brief presentation about the night sky. He reminded those present about how to find Boötes and Corona Borealis and how to use these to find Hercules.

From Hercules it was possible to find Antares, the brightest star in Scorpio, which was visible at this time of year although it was quite close to the horizon. From there, the constellations of Libra, Serpens and Orphiuchus could all be fund.

Brian described briefly the globular cluster in Hercules (M13) and said how Harlow Shapley had shown that Cepheid variables could be used as standard candles to determine the distance of such clusters.

He then showed maps of the current locations of Saturn and Jupiter and spoke briefly about some upcoming lunar occultations that would be easily viewable with the Society’s telescopes, should anyone care to borrow them.

He closed by mentioning the total eclipse that will occur on July 22^nd and said that live feeds would again be available via the Internet.

Brian refers to this in “The July Sky Notes”

JULY MEETING

Wednesday 15th July 2009 “The Virtual Observatory”. Five years ago John Murrell gave an excellent talk about accessing the vast amount of data available on the internet. At the July meeting, John will be giving more information on the subject with a lot of updates. John Murrell is a member of the Croydon Astronomical Society and it is worth visiting his web site at:

http://johnmurrell.org.uk/

The meeting begins at 1930 although members are invited to arrive anytime after 1900 as this is a good time to exchange ideas and discuss problems and relax before the talk.

The venue as always is in the Upper Room of the Methodist Church at the east end of Wadhurst Lower High Street, and opposite the entrance to Uplands College. (For those with SatNav – the post code is TN5 6AT)

FUTURE MEETINGS

Saturday 29^th August 2009 – Worth putting in your diary. There is no meeting of the Society in August but Michael Harte and his wife Claire have offered to host an Astro-barbecue at Greenman Farm.

In the past some of us have taken along telescopes, binoculars and anything else we think would be useful to see the night sky in late August.

In the past the weather has been variable so this year we must be owed a good clear evening.

Any member of the Society is welcome to bring drink and food to cook on a barbecue and then take advantage of the darkening skies to view whatever is in the sky at that time.

Michael suggests that members aim to arrive about 1900

There will be further details in the August Newsletter.

Wednesday 16th September 2009 – “The Apollo Programme – Missions 13 to 17” This is a continuation of the talk given by Rob Cray in March when he told us about the beginnings of the fascinating US Lunar exploration programme.

Wednesday 21^st October 2009 - “Astro-archaeology in the British Isles”; A talk by Bob Seaney, a well known member of the Society who has given a number of talks in the past. Bob has been doing his own research for some time and reveals what he has learnt.

OTHER NEWS AND INFORMATION

SKY NOTES FOR JULY

Planets

Mercury is not visible during July, passing through superior conjunction on the 14^th. This is where Mercury, the Sun and the Earth all line up with Mercury on the far side of the Sun (behind it).

Venus is a morning object at magnitude -4.0 rising three hours ahead of the Sun by the middle of the month, lying in the constellation of Taurus.

Mars is a morning object (also in Taurus) at magnitude +1.1 rising just over three hours before the Sun. For the rest of this year Mars will increase in both magnitude and apparent diameter.

Jupiter on the Aquarius/Capricornus borders rises around 22.30 BST by the middle of the month although it never rises very high above the horizon. This is because at this time of year the ecliptic is low down during the hours of darkness. However, to compensate for this Jupiter shines at magnitude -2.7. On July 10^th it passes around half a degree south of Neptune (at magnitude +7.8) making it an ideal time to locate one of the outer planets.

Saturn is still just visible in the western sky but is gradually being absorbed by the twilight. It shines at magnitude +1.1 in Leo, very much in the same position as for the last few months as shown by the crosshairs below. By the end of the month it sets by around 22.00 BST.

Lunar Occultations

As usual in the table I’ve only included events for stars down to around magnitude 7.5 that occur before midnight. DD = disappearance at the dark limb and RD = re-appearance at the dark limb. Times are BST.

July	Time	Star	Mag.	Ph	PA °
1^st	21.35	SAO 158468	6.9	DD	56
3^rd	21.58	SAO 184047	7.5	DD	120
3^rd	22.46	SAO 184068	5.0	DD	30
27^th	21.09	SAO 157778	6.9	DD	42
30^th	23.43	SAO 183854	4.6	DD	121

Lunar Occultations of the Pleiades

In the early hours of Saturday July 18^th the Moon passes in front of M45, the Pleiades open cluster in Taurus. There are a whole series of events (24 in total) that morning, but for anyone interested I have listed the brightest below. For those who live further north and west there is the chance to see a grazing occultation of Alcyone. DB = disappearance at the dark limb. Times are BST.

Time	Star	Mag.	Ph	PA °
02.59	Alcyone	2.8	DB	5
03.00	Merope	4.1	RD	294
03.19	Alcyone	2.8	RD	322
04.10	Pleione	5.1	RD	293
04.11	Atlas	3.6	RD	274

Phases of the Moon for July

For convenience I have added the rising and setting times (in BST) for the phases listed below.

Full	Last ¼	New	First ¼
7^th	15^th	22^nd	28^th
21.37	23.41	05.21	13.55	Rise
04.31	14.06	21.17	22.58	Set

Meteors

One of the more productive showers of the year, the Perseids, begins on July 23^rd. The radiant lies fairly low down in the north east at the start, but gradually gains altitude as the shower progresses towards maximum. This means that in the early part of the evening, many events are lost either below the horizon or into the haze that often prevails if the weather has been hot. However, it is still an excellent observational target as the Perseids contain a large proportion of bright and fast meteors with many leaving ionised trains.

ISS

There are a large number of passes of the ISS as seen from Wadhurst this month. I have only included those that attain reasonable altitude and occur before midnight. See www.heavens-above.com for a complete list of all passes. Please remember that the time below is when the ISS is at maximum altitude, so you should begin looking a few minutes beforehand. Times are BST.

Date July	Mag	Time BST	Alt.	Az.
6^th	-2.5	23.14	30	SSE
7^th	-3.4	23.38	59	SSE
8^th	-2.6	22.27	31	SSE
9^th	-3.4	22.52	61	SSE
10^th	-2.5	21.41	32	SSE
10^th	-3.4	23.16	87	N
11^th	-3.3	22.05	62	SSE
11^th	-3.2	23.40	76	N
12^th	-3.3	22.30	86	N
13^th	-3.3	21.19	63	SSE
13^th	-3.2	22.54	76	N
14^th	-3.3	21.43	85	N
14^th	-3.4	23.18	89	S
15^th	-3.2	22.07	76	N
15^th	-3.2	23.42	55	SSW
16^th	-3.4	22.32	88	SSW
17^th	-3.1	21.21	77	N
17^th	-3.2	22.56	54	SSW
18^th	-3.3	21.45	87	S
18^th	-2.1	23.20	27	SSW
19^th	-3.0	22.09	53	SSW
20^th	-2.0	22.33	26	SSW
21^st	-2.9	21.22	52	SSW

Iridium Flares

The flares that I’ve listed are only the brightest, there are many more that are fainter, occur at lower altitudes and also after midnight. I’ve included one or two that do occur low down but to compensate they are quite bright. If you wish to see a complete list, go to www.heavens-above.com Times are all BST.

Jul	Time	Mag	Alt°	Az.
4^th	23.09	-7	26	NNE
5^th	21.29	-7	61	NE
9^th	22.49	-6	34	NE
14^th	22.28	-4	41	NE
19^th	23.30	-5	12	NNE
20^th	22.01	-8	51	NE
27^th	21.28	-3	60	ENE
27^th	23.02	-7	27	NE
28^th	22.57	-3	28	NE

Total Solar Eclipse

On July 22^nd there is a total eclipse of the Sun as seen from India, Bhutan and China. Sadly nothing is visible from the UK so we will have to watch via webcasts on the internet. Try looking on:-

http://www.live-eclipse.org or

http://exploratorium.edu/eclipse/2009/index.html

The NASA web site is also full of useful and interesting information at:-

http://eclipse.gsfc.nasa.gov/SEmono/TSE2009/TSE2009.html

Some Summer Constellations

At the June meeting I spoke about how to find some of the constellations in the Hercules area by starting off with the Plough and Boötes as earlier described in “Constellation Recognition No. 3”. It is then possible to locate Hercules, Ophiuchus and Scorpio. From these it is a simple task to find Libra and the two separate sections of Serpens. All four of the “Constellation Recognition” maps and instructions are available at meetings. Apologies for incorrectly spelling Ophiuchus on map no. 4, but the notes have it correctly.

Advance Warning for August

12/13^th August - Perseid maximum

Brian Mills

NASA SPACE PLACE

The Cool Chemistry of Alien Life

Alien life on distant worlds! What would it be like? For millennia people could only wonder, but now NASA’s Spitzer Space Telescope is producing some hard data. It turns out that life around certain kinds of stars would likely be very different from life as we know it.

Using Spitzer, astronomers have discovered the organic chemical acetylene in the planet-forming discs surrounding 17 M-dwarf stars. It’s the first time any chemical has been detected around one of these small, cool stars. However, scientists are more intrigued by what was not there: a chemical called hydrogen cyanide (HCN), an important building block for life as we know it.

“The fact that we do not detect hydrogen cyanide around cool stars suggests that that prebiotic chemistry may unfold differently on planets orbiting cool stars,” says Ilaria Pascucci, lead scientist for the Spitzer observations and an astrophysicist at Johns Hopkins University in Baltimore, Maryland.

That’s because HCN is the basic component for making adenine, one of the four information-carrying chemicals in DNA. All known life on Earth is based on DNA, but without adenine available, life in a dwarf-star solar system would have to make do without it. “You cannot make adenine in another way,” Pascucci explains. “You need hydrogen cyanide.”

M-dwarf and brown dwarf stars emit far less ultraviolet light than larger, hotter stars such as our sun. Pascucci thinks this difference could explain the lack of HCN around dwarf stars. For HCN to form, molecules of nitrogen must first be split into individual nitrogen atoms. But the triple bond holding molecular nitrogen together is very strong. High-energy ultraviolet photons can break this bond, but the lower-energy photons from M-dwarf stars cannot.

“Other nitrogen-bearing molecules are going to be affected by this same chemistry,” Pascucci says, possibly including the precursors to amino acids and thus proteins.

To search for HCN, Pascucci’s team looked at data from Spitzer, which observes the universe at infrared wavelengths. Planet-forming discs around M-dwarf stars have very faint infrared emissions, but Spitzer is sensitive enough to detect them.

HCN’s distinctive 14-micron emission band was absent in the infrared spectra of the M-dwarf stars, but Spitzer did detect HCN in the spectra of 44 hotter, sun-like stars.

Infrared astronomy will be a powerful tool for studying other prebiotic chemicals in planet-forming discs, says Pascucci, and the Spitzer Space Telescope is at the forefront of the field. Spitzer can’t yet draw us a picture of alien life forms, but it’s beginning to tell us what they could—and could not—be made of. “That’s pretty wonderful, too,” says Pascucci.

For news of other discoveries based on Spitzer data, visit:

www.spitzer.caltech.edu

Kids can learn Spitzer astronomy words and concepts by playing the Spitzer “Sign Here!” game at :

spaceplace.nasa.gov/en/kids/spitzer/signs.

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

CONTACTS

Chairman John Vale-Taylor

pjvalet1@tiscali.co.uk

Treasurer Mike Wyles 01892 542863

mike31@madasafish.com

Editor Geoff Rathbone 01959 524727

geoff@rathbone007.fsnet.co.uk

Events Phil Berry 01892 783544

phil.berry@tiscali.co.uk

Director of Observations Brian Mills 01732 832691

Brian@wkrcc.co.uk

Wadhurst Astronomical Society website:

www.wadhurst.info/was/

SAGAS web-site www.sagasonline.org.uk

Any material for inclusion in the August 2009 Newsletter should be with the Editor by 28th July 2009