MEETINGS

 

      Not exactly a Meeting but on Saturday August 29th the Society will be having an Astro-barbecue as guests of Michael and Claire Harte!

 

        There is no meeting of the Society in August but Michael Harte and his wife Claire have again offered to host an Astro-barbecue at Greenman Farm!

         Members are invited to bring along telescopes, binoculars and anything else they think would be useful to see the night sky in late August.

        Any member of the Society and family is welcome to bring food to cook on a barbecue and drink, and then take advantage of the darkening skies to view the heavens that evening.

        You don’t have to bring a telescope; a number will be there anyway, so just bring yourselves and enjoy the company.

        Michael suggests that members aim to arrive about 1900.  Greenman Farm, Wadhurst, is on the south side of the road to Tunbridge Wells, the B2099, just to the west of the railway over-bridge.

        The entrance to the farm is through two huge gates and there is plenty of room inside for parking.

        One last note, Michael suggests bringing some warm clothes as it can get cold in the evenings at the end of August.

 

 

JULY MEETING

 

        Phil Berry introduced the meeting and reminded members that, although there is no meeting in August, Michael Harte has invited Society members to another Astro-barbecue as already referred to above.

        Phil also mentioned that a recent member-society to join SAGAS (The Southern Area Group of Astronomical Societies) is Ashford Astronomical Society.  They are holding an event on the 24th of October called “Astro Bash 2009 Star Party”.  Their Society meets at Woodchurch, about 5 miles south–west of Ashford.  There will be more details in the September Newsletter

        John Murrell, a member of Croydon Astronomical Society was introduced to members and Phil thanked him for stepping at fairly short notice to talk about something he had spoken to us about some 4 years ago.

 

Virtual Observatory 2009

 

        In May 2005, John Murrell told us about the huge amount of Astronomical data of many kinds held on sites all around the world and explained that the Virtual Observatory was in the course of preparation through which much of this data may one day be accessed by everyone.

        At this meeting, John told us how things had progressed and what data could now be reached in “Astronomy on the Internet”.

        First it was necessary to define amounts of data storage.  We are all familiar with Megabytes (a million bytes) and Gigabytes (1,000 Megabytes), but in the Virtual Observatory (VO) it is necessary to expand to Terabytes (1,000 Gbts), Petabytes (1,000 Tbts) and even Exabytes (1,000 Ptbs).  You would need ¼ million DVDs to store just 1 Petabyte!

        It is interesting to think that the US Library of Congress holds some 10s of Ptbs.

        Some of the astronomical data is from sources that are quite old but new data is being gathered at an increasing rate all the time.  John showed various methods used to gather modern data such as the Sloane Digital Sky Survey, the 2-micron All-Sky Survey and the Super Wasp Planet Hunter which consists of a number of CCD cameras and covers both north and south hemispheres continuously.

        The huge new Synaptic Survey Telescope will have an 8.4 metre primary f1.2 mirror with a 9.6 square degrees (3x3) wide field of view.  The 3.2 G-pixel CCD will take 15 second exposures (allowing images of objects down to magnitude 24.5!)  To scan the whole sky will need 1,000 images and this will complete this every 3 nights.

        The telescope will be sited in Chile and should be operating in about ten year’s time.

        Where does all this data go?  Onto the Virtual Observatory!

        John went on to say that the object of the VO is to make a vast amount of astronomical data seamlessly available from a worldwide network of servers via internet links and this enables investigations to use sources in many wavelengths.

        Material is being digitised from old original plates, data from very old catalogues and archives (which is expected to double every 2.5 years.  In fact John said that just searching 1.5 PB would take several months and the 2.3 million discs needed to store it would stack 2.8 Km high!

        Some of the older material is stored on formats that are no longer used such as the 8-inch floppy disc used in the mid ‘70s so has already had to be converted before being made available.

        Three principle applications are already in use.  They are Astro Grid Desktop, Aladin and NASA SkyView.

        John showed some of the images from Astro-Grid Desktop which can give access to multiple sources available for downloaded from:

http://astrogrid.org/

He showed how to access the site and download data and tables in Top Cat which is an interactive viewer for data in tabular form and written in Java.

        One versatile source he showed was the “Splat” spectral analysis of selected objects.

        SkyView is a virtual observatory generating images of any part of the sky at any wavelength from radio to gamma-rays.  One remarkable example showed the whole sky, first in radio waves then in extreme UV and finally in X-ray light for comparison.

        John then showed how one could find an image of M45 in one of many forms as an example.

        Aladin is an interactive sky atlas from the ‘CDS’ in Strasbourg.  We were shown how to access the image of a certain supernova and then by clicking on it, obtain further information about object.

        He demonstrated how a coloured image of M1 could be obtained from various stored sources, and then by clicking on the central pulsar more information became available.

        By using SINBAD (Set of Identification, Measurement and Bibiliography for Astronomical Data) more information can be overlaid as we were shown using M45 as an example.

        We then looked at many other examples using images and superimposing data in the form of overlays.

        Practical examples were talked about.  One such case was of Michael Oates, a keen amateur astronomer and computer wiz who has used the VO to amongst other things, search for comets and has already discovered more than 140 in SOHO data.  Sadly these comets cannot be named after the discoverer since they were not directly discovered.

        The Aladin portal can be found at:

http://aladin.u-strasbg.fr/aladin.gml

        Datascope is another vast source of data.

        It was also suggested that members might like to look at:

http://heasarc.gsfc.nasa.gov/cgi-bin/vo/datascope/init.pl

        For further information on amateur VO, John Murrell has a web page on:

www.johnMurrell.org.uk

        Before John closed his excellent talk he mentioned Google Sky, Microsoft’s Worldwide Telescope and Galaxy Zoo which has been referred to in a previous Newsletter.

 

 

FUTURE MEETINGS

 

        Meetings begin 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)

 

        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 21st 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 AUGUST

 

Planets

 

Mercury at magnitude +0.1 may possibly just be seen in the west immediately after sunset around the middle of the month. At best it sets around forty minutes after the Sun so the horizon and conditions will need to be perfect.

 

Venus is still a morning object at magnitude -3.9 rising three hours ahead of the Sun. It’s phase is gibbous at the moment although as the percentage of the planet we can see increases so it’s brightness will decrease along with it’s apparent size.

 

Mars at magnitude +1.0 lies on the Taurus/Gemini borders and is still just about a morning object rising a little before 01.00 BST by the middle of the month. It is however growing in apparent size, which will have doubled by the end of the year, and in brightness as it heads towards opposition on January 29th next year.

 

Jupiter at magnitude -2.8 still lies in the constellation of Capricornus and rises at the same time as the Sun is setting by the middle of the month. The planet comes to opposition on the 14th after which it will gradually decrease in magnitude and apparent size. On the night of the 3rd/4th August Jupiter occults the star 45 Capricorni. See below for timings.

Saturn is to all intents and purposes lost in the glare of twilight as it moves towards conjunction with the Sun on September 17th.

 

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. Times are BST.

 

Aug.

Time

Star

Mag.

Ph

PA °

3rd

22.02

SAO 187993

6.8

DD

97

26th

20.56

SAO 183513

6.0

DD

43

30th

20.06

SAO 187599

5.6

DD

54

30th

22.11

SAO 187660

7.3

DD

59

30th

23.49

SAO 187718

6.3

DD

104

 

Planetary Occultation

On August 3rd a rare event occurs when the planet Jupiter passes in front of (occults) the star 45 Capricorni. The star at magnitude +5.9 will be a relatively easy object and will appear at first glance to be another of the planet’s moons. However, at 22.55 BST Jupiter will occult the star and it will remain hidden for a little under two hours reappearing at 00.45 BST (August 4th).

 

Phases of the Moon for August

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

 

Full

Last ¼

New

First ¼

 

6th

13th

20th

27th

 

20.40

22.34

05.50

15.19

Rise

05.52

14.32

19.58

22.29

Set

 

Meteors

The night of August 12th/13th sees one of the years most active meteor showers reach maximum. The Perseids occur thanks to the trail of debris left by the comet Swift/Tuttle on it’s successive orbits around the Sun. When it’s orbit is crossed by the Earth we experience a period of increased activity with possibly one meteor per second being seen. If you follow the meteor trails backwards you will find that they all intersect at one point known as the radiant. The radiant for this shower lies in the constellation of Perseus - hence the name. The meteors produced by the Perseids are often very fast and bright and sometimes leave an ionised train behind them which lingers for a few seconds after the meteor itself has disappeared. Occasionally the meteor explodes in mid-flight. The best way to watch the Perseids is to lie in a lounger that is almost fully reclined (it is far too uncomfortable on the neck to observe whilst standing) and look in a north easterly direction. If possible choose a location where you can see as much sky as possible. The meteors can appear pretty much anywhere in the sky and not necessarily close to the radiant. There are suggestions that this year could see increased activity in comparison to previous years due to the proximity of the Earth to the debris trail left by the comet’s1610 return so it’s just possible we may see something special.

 

Eclipse

On the night of the 5th/6th August there is a penumbral eclipse of the Moon. This is where the Moon passes into just the penumbral shadow of the Earth and not into the darker central umbral area. Below is a diagram showing the different areas of shadow.

 

The diagram below shows the best times (in BST) to look for the penumbral shadow and where it will be. Please note that the defining line between the eclipsed and un-eclipsed areas will not be a sharp one.

 

 

 

ISS

Sadly, there are no passes of the ISS as seen from Wadhurst this month that occur before midnight. Details of all passes can be found at:

www.heavens-above.com

 

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. Those of us who visited the pub after the July meeting emerged (glass in hand) to watch a magnitude -2 Iridium flare that Phil had mentioned earlier in the evening, and sure enough, right on time, it appeared. This month there are quite a number of really bright flares.

 

Aug

Time

Mag

Alt°

Az.

1st

22.42

-7

34

NE

2nd

21.01

-6

69

ENE

2nd

22.36

-2

35

NE

3rd

20.55

-3

69

ENE

6th

22.21

-6

42

NE

7th

22.15

-3

42

NE

11th

23.15

-6

11

NNE

12th

21.54

-6

50

ENE

13th

21.48

-2

49

ENE

15th

23.01

-6

18

NNE

18th

21.27

-2

58

ENE

18th

22.52

-7

23

NE

19th

21.21

-6

57

ENE

19th

22.47

-3

24

NE

25th

20.54

-3

65

E

26th

20.48

-3

64

E

26th

22.23

-2

35

NE

27th

22.17

-7

34

NE

28th

22.11

-2

35

ENE

31st

22.03

-2

41

ENE

 

I think it may be worth explaining again that in simple terms an Iridium flare is caused by the Sun reflecting off of an antenna on one of the Iridium satellites.

In 1987 the Motorola company proposed the creation of a network of orbiting satellites to provide mobile phone communications. They designed the system to use 77 satellites - the atomic number of the metallic element Iridium. Due to cost cutting they redesigned it to only use 66 but kept the original name and by 1998 the network was ready. However it had cost around seven billion dollars to build and because the cost of calls was prohibitive there were very few subscribers, with the result that the system was switched off the following year. Fortunately the US Defence Department stepped in and saved the project so that today the Iridium satellites are still operating.

Each satellite has three large rectangular aluminium antennae which occasionally reflect the sunlight and cause the flares (up to magnitude -8) which can be predicted to a very high accuracy.

 

Brian Mills

 

NASA SPACE PLACE

 

SARSAT to the Rescue

 

        If a plane crashes in the woods and nobody hears it, does it make a sound?

        Never mind contemplating this scenario as a philosophical riddle. This can be a real life or death question. And the answer most of the time is that, even if no people are nearby, something is indeed listening high above.

        That something is a network of satellites orbiting about 450 miles overhead. The “sound” they hear isn’t the crash itself, but a distress signal from a radio beacon carried by many modern ships, aircraft, and even individual people venturing into remote wildernesses.

        In the last 25 years, more than 25,000 lives have been saved using the satellite response system called Search and Rescue Satellite-aided Tracking (SARSAT). So what are these life-saving superhero satellites?

        Why they are mild-mannered weather satellites.

        “These satellites do double duty,” says Mickey Fitzmaurice, a National Oceanic and Atmospheric Administration (NOAA) systems engineer for SARSAT. “Their primary purpose is to gather continuous weather data, of course. But while they’re up there, they might as well be listening for distress signals too.”

        In February, NASA launched the newest of these Polar-orbiting Operational Environmental Satellites (or POES) into orbit. This new satellite, called N-Prime at launch and now dubbed NOAA-19, prevents a gap in this satellite network as another, aging NOAA satellite reached the end of its operational life.

        “The launch of N-Prime was a big deal for us,” Fitzmaurice says. With N-Prime/NOAA-19 in place, there are now six satellites in this network. Amongst them, they pass over every place on Earth, on average, about once an hour.

        To pinpoint the location of an injured explorer, a sinking ship, or a downed plane, POES use the same Doppler effect that causes a car horn to sound higher-pitched when the car is moving toward you than it sounds after it passes by. 

        In a similar way, POES “hear” a higher frequency when they’re moving toward the source of the distress signal, and a lower frequency when they’ve already passed overhead. It takes only three distress-signal bursts — each about 50 seconds apart — to determine the source’s location.

        Complementing the POES are the Geostationary Operational Environmental Satellites (GOES), which, besides providing weather data, continuously monitor the Western Hemisphere for distress signals. Since their geostationary orbit leaves them motionless with respect to Earth below, there is no Doppler effect to pinpoint location. However, they do provide near instantaneous notification of distress signals. 

        In the future, the network will be expanded by putting receivers on new Global Positioning System (GPS) satellites, Fitzmaurice says. “We want to be able to locate you after just one burst.”  With GPS, GOES will also be able to provide the  location of the transmitter.

        Philosophers beware: SARSAT is making “silent crashes” a thing of the past.

Download a two-page summary of NOAA-19 at:

www.osd.noaa.gov/POES/NOAA-NP_Fact_Sheet.pdf.

        The Space Place gives kids a chance to rescue stranded skiers using their emergency rescue beacons. The Wild Weather Adventure game awaits them at;

spaceplace.nasa.gov/en/kids/goes/wwa.

 

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 September 2009 Newsletter should be with the Editor by 28th August 2009