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Stargazey Pie May 2008

The May meeting of the Highland Astronomical Society had plenty to keep everyone interested. Whether they went along to hear about the amazing satellite that is the Hubble Space Telescope, to see the future JSL observatory at Culloden, or to hear about some of the activities and projects being planned for the Society in the future, there was something for everyone. To start it all off, Pat Williams read out the notices, as Secretary Eric Walker was unable to attend:

  • Moon-phase Postcards. Please can someone buy the last of the Moon-phase postcards so that we can stop having to announce them – until next year! They are very handy for telling what the phase of the moon will be on any date in 2008, and you can even send them to people (though not on the Moon) as they are postcards. Only a few left at just £1 each. Please contact Pat Escott.
  • Seeing Stars. ‘Naming the Starry Patterns’ was printed in the Friday 2nd May edition of the Inverness Courier. It’s about constellations and asterisms, and is by yours truly, Antony McEwan. It can now be read here too.
  • Next Meeting. June 3rd will see Dr John Eldridge of the University of Cambridge visiting the Society. He will speak about ‘Stars in their Death Throes’. This and all future meetings will take place at the Green House until further notice.
  • Vacancies. As Pauline has stepped down from the Committee, there is now a position to be filled. Actually there are two, as there is also a space for a junior representative too. If you would like to be considered then please apply to one of the remaining Committee members. Meanwhile, our thanks go out once again to Pauline, who has contributed so much to the Society.
  • 2009 HAS Calendar Astrophotography Competition. This year we will be holding a competition to select the astrophotographs for inclusion in the 2009 HAS calendar. The competition will be judged by HAS members and will feature some exciting prizes for the winners. Eric has kindly agreed to run a series of workshops for members interested in developing their photographic and image processing skills over the next few months. These are likely to be held in the new observatory at times suitable for participants and trainer. If you are interested in registering, please contact Eric.
  • Sub-groups. If you are interested in joining one of our BAA-style sub-groups please put your name on the lists by contacting John Gilmour or Eric Walker. John has suggested that the leaders of these groups think about planning some activities in time for August.
  • Food for thought. If you are interested in attending the Society’s first ever Christmas Dinner (or it may be a lunch) please also get in touch so that the organisers can start to think about possible venues.
  • New Observatory Update. The building is now almost complete and the telescope and dome etc will be installed on 29th/30th May. There is still some finishing off to do, and hopefully by the time you read this some more volunteers will have been on site to help out with this.
  • Grand Opening. The public opening of the Jim Savage Lowden observatory will take place on the Summer Solstice, Saturday 21st June 2008. There will be many events taking place to mark the day – more details soon! We are honoured that Astronomer Royal for Scotland, Prof. John Brown, will perform the opening for us. He has told us that he definitely wants to be at the opening as a gesture of his “support and admiration” for all the hard work that we have put into the observatory, and in overcoming the problems that faced us.
  • Public Event. To raise public awareness of the forthcoming big day, we will have an Open Day in the Eastgate Centre on Saturday 14th June to promote the new observatory.
  • Remember… 2009 is the International year of astronomy. As mentioned in last months notices, there will be many exciting events coming our way, including special activities planned to coincide with the Moonwatch week.
  • Freebies. Rhona Fraser brought along some variable star goodies. There were two different types of booklet available: the ‘Variable Star Supplement’ is available free of charge, and the ‘Variable Star Section Circular’ (although it’s actually rectangular), published by the BAA is £2.50, and includes all the latest observation reports and news to do with variable star observing. There were some of these excellent booklets still available at the end of the meeting, so if you are interested in obtaining one please contact Rhona directly.
  • Monthly Astronomical Events: Saturn - well placed, but will be getting low by end of month. Galaxy fields of Virgo and Leo: visible all month. Mars – NASA’s Polar lander “Phoenix” touches down on 25th May. Noctilucent Clouds – may be a bit early, but keep an eye open for them from end of month onwards.

Subscriptions

Arthur Milnes spoke to us about the financial commitments that we have now that the new observatory is finally becoming a reality. Naturally there will be running costs in maintaining a superb facility like the JSL observatory, and it would be irresponsible not to prepare in advance for those costs. This is something the Committee have discussed at length and it was decided to see how the members would react to an increase in the membership fee, from £20 to £25. After one or two questions from the members present, it was put to a show of hands. The result was that a huge majority was in favour, and so the yearly membership fee for an adult has been increased to £25. The other membership rates have also increased slightly, so that they stand as follows:

Full membership: £25.00
Family membership: £41.25
Junior membership (age 16 & under): £2.50
Unemployed/student (age 17 – 22): £7.50
Non-members (per meeting): £2.50

Membership fees for 2008/09 are now due. The new programmes are now complete too, and have been emailed to all members with email addresses listed. For those without email they will be posted out this week.

As always, if there are any questions or if you have any problems remaining a member with that increase in subscription fee, please speak to one of the Committee members about it rather than simply not rejoining as the last thing we want is to lose members.

Dark Skies Scotland

The Dark Skies Scotland organisation is looking for a representative from the Scottish astronomical clubs and societies. The idea is so that the Scottish clubs and Dark Skies Scotland can work better together, by means of a ‘steering group’. Bill Leslie has connections with DSS and has helped with many of their public events. Three nominations have already been made so far, and no further ones are possible at this time. If you would like to hear more about this, please contact Bill directly.

There will be a Dark Skies type event run by SIGMA on 24th/25th October at their observing/meeting site at the Birnie Village Hall. Bill would probably be a good contact for information about that too, or you could contacts one of the other SIGMA members via the link above.

The Main Event
'The Hubble Space Telescope' by Chris Stradling

Chris is a member of the ‘other’ local astronomical society, SIGMA. He is a relatively new member of the club, and is currently serving on the Committee. He also serves as a navigator in the RAF, though I presume that astronomy is no longer a direct part of that duty!

Chris opened his presentation with a brief explanation of who the original ‘Hubble’ was, and how the telescope actually came into being. Born Edwin Powell Hubble in 1889, Edwin had a varied early life. He excelled in sports, studied many subjects and served in the First World War before earning his PhD in 1917, and was the first astronomer to use the newly completed 200-inch Hale Telescope in 1948.

He studied galaxies, particularly their spectra, and was the first to realise that the ‘Andromeda Nebula’ as it was known, was actually another galaxy completely outside our own. His spectroscopic work revealed the fact that starlight is ‘shifted’ when it reaches us. Light from objects that are increasing in distance is redshifted, and light from objects approaching us is shifted towards the blue end of the spectrum. Eventually it was realised that the redshift increased proportionally with the distance of the object from the Earth, so it implied that the objects are accelerating away from us. The ultimate conclusion of this work was that the universe is expanding.

One of the tasks that the space telescope named after Hubble would help to carry out was to establish the ‘Hubble Constant’ (the rate of universal expansion) to a much more accurate value. It did this very well, allowing us to use the data so derived to place an age on the universe of 13 to 14 billion years; much more precise than the 10 to 20 billion years that was assumed before.

Something that most people who are aware of the HST will know was that when it was originally launched it didn’t work properly. Chris explained that after launch in 1990, its first images were badly affected by an optical defect known as spherical aberration. It was caused by the outer part of the mirror being polished too flat by a matter of only about 2.2 microns (about 0.0022mm)! This tiny imperfection in the mirror’s figure meant that the images were very fuzzy and lacked clarity. A disappointing result, as the main aim of launching a telescope into orbit was to improve the images given by ground-based telescopes, which are traditionally distorted by being underneath the blanket of Earth’s atmosphere.

Still, it had always been planned to have servicing trips to the HST, and the first one was brought forward to fix this nasty problem. The first repair mission was STS61, flown by the space shuttle Endeavor. As well as fitting a corrective optics package known as COSTAR, it was intended that the crew would also replace two sets of faulty gyroscopes, replace the Wide Field/Planetary Camera system with an updated model, and replace the solar arrays. All tasks were accomplished, and thus began a long-running series of missions to update and repair the telescope, keeping it operational for fifteen years since the first wave of upgrades; eighteen years since launch – and counting!

During the presentation, Chris showed that he had researched every aspect of the HST very thoroughly. From the numerous committees that discussed the planning and construction of the project, to the various eminent astronomers and scientists who originally dreamed up the idea of a telescope that would orbit beyond the murk of Earth’s insulating blanket of atmosphere. Those inspirations went right back to 1923 and a German scientist, Hermann Oberth - one of the founding fathers of rocketry. In 1946 Lyman Spitzer Jr., an American astrophysicist, developed his ideas of an orbiting telescope, and spent the next fifty years working towards that goal.

The launch of Hubble would have taken place earlier, in 1986, had it not been for the Challenger disaster. Shuttle flights were halted and Hubble had to wait four more years before becoming an orbiting reality.

There cannot be many people around who have not at one time or another marvelled at some particular image that Hubble has produced. It has certainly captured the public’s imagination more than any other space mission since the Apollo Moon landings, and it has contributed so much to our understanding of the universe.

Basically, space telescopes are all about images and data gathering. Chris made sure we had plenty of images to marvel at, including some short movie files that showed many stunning (and world-famous) images. One of the movie files (which Chris said was the best he’d ever seen) combined hundreds of the images into a very short space of time, flashing on and off with upbeat music in the background. Although not to my taste, the fact that so many images (no two the same) had even been taken was mind-boggling! Other movie files dealt with the production of one of Hubble’s most impressive results ever…

The Hubble Deep Field Image.

The Hubble Deep Field shows an area of sky outside our galaxy, covering an apparent area similar to a tennis ball at 100metres distance. The telescope was positioned so that it could concentrate on this one area of sky for about ten and a half days in 1995 – constantly! Once the data had all been gathered, converted and merged into one image, it showed that even that tiny little bit of sky (about one two millionth of the total sky area) contained nearly three thousand galaxies! When the image first became public the scientific world was staggered. Similar observations have been carried out since then with similar results. They show that the universe is largely uniform over its vast scale, and that the area of space where we live is about average in every way. Nice to be special, isn’t it?

Hubble has undergone five repair/upgrade missions so far, and another one is planned for 2008, although it has been postponed until probably late September or early October. It is thought that the telescope will be retired in 2013 and will probably remain in a slowly declining orbit until 2021, when it may be remotely crash-landed into the sea to prevent it from breaking up randomly in the atmosphere.

Chris listed all the upgrades that each individual mission applied to the telescope, and also spent some time describing how the telescope actually works. It is basically a large compound telescope, similar to a Cassegrain, with the focal plane situated behind the primary mirror. Light is directed onto the curved primary, which reflects it to a smaller secondary mirror opposite the primary. From the secondary the now narrower light path is directed through a gap in the centre of the primary to the focal plane, where the various optical cameras and instruments gather it in. From Hubble, the data is transmitted to relay satellites, and then to a ground station at White Sands, New Mexico. From there it is beamed to Goddard Space Flight Centre, and finally a small hop to the Space Telescope Science Institute at Baltimore, Maryland.

Chris’s talk was entertaining and informative, and it was fantastic to revisit some of Hubble’s greatest achievements – and to be talked through the methods that it used to obtain them. The HST is an amazing device, and there can be few astronomers who would not be thrilled by having such an in-depth analysis of what makes it tick and how it came to be.

Thanks Chris. We look forward to hearing a similar talk about the Webb Space Telescope, say in about twenty years…

Highland Skies – May 2008

Stargazing during May will require that observers endure either sleep-depravation or intense time-management if they want to see celestial objects against a truly dark sky background. It won’t get properly dark until 11pm up until the middle of the month, and thereafter even later. However, that is not to say that it isn’t worthwhile staying up that late!

As insomnia struck the other night and I wandered the garden at 2.30am, I was struck by the Summer Triangle shining high and bright in the East. Not only the principle stars of Deneb, Vega and Altair, but the whole constellations of Cygnus and Lyra were visible, although Aquila was too low to be seen in its entirety. So that means a large swathe of Milky Way is up and about in the early hours, and if Lyra is high and observable then Hercules is eminently so.

Home of bright globular clusters M13 and M92, the constellation is easily marked by its trapezoid-shaped ‘cornerstone’ asterism, above and to the right of Lyra’s brightest star, Vega. Both globulars are easily found in small telescopes, or even binoculars, and yield astounding detail in medium to large sized telescopes.

If you’re lucky enough to be out in the wilds and away from streetlights in the early hours then the Milky Way will probably be quite noticeable. Seeing its great star clouds and black rifts running through the long axis of Cygnus, against a truly dark sky, will be a great precursor to studying it properly in the autumn. That will be something to look forward to – unless you are serious enough to set up a telescope late at night in May to get an early eyeful.

As we now endure/suffer/enjoy more hours of daylight than darkness, it seems logical that we should think of studying our daytime celestial companion: the Sun. If using a telescope to study the Sun, there are three main ways of doing so safely. First is to attach a full-aperture solar filter to the telescope. They can be bought ready-made (£25 to £50 or so) or constructed from Baader Solar Film to enable safe viewing of the Sun’s disc. This is fairly cheap to do and very safe. DO NOT be tempted to use a solar filter that screws into the eyepiece – they are very dangerous.

The second method is to project the Sun’s image out through the telescope’s eyepiece onto a piece of card or a special screen. For this the telescope must not be filtered, but it is essential that nobody peer into the eyepiece while the telescope is pointing towards the Sun or blindness could occur! Best to cover or remove the finderscope while solar observing for the same reason. Additional cost = one piece of white cardboard or similar.

The third method is to use a Herschel Wedge. This is a diagonal-like device that is inserted into a refractor telescope before it is pointed at the Sun. The wedge diverts a large part of the Sun’s energy out through a gap that points away from the observer, and the remainder can be directly observed through the eyepiece. This provides a good high contrast image of the Sun, though it is also the most costly method, as the wedge costs nearly £200 compared with about £15 for a sheet of Baader AstroSolar Film.

All of the above methods will allow the observer to see granulation on the Sun’s disc as well as Sunspots. An even more dynamic way to observe the Sun is to invest in a hydrogen alpha telescope. These allow the observer to view the Sun in one very specific wavelength of light, and to see prominences of solar matter blasting out from the Sun’s limb. They also show active regions on the disc, filaments (prominences in profile against the disc) and many other features. Prices are dropping too, with a Coronado PST hydrogen alpha telescope being available for less than £400 brand new. (Can you tell I got one myself? ?)

So there is plenty to see during May, despite (or even because of) our inevitable slide into ‘summer’.


JSL Observatory Visit

After the tea break, it was possible to go up to the site of the new observatory at Culloden and look around. It was a fine, mild evening, and many members did go up to see what progress had been made. I made my way there, and found several ahead of me in the new car park area. They were looking at the very fine crescent Moon, just visible between wisps of hazy cloud, about 10 degrees above the north-western horizon. It was a beautiful sight, and some of us were trying to spot Mercury, which at that time should have been only about two degrees to the west (left) of the Moon, but unfortunately nobody had managed to spot it by the time I left at about 10pm.

To make up for that though, we had a great opportunity to have a look around the nearly completed observatory. Many volunteers have spent the last few weekends working on the observing station building, painting, cleaning, brushing, sticking and doing all the things required to make it a proper viable area. The construction looks very good, and the interior seems more spacious than I had imagined! Of course, there’s nothing in there yet…

From the raised platform where the dome and telescope will be located we spent a while Moon-watching, then jumped around on the gravel for a while to help it settle (yes, we really did)!

It is just so close now! Amazing to think that when the next real observing season starts we will have a fully operational state-of-the-art observatory to use! If you haven’t been up (either to help out or just to have a look) it’s well worth the trip.

If, like us, you didn’t manage to see Mercury alongside the Moon on Tuesday night, I attach Eric Walker’s excellent picture showing the conjunction here.

 

 

Next Time

The next Society meeting takes place on Tuesday 3rd June, 7.30pm, at the Green House. Dr. John Eldridge will be speaking about ‘Stars in their Death Throes’ so be sure to wear black. There will no doubt be more information about the progress on the new observatory (which should be fully equipped by then) and other activities being organised by the club. The irresistible twin lures of tea and biscuits will also be present.

In the meantime, enjoy the daytime and night-time skies, and feel free to visit our message board anytime.

Clear skies,

Antony McEwan

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