CalSky has an alert facility and can send daily emails about supernovae, lunar occultations, spacecraft passes and comets. Once of the options if to receive alerts when a satellite or spacecraft crosses the Sun or Moon. July has offered two opportunities to use the crossing alerts to capture some interesting images.

The first came on 5th July when the site predicted a possible occultation of 0.8 magnitude Altair by the International Space Station at magnitude -3.4. Most of the day had been overcast and it was only at 10pm that I decided to go out and watch the event at 22:16:35. On impulse I grabbed a Canon camcorder, put it on a tripod and zoomed in on Altair. With no time to adjust the settings I was surprised that I could get an image of Altair from the twilight and then it was a matter of a few minutes to wait for the ISS and start recording.

The video shows that this was a close pass and not an occultation but I was impressed that video camera was able to capture the event so easily.

The second alert came on 19th July when CalSky predicted that the ISS would cross the disk of Sun. So far this year, I have set up my ETX125 with a solar filter to capture an ISS Sun crossing twice earlier in the year. On the first I was not accurate enough on my timing and did not get any images; on the second cloud rolled in at the last minute. But this time weather conditions were perfect, I was working from home and determined to get the timing right.  

The ETX was tracking the Sun 30 minutes before the event and I had my Canon 350 DSLR on a sports setting to capture multiple images as quickly as possible using a home-built shutter switch. On a quick test I found I could capture about 10 seconds worth of images before writing to the memory card became a problem. Ten seconds gave me about 3 frames per second and so I decided to start firing images 5 seconds before the predicted time. Although I could not see the ISS through the rapidly firing shutter, there were two frames that showed the ISS moving from 4 to 10 o’clock (if the Sun were a clock face).

This approach worked but the sports mode I used gave me no control over the shutter speed or ISO rating. The automatic settings gave an exposure of 1/125 seconds which produced some motion blur, as seen in this scaled up image.

The blurring should not have been a surprise because according to CalSky the angular velocity of the ISS was 56.7′/s and the whole event took place in 0.6 seconds. Next time, I will use a webcam or video camera to try and record the event.

Pointing a telescope or binoculars at the Sun can destroy your eyesight or a digital camera chip. I am very grateful to Society member Chris Thayer for the long term loan of the ETX solar filter which makes my telescope safe for solar viewing.

Saturday 10th July

Farnham Astronomical Society was well represented at Fleet carnival on this blisteringly hot Saturday afternoon. We had several scopes on show and plenty of members images on our growing collection of display boards.  There was a steady flow of visitors and once the carnival procession arrived we were swamped with interested visitors both old and young. The society’s gazebo was a very welcome refuge from the Sun for visitors and the FAS team alike.

Some of our younger visitors were very taken with Kevin’s complete set of inflatable planets. After some debate about dwarf planets, Pluto was not put on display and had to be let down gently!

However, some of us want Pluto reinstated and are even wondering when Kevin is going to add inflatable moons, especially for Jupiter which is obviously missing it’s 63 companions! There was also speculation about an inflatable asteroid belt, comets and maybe a few thousand inflatable satellites around Earth…….someone’s going to be out of breath if we get them all :-) Jokes were also made about the re-creation of the inflationary period of the early universe, and the risk of a big bang!

This was also a chance to take our PST out on the road and meet the public on its first outreach event. We were lucky with the clouds and the PST was in almost constant use, although later in the day the polar alignment and setting Sun meant we had to kneel down to get to the eyepiece!

The Sun remains relatively quiet but we were able to show visitors to the carnival the solar disk and a prominance that appeared to be a loop of plasma projected from the solar limb. This larger than Earth-sized structure has already been nicknamed the “Fleet Prom.” 

Sunday 11th July

We were back at Fleet on Sunday to meet visitors to the dog and car show and were providing our audience with a great alternative to the Silverstone Grand Prix and the build up to the World Cup final!  The dog show (organised by Kelly’s Canines) and the car show at The Views brought a different, but no less family-oriented audience.  By noon we had signed up several new members.

There was a steady stream of interested folk and despite the odd large cloud there was much interest in the PST - which was very gratifying.

Kevin’s “Ask an Astronomer” challenge evoked a wide range of questions from the basic “If the Earth is spinning, why aren’t the stars and planets zipping past?” through the commonplace “What happened before the Big Bang?”, and “What is the Universe Expanding into?” to the somewhat challenging ”Can you explain quantum theory in layman’s terms?”. Answering each of these was “fun”.

Was it worthwhile for the Society?

Definitely!

The event has taken a lot of planning, preparation and hard work, but as usual it was great fun to be out there talking to the public about astronomy. We met all of our objectives – to raise awareness of the society; to sign up some new members, and of course to increase the public’s appreciation and understanding of astronomy – which is one of the goals of the society.  We also have many promises from potential new members who may come along to future meetings. If there is one important lesson for the society, it is that the public just do not know that we are ‘in town’ and so raising awareness and good publicity for the society is vital.

Also, we raised more money for the Carnival on the Saturday than any other exhibitor.

Acknowledgements

 Thanks to all of those involved for their hard work and contributions including:

• Danny Thomas
• Kevin Pretorius
• John Price
• John Rees
• John Moore
• Maurice Kent
• Peter Campbell-Burns
• Richard Kacerek
• Katherine Rusbridge

Our thanks also to Scopes’n'Skies for supporting us with their contribution to the PST.

A sunspot was clearly visible close to the limb surrounded by a brighter region of H-alpha. At the same point on the limb there were a number of promenances very close together.

I tried to image the features using a Celestron 2x Barlow plus an Astro Engineering Imagemate 1.6x magnifier attached to a Canon DSLR. I took a series of exposures at 1/160 second but was unable to bring out the sunspot although the prominences were clear.

I’m not sure if the focus, the tuning of the filter or the exposure was the cause of the problem but the cloud thickened preventing further investigation.

The purchase of the PST was supported by Scopes n Skies but now we have the scope it would be nice to purchase some clear skies!

In the evening Astronomical twilight begins when the sun sinks below the horizon and finishes when the Sun is 18 degrees below the horizon. Likewise, in the morning, twilight begins when the sun is 18 degrees below the horizon and ends at sun rise. These times  are important to astronomers as the twilight sky is not generally dark enough to observe faint objects like Comet C/2009 R1 McNaught which has been present in the early morning Northern skies.  Here in the UK and North of latitude 50 degrees, astronomical twilight lasts all night during midsummer.

Not that  I want to wish the Summer months away! Sunday 27 June 2010 was a fantastic day for lazing around in the Sun, even if England’s departure from the World Cup was a bit of disappointment.

The weather was so nice that I was still sat outside after 10 pm, looking up at the sky and thinking there was little of interest to observe. Arcturus looked brighter and more red than normal, as seen against the light blue of the western sky. The Summer Triangle of Vega, Deneb and Altair had emerged from the twilight putting the limiting magnitude around 2.5 or possibly 3.

However, I was proved wrong about the lack of interesting objects. About 10:26 BST, a bright meteor streaked across the Southern sky leaving a glowing ionisation trail in its path. The radiant appeared to be just below Vega and the end was somewhere in Virgo, towards the horizon.

Although the Moon had not risen sufficiently to have an effect on the ambient light, the twilight made estimating the brightness of the meteor difficult. However, my best estimate is around magnitude -3 or -4 which puts this into the fireball category as used by the Society for Popular Astronomy (SPA).

 This is the time of year for the “June Boötids” an annual shower that occurs when the Earth crosses the orbit of Comet 7P/Pons-Winnecke. This is a short-period comet that orbits the Sun once every 6.37 years.  This is not one of the most spectacular showers with hourly rates of 1 or 2 meteors, although recent unexpected outbursts in 1998 and 2004 saw 50-100 over the course of one night. The SPA quotes the dates of the June Boötids as June 22 to Jul 2 with the peak occurring on the night of June 23 to 24. They also note that in 1998 a further possible maximum was observed on June 27. Other sources (like Wikipedia) quote the dates as June 26 to Jul 2 with the peak occurring on the night of June 27. However, all sources agree on the unpredictable nature of this shower and the fact that most June Boötids are slow moving meteors.

 The radiant and speed of the meteor I observed, suggest that it was a background meteor which did not originate from the June Boötids. I have submitted a report to the SPA and it will be interesting to see if my sighting is verified by other observer’s reports. I hope they can confirm that it truly was a fireball class meteor and whether it could have been a June Boötid.

The instructions were straightforward and the PST worked out of the box with very little adjustment needed to get a clear image of the Sun’s disk. The most frustrating part was the clouds which were slow moving with tantalising gaps which just allowed some time to observe and take some images. The PST has a clever built in alignment tool called the Sol Rangefinder that allows the telescope to be aimed at the Sun. After finding focus with the 12mm eyepiece that ships with the PST, out came the 2x Barlow to step up the magnification. It was easy to bring the Sun into focus as a sharp disk and with a small adjustment of the separate tuning ring on the PST barrel it was possible to see fine details such as sunspots and prominances. 

This picture was taken with a Canon 350 DSLR using a 1.25″ nosepiece and the lens from a Celestron 2x Barlow. It is quite easy to spot the prominances between 6 and 9 o’clock on the clock and these were useful for checking focus.

Using a Canon 350 EOS DSLR exposures of around 1/60 or 1/80 second at ISO800 were enough to capture the filaments but tended to over-expose the fine detail of the sunspots at 11 o’clock on the disk. Sunspots  appear as dark spots surrounded by lighter areas and were distinct on the visual image. There are artifacts in the image that I think result from thin cloud that gives the impression of surface details in the top right quadrant.

The two features mentioned above are expanded in the images below. The Sunspots are not so distinct but there is a lighter “S-shaped” structure attached to the darker spot.

It struck me that although these features look small in the eyepiece, they are planet-sized structures so I added a scale image of the Earth to give a sense of scale.

It takes some time to tune the eye into the features of the solar disk in H-Alpha, but for a first observing session I was well pleased with the experience and pleasantly surprised to capture these images so simply and easily.

Society member Eric Grieve opened up the dome to the afternoon sunshine and talked through the operation of the telescope with members and their guests.

The telescope was positioned to project the Sun safely onto a sheet of cupboard.

Considering the age of the optics, the image of the Sun was relatively clear but there were no sun spots to enjoy!

Despite the fact that the telescope is over 100 years old, the clockwork drive was still able to track the movement of the Sun across the afternoon sky.

Thanks to Adam Thomas for taking the photographs.

The sunset from Lightwater country park was not that spectacular, but the view from Curley Hill did yield a surprise view of Venus and the New Moon emerging from the sunset. 

In this picture Venus is top left and bottom right is the Moon at 1 day and 7 hours old and only 2% of full.

Some credits……

I need to thank my Wife, whose sharp eyes picked out the Moon in the first place, otherwise I would not have stopped so long.

and I want to thank Tony who was also on Curley Hill for the sunset and who was kind enough to lend me the use of his tripod and lens for this shot. Having just gone out to photograph the setting Sun, I was totally unprepared for any astrophotography, so it was lucky for me that we met!

 (all times Local Time)

Interesting news on the BBC website regarding the installation of new lighting in Surrey.

It’s good news for Astronomers in that the new lights are directional and will be dimmed. Bad news is that the illumination cannot be blocked by filters.

But it’s good to see a council balancing the needs for safety, lower energy costs and actively reducing light pollution.

The light that goes up into space is not just spoiling the view, it’s a waste of energy !

Astronomers face a number of factors that can influence our view or image of the stars and planets even in a “clear” sky. Some of them are natural effects, like clouds or the light from a bright Moon. Moisture in the atmosphere can also play a big part and is the reason why the stars “twinkle” in the sky. Of course the effect is worse for objects that are close to the horizon and Astronomers use the word “seeing” to describe the quality of the view.

Then we have man-made effects – the most obvious being light pollution which is always the subject of much discussion in the Astronomy community. To an extent light pollution can be avoided by moving to a dark site or removed using specially designed filters at the eyepiece or camera. However, one effect which is harder to control comes from aircraft traffic which gets worse close to any major airport. The condensation trails from aircraft spread out at high altitude and can affect the seeing much the same as clouds. But also the aircraft themselves can cross the field of view and ruin an image. Particularly when taking wide-field pictures at night when the navigation lights appear as a series of parallel dots.

But occasionally you get an interesting image of a aircraft, like this one captured against the Sun using a Canon EOS450 camera at prime focus of an ETX125. The telescope was used in conjunction with a solar filter kindly lent to me by club member Chris Thayer. This picture shows both the aircraft and the vapour trails. Top right there are even two sunspots which were the real reason for the image in the first place!

It goes without saying that pointing any telescope, no matter how small, at the Sun can cause irrevocable damage to the eye and must not be attempted without specialist equipment and guidance.

Over Christmas I failed to get a similar picture of Santa with his sleigh and reindeer.  I was interested to see how Rudolph’s nose would look on a long exposure and curious as to whether reindeer leave a vapour trail………but there’s always next year!