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.

(all times BST)

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.

(all times BST)

Through one of its small and rather dirty window we had a restricted view of the observatory’s dark interior. Inside I could see a large refractor which was sitting on a huge equatorial mount. The mount appeared to be a very solid piece of engineering. Other items inside the observatory hinted at recent use. There were no signs of neglect and the interior was very tidy.  There were pictures on the walls, a slide projector for presentations.  I was able to take a photo through the window but it was near impossible to get a decent picture. My best shot is below. Written on a small slip of paper attached to the inside of the window pane was fixed a name and contact telephone number – presumably access could be arranged but we were already on the last day of our stay. I noted the contact details on the back of a shopping receipt which I subsequently lost (darn!).       

A plaque mounted on the wall next to the entrance identified the observatory as “Museo Astronomico Henry Tiarks”. 

So who was Henry Tiarks?  On returning to our hotel I paid my 1 Euro for 20 minutes of Internet Access. A Google search for “observatory marbella” returned nothing immediately useful (perhaps if I had some Spanish I could pick some better search terms). A search for “Henry Tiarks” however was much more fruitful.   This is just a small taste of what I discovered (Source: J. Brit. Astron. Assoc., 106, 4, 1996, Article by R. Elizabeth Griffin):      

Henry Tiarks was born in 1900 into one of the City of London’s merchant banking dynasties. His grandfather (after whom he was named) became a partner of Schroders and his father, Frank, was a director of the Bank of England from 1912. He had been introduced to the Astronomer Royal by his grandmother, and having seen Halley’s Comet as an 11-year old boy he was determined to see it on its next return, and did so in 1986. In retirement Henry lived in Marbella where he enjoyed his love of astronomy. He was the longest living member of the Royal Astronomical Society, having been admitted in 1916. He became acquainted with Edwin P. Hubble, and was invited as a personal guest to spend a night with him at the Mount Wilson 100-inch telescope. An obituary published by the BAA states that had telescopes mounted on both south and north balconies, while his 8-inch Cooke refractor in the garden was housed in a replica of the Palomar 200-inch dome. Henry died in July 1995.      

Is this the very same telescope and dome in Parque de la Constitucion? Apart from the dome being green (which must turn the observatory into an oven in the sumnmer sun) the shutter mounting shows a resemblance to the Mt Palomar dome.  I am no expert on old refractors but the mount is identical to other examples of telescope made by Cooke such as the 5″ Cooke refractor owned by the Hampsire Astronomical Group and 10″ Cooke refractor at the Mills Observatory in Dundee, Scotland.  I can find no information on the Internet to indicate whether the telescope and observatory was relocated to its current location – or perhaps the Park was once part of Henry’s garden.  If you should holiday in Marbella the observatory is worth a visit especially if you can arrange for someone to open it. The park entrance is located on Ave de Espana and is just five minutes walk from the promenade.  The sky above Marbella suffers badly from light pollution; with a three quarter moon I could make out just one solitary star. This is not a great location for an observatory but even a daytime visit just to see the Cooke telescope would be worthwhile.      

A view of the park and the observatory can be found on Google maps (the observatory is highlighted by the green arrow).       

M64 lies in the constellation of constellation Coma .  M64 was discovered by Edward Pigott 1779 and just days before Johann Elert Bode found it. A year later it was ‘re-discovered’ and catalogued by Charles Messier .  It is an unusual galaxy in that the inner and outer regions fo the disk appear to be rotating in opposite directions. This may be as a result of a galaxy merger.   The galaxy lies at a distance of approximayely 24Mly. 

M64 Imaged by John Moore – Click to enlarge

Imaged using a C11 on a G11 mount, ST10XME/CFW10/AO8. 

Exposure details: 

• L=13 x 600secs
• R=11 x 180s 2×2
• G=13 x 240s,
• B=10 x 360s

(Total = 4.58hrs)

More of John’s work can be seen on this site and on his personal websites: 

• John Moore’s homepage
• John Moore and Donal McDonnel’s Tenerife website 

M65 (left) is a type Sa spiral galaxy, and M66 (right) is an Sb spiral.  Both galaxies are approximately 33Mly away and are separated by an estimated 200,000 light years.   The two galaxies are similar in size.  The western arm of M66  is warped with respect to the plane of the galaxy and this is thought to be as a result of a past encounter with another galaxy in the Leo Triplet, probably NGC3628.   As a result, Hamilton Arp included M66 in his Atlas of Perculiar Galaxies (M66 appears as entry 16, the entire group appears as entry 317).  It is thought that M66 lost many thousands of solar masses in this encounter.  

In 10×50 binoculars M65 and M66 can be seen as faint nebulous spots.  In a small telescope both M65 and M66 remain in the same field of view with M65 appearing elongated.   

M65 and M66 imaged by Chris Thayer

Imaged using an ED80 mounted on an LX200 and a Mead DSI3

The Sombrero Galaxy

The Sombrero Galaxy is also known as M104, although it was not actually discovered by Charles Messier.  Messier became aware of this galaxy after it was discovered by Pierre Mechain in 1781 and he added a hand written note about it in his final catalogue.  It was awarded Messier object status in the early 1920s.  M104 was observed by William Herschell who recorded the dark lane bisecting the galaxy; this observation was confirmed by his son John in 1833.  Once classified as a spiral galaxy, it is now thought to be transitional galaxy between a spiral and elliptical.   Although it lies in the constellation of Virgo it is thought to be  a foreground galaxy and not part of the Virgo cluster.  We see the Sombrero galaxy edge on.  From this  viewpoint the huge dust lain dominates the view as does its pronounced central bulge which accounts for more than a quater of the mass of the galaxy.  The Sombrero galaxy also possesses a large halo of globular clusters – with an estimated 2,000 globular clusters it is perhaps the largest halo of all known spiral galaxies.    It is visible in 10×50 binoculars shows as an faint elongated blob and resolves into an elongated nebula a small telescope - but to see the dust lane requires larger apertures.  

Sombrero Galaxy by Kevin Pretorius

M88

M88 is a spiral (Sc) galaxy in the constellation of Coma Berenices.  Discovered by Charles Messier in 1781.   M88 is a member of the Virgo galaxy cluster (it also forms the end of the Markarian galaxy chain which starts with M86).   A type 1A supernova discovered in M88 in 1999 allowed the distance to M88 to be refined to approximately 57.2 Mly.  In 10×50 binoculars M88 is just a faint tiny spot but will resolve into an oval in a small telescope  

M88 by Kevin Pretorius