The Steavenson Award
The June Sky
Mr Mobberley opened by presenting a fine selection of images of the annular solar eclipse of 2003 May 31, which had been visible at sunrise from the northern extremities of Scotland, as well as Greenland and Iceland. BAA member Andrew Sinclair had produced an animated map of the path of the partial and annular phases, showing clearly their relation to the day-night boundary. On the day of the eclipse, there had been partial cloud cover which had obscured the view of some, but many others had enjoyed glimpses of it through breaks in the cloud, or through thin haze.
The BAA's only clear images of annularity had come from Dave Thompson, based in Dornoch. Other observers scattered around the Scottish countryside had only managed to photograph the very deep partial phase at best, although Nick James' footage from Durness was noteworthy. Nigel Evans had attempted to photograph the event reflected across the English Channel from Felixstowe, but the weather had not been favourable. He had, however, managed to take a series of images between 3:55 and 4:30UT, towards the end of the partial phase, and including final contact.
Eddie Guscott had succeeded in photographing a water-reflection of the partially-eclipsed Sun from Burnham-on-Crouch. However, the speaker was curious to know whether any Association members had taken advantage of the low altitude of the eclipse to obtain images of the rising, partially eclipsed Sun. At the Australian sunset eclipse of 2002 December 4, the superb "dolphin-fin" images by Nigel Evans had been a sensation. Presently, the only similar images from the May eclipse which the speaker was aware of were those taken by Radu Corlan in Romania, of sunrise across the Black Sea.
Looking ahead, the next lunar eclipse would be November 8-9, with 24 minutes of totality starting at 01:06:16 UT. The brevity of the total phase arose because the Moon would only just skirt the edge of the umbra on this occasion. The UK was, however, close to the optimal longitude to observe from. The next solar eclipse would be total, and would take place virtually diametrically opposite to the recent Scottish annular event, with the path of totality entirely confined within the Antarctic subcontinent. The maximum duration of totality was 1 minute 57 seconds. It seemed unlikely that many Association members would be braving the Antarctic climate, but the speaker wished any observing parties well on their travels!
The astronomical world had been largely quiet over the past month, with little activity in the planetary or cometary scenes. The most readily viewable comet at the time of the meeting was C/2002 O7 (LINEAR), which was at a rather faint mag 12, and would plunge into western twilight in early July. Looking ahead, however, there were some exciting prospects for the coming year. 2P/Encke would return in the autumn, making closest approach to the Earth on 2003 November 17 at approx mag 7, before passing through Cygnus into Vulpecula, and reaching perihelion on December 29. Historically, 2P/Encke had had an interesting past, having been independently discovered by numerous individuals on various returns. The first recorded discovery was by Méchain during the 1786 return, who had spotted the comet in Aquarius. This initial discovery was confirmed by Charles Messier. At the 1795 return, Caroline Herschel rediscovered 2P/Encke, with confirmation by William Herschel. Following further unconnected sightings at the 1805 and 1818 returns, the discoveries were finally pieced together in 1821-3 by Olbers and Encke, whose predictions anticipated the 1822 return. Encke was the second confirmed periodic comet, preceded only by Halley, and its namesake was later appointed Director of the Berlin Observatory.
The 2003 return of 2P/Encke would undoubtedly be the greatest comet of the year, with particularly good prospects in view of the fine southern return in 1997. Furthermore, a few observers had claimed naked-eye observations of the 1980 return, and with a peak around mag 6 possible in late November, it was well worth a look, especially with the Moon out of the way at this return. Mr Mobberley speculated that a quarter-degree coma might be seen.
Two exciting comet prospects for 2004 were C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR), both presently at around mag 14-15. The former was currently a southern object, with UK sky-watchers getting their first glimpse around 2004 May 1. Remaining a northern object, it would reach maximum brightness in Cancer around May 15, and the speaker speculated that it might reach first magnitude. The latter was already in the northern sky, where it would remain until 2004 February, by which time it might have reached mag 4. It would go on to peak in the southern hemisphere in mid-May, and could potentially reach first magnitude there.
Mr Mobberley recommended two asteroids which would be at opposition in the coming months for observation: 7239 Mobberley and 4205 DavidHughes. The Association's supernovae hunters had had a quiet month, but elsewhere, Robert Evans had made a bright mag 13.2 discovery on June 12 in M74, designated 2003gd. Variable star observers were requested to watch RS Oph, which had been observed for over a century to outburst around every 18 years from its usual mag 11 to mag 5. Assuming this pattern continued, such an outburst was expected in the near future. A second variable star to watch was ρ Cas, which was a good binocular target. It had initially generated interest in 1946, when it faded unexpectedly from mag 5 to mag 6. In 2000, a small, slow, brightening had been observed, followed by a sharp fading to mag 5.5. Recently some further variability in its brightness had been detected, and it was unclear whether this was set to continue.
The speaker took the opportunity to recommend the Philips ToUcam webcam, which was readily available for as little as £55 in the UK, and had proven to produce superb astronomical images. The lens was easily unscrewable, and could be replaced with a telescope adaptor, available from BC&F for £24.99, although the speaker had a contact who sold an equivalent part for £11.50, and Mr Mobberley was happy to pass further details to members keen to set up such cameras. He had been very impressed with the eyepiece-quality images which it produced, and its ease of use.
Finally, Mr Mobberley closed with the "Summer 2003 Sky Notes Challenge", which was to image Deimos, the outermost of Mars' two moons, from the UK. At opposition, Deimos was typically around mag 12.8, with its orbit taking it a maximum of 61" from Mars. It was incredibly challenging to observe because of the proximity of the parent planet, and an occulting bar was highly recommended for both visual observers and photographers. The speaker recommended a minimum aperture size of 25cm, and suggested taking exposures of 10-30 seconds. For the even more adventurous, Phobos presented an even greater challenge, never straying further than 25" from Mars. In this case, at least a 35cm aperture would be required. Night-by-night information of the whereabouts of the moons were available online at http://space.jpl.nasa.gov/
Dr Richard McKim was then invited to conclude Sky Notes with a summary of the Association's programme for the summer's Martian apparition.