For several years, the Astronomical Society of Southern Africa (ASSA) and the Explorers Society of South Africa (ESSA) have enjoyed sporadic star parties together. The basic arrangement is that ESSA provides a venue and ASSA the telescopes, so that people from both groups can come together for an evening of socializing, braais and stargazing. This year, the West Rand Astronomy Club was also invited, but our chosen date clashed with one of their own events, ironically also an observing evening in Magaliesburg not far from our venue.
Simon Donally once again booked Bushtrails, conveniently not too far off the beaten (or rather, tarred) track. This venue sports camping, dormitory/bungalow, braai & ablution facilities - as well as a nice rugby field from which to observe. A line of trees forms a good windbreak, the neighbors kindly turned off their outside lights and there are no other direct lights in the vicinity. Whilst the area is not as dark as in decades past, due to the inexorable spread of development, it is vastly better than in the metropolis. The light domes from surrounding civilization are moderate. There is a good view to the Southern polar region. I put in an order for a cold front to pass to ensure good conditions, and the weather delivered. Although some would-be attendees were scared off by the low temperatures and widespread low cloud in the morning, this all cleared by the early afternoon and comfortable clear conditions were enjoyed by around 60 enthusiastic participants. Almost a dozen telescopes ranging from my diminutive 60mm Coronado solar telescope to a towering 20” found their way to site, as did a number of large binoculars conveniently mounted for stability. It was a good opportunity to compare the performance of a variety of instruments both commercial and home-made.
Thanks to Simon’s good communication, participants were very well behaved with respect to using minimum light - predominantly red LEDs, pointed to the ground – which maintained our dark adaptation. They ware also careful not to accidentally nudge the instruments off target. A few surprised individuals exclaimed to me that it is amazing how well one can see to walk around without lights, even without the benefit of the moon. I hope this revelation will enable them to enjoy the beauty of the night sky wherever they venture, and prompt more support in the fight against light pollution.
Proceedings commenced with some solar observation. I received 3 alerts on the day about violent activity on the Sun; through the Coronado the whole rim of the Sun appeared hairy, with at least a dozen spectacular prominences visible. On the surface, a lot of rice-grain texture, some plages, one very bright spot and a number of filaments were visible. The queue to see these seemed never ending, and my arm became quite tired from holding my hand up to shield viewers’ eyes from the direct sunlight. (Note to self: contrive a light shield to attach to the telescope.) A white light projection scope also allowed good views of the sunspots to groups of people.
As the Sun set, people were still trying to view it, even through a tree silhouetted on the horizon. The Moon, but a sliver and only a day old, was being hunted around the globe to signify the end of a religious season. None of us were able to spot it, though elsewhere in South Africa it was photographed. As night fell, Mars and Saturn appeared from the gloom - neatly arranged in a pretty triangle with the bright star Spica. Even casual observers will have noticed the trio dancing with the young Moon in the week to come. Attempts to spot the nearby comet to which we had been alerted just the day before were to no avail, though a couple of us were convinced that there was “something” in the field on the fringes of visibility when using the averted vision technique… if one bumped the scope gently. But maybe it was more a case of “averted imagination”. Saturn of course wowed everyone with its ring system, even through the smallest scopes. Mars was too far away for much detail to be visible, though the ruddy spot was clearly a disk. Later in the evening, a number of people were privileged to see Uranus through the larger telescopes, and were startled at the blue disk. One could imagine that it is similar to how the Earth would appear from Mars.
The delights of the southern deep sky were abundant. Nebulae commonly observed included the fabulous Eta Carina and the famous but ghostly Dumbell. A number of planetary nebulae lived up to their appellations. After the spectacle of the brilliant strongly-condensed Omega Centaurus and the more loosely arranged 47 Tuc globular clusters, people were still not disappointed by lesser globulars. Much fun was had as observers tried to decide what colour stars could be seen in the Jewelbox, whilst the gem-like beauty of larger open clusters sprinkled throughout the Milky Way held viewer’s attention even as others jostled for a peek.
Throughout the evening familiar voices seemed to migrate to ever-bulkier silhouettes as layers of clothing were donned. Although the temperature remained above freezing, the low levels of physical activity mandated this, and it was gratifying that people not only had heeded the advice to come prepared but stuck it out. Since there were more instruments than drivers, it was possible for some of the ESSA crowd to take up the challenge of learning how to drive a telescope and try to find objects of interest by themselves (albeit with some guidance). The range of sizes allowed everything from low-power wide-field views, to close-ups of the planet, double stars and other small objects.
Apart from moderately technical discussions on the nature of the objects being viewed, including why they zipped through the eyepiece field at varying rates, I enjoyed a particularly insightful question about perceived differences in image quality. This is ultimately due to image contrast, the difference between point and extended sources, and the effects of varying magnification by changing eyepieces. Some of us are at least as interested in optics as in the targets.
Green laser pointers, judiciously used to delineate portions of the sky during discussion, helped beginners to find their way around the constellations and indicated where various telescopic targets were to be found. There were numerous comments to the tune of “I must get one of those!” (no doubt at least in part due to the Star Wars appeal). However, it should be emphasized that these are potentially hazardous devices. (In fact, although they are readily available, it is legally required for both vendors and users to be licensed by the authorities and for the devices themselves to be registered.)
After midnight, as people started fading, packing up and retiring for the night, the sky once more became less transparent as a moisture-laden layer moved in. As the last man standing, I was tired but happy at another successful joint event. So many pleasant people echoed my own thoughts that we must definitely do it again, that there is no option but to repeat it. Driving home with stars still dancing in my eyes and warmed by the glow of camaraderie, I was already looking forward to next time. What a nice bunch of people. What a pleasant evening. My thanks to all who participated; I look forward to seeing you again, to continue our exploration of the universe. Special thanks to Simon and the ESA committee for organizing the venue, and to those who brought instruments. To those who didn’t make it, better luck next time.
To all who took photographs of the event, please share your pictures. A little note on your experience of the evening would be appreciated too for our various newsletters. And if you are attracted to astronomy but do not want to spend a fortune on optics, remember – you too can build a telescope to rival the commercial offerings.
--- Chris Stewart.