|
A week’s holiday beginning in Port Elizabeth and ending at Wilderness on the Garden Route gave us an opportunity to include a visit to the private observatory of Albert Jansen in the Karoo village of Prince Albert, north of Oudtshoorn. We had driven that day from Port Elizabeth and had underestimated the time it would take for us to complete the journey. Between Oudtshoorn and Prince Albert we had opted for the longer tarred road through the spectacular Meiringspoort Pass with the road winding its way across 23 drifts along the bottom of an 18 km gorge with towering rock faces on both sides of the road.
We arrived in Prince Albert after dark and expected to be able to find our B & B without difficulty, as the village doesn’t have more than a dozen or so named streets, but had to ask at the local information centre which was still open and very welcoming.
We had earlier in the afternoon contacted our host who explained that she would be out at about the time of our anticipated arrival, but that she would leave the door unlocked and the key on the table! Such a pleasant surprise for us security conscious Jo'burg-ites.
We phoned Albert Jansen and told him we would be around soon after we had had a bite to eat.
Shortly after 8pm we were greeted by Albert at his home on the outskirts of the village. We were immediately struck by his infectious enthusiasm and considerable knowledge of astronomy. He was at one time director of the Leiden Planetarium in Holland and later a lecturer in astronomy at the Technical College in Amersfoort. Deciding to emigrate to South Africa fulfilled his life-long ambition to be able to enjoy the dark unpolluted skies of the Southern hemisphere with its myriad of deep sky splendours.
On our first night we were shown many objects beginning with a view of Jupiter and its Galilean satellites projected on a black and white monitor by a video camera attached to his LX200 GOTO telescope. This method of viewing is particularly helpful if there are several visitors as all can see at the same time and the image can be quickly zoomed in and out. The belts on the giant planet were readily visible but the great red spot (which shares the ten hour rotation period of the planet) was out of sight.
We also observed the triple star Beta Monocerotis: components 4.7 / 5.2 / 6.1 mag, separations 7.3" for the wide pair and 2.9" for the close one. All three are B2 main sequence stars with emission lines. Discovered in 1781 by W. Herschel who called it "one of the most beautiful sights in the heavens".
We were surprised to be joined by a former member of the Johannesburg Centre, Nigel Wakefield, from Bristol in the UK, out on a visit to SA.
We now turned our attention to Albert’s 16 inch Dobsonian and took turns observing the globular clusters in Centauri and 47 Tucanae. At 150x some individual stars could be resolved but we agreed that the more spectacular views were to be had at lower magnification as the full extent of the object could be seen at a glance. By this time the moon had set and the Milky Way was spread across the sky in all its splendour. The coal sack and the large Magellanic cloud were easily seen as naked eye objects.
On our second night we started by exploring the Orion constellation and marvelled again at the Great Nebula M42 in the sword with the Trapezium showing prominently in the centre surrounded by a distinctly greenish nebulosity provided by the great light gathering power of the 16inch Dobsonian. The images were rock steady as the telescope was tracking in R.A. with the aid of a home-made Poncet mounting. Albert pointed out that this telescope gave one the satisfaction of hands-on astronomy as one could bodily shift the telescope with two hands to the desired direction. This evening we marvelled at Herschel’s Jewel Box NGC 4755 in Crux with its distinctly coloured stars. The Eta?Carinae Nebula revealed its dusty lane.
We marvelled that the second magnitude star Delta Velorum in the false cross asterism had escaped knowledge of its variability until as recently as 1997 when an observer in Buenos Aires had noticed a 0.3 magnitude dip. Subsequent observations, including those done by Albert, contributed to our knowledge that this star is an eclipsing binary with a period of 45.15 days and a half magnitude dip in brightness of only a few hours.
As Orion set and the constellation Scorpius rose higher in the sky we were treated to splendid views of M6 (the Butterfly Cluster) and M7 as well as the Open Cluster NGC 3532 in Carina now listed in the Caldwell catalogue of deep sky delights of Patrick Moore as No. 91
On the morning of May 7th we again joined Albert at his observatory, this time for the transit of Mercury. Unfortunately we could not see either the first or second contacts as his location was too far west. Consequently the transit was already in progress as the sun climbed over the hills on the horizon.
|
The subsequent stages of the transit were photographed by Albert through his 4 inch solar telescope.
The planet Mercury only 12 arc seconds across was easily seen on my own 49 mm image of the sun. This was projected onto a screen about half a metre behind the eyepiece of a telephoto lens gleaned from an old 8 mm cine camera. The image of Mercury was sharp in comparison with the fuzzy edge of a prominent central sunspot.
We were not equipped to record any contact timing of Mercury but were reminded that the observations in the mid 19th century revealed timing anomalies as large as 40 seconds, which were ascribed to perturbations arising from a hitherto undiscovered planet (suggested name Vulcan) in an orbit even closer to the Sun than Mercury.
However, no such planet was ever discovered and it was not until Einstein’s General Theory of Relativity, which provided a refinement to basic Newtonian mechanics, that a solution to the problem was found.
We heartily recommend a visit to the Prince Albert Observatory: a worthwhile detour from any journey to Cape Town or the Garden Route.
Margaret & Graham Tremeer
