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25 June 2004 Notes on the Transit of Venus: 8 June 2004 Paul Curtin
Preparation is a crucial element in any successful scientific endeavor. One often spends much more time on the design of an experiment than in actually making observations. This is especially true in documenting transient astronomical events, such as the transit of Venus on 8 June 2004. Most observers in North America would see less than two hours of the transit, even with excellent viewing conditions. Poor weather, unfortunate choice of site or misbehaving cameras could have further reduced the opportunity for useful observations. After assembling the necessary equipment, reviewing our event plan and brewing a very large amount of coffee, the only remaining worry was cloud cover. Fortunately the day of the transit was a shining exception to our otherwise rainy Spring. The following is a summary of the observations made by my wife Leslie and myself. Location In search of a horizon We investigated a number of potential observing sites. By far the best candidate was the Boston Hill Nursery in Colden, New York. This site is on the crest of a hill roughly 25 kilometers (around 15 miles) southeast of Buffalo (latitude 42 41'30"; longitude 78 43' 00"). The horizon is completely unobstructed and the region to the east is rural and relatively free from manmade pollution and thermal activity, though dust, mist and natural thermal effects are always concerns. The owner of Boston Hill, Brad Schottin, graciously permitted us to set up our equipment on the grounds of the nursery. We located a level spot close to the parking lot in order to facilitate setting up in the dark with a minimum of fumbling. Equipment and Setup As the transit was already well under way by the time of local sunrise (5:30 EDT), it was imperative that we get an early start. The fact that we would need to polar align the equatorial mounts of our two telescopes meant that Polaris had to be visible, so set up needed to both very early and rather dark. By 4:20 EDT, both telescopes had been assembled and polar aligned. The moon provided a perfect focus test, and the eyepiece mounts were locked. Clock drives were tested for 15 minutes. Once verified, they were turned off to conserve battery power. The 9 cm, f/11 refractor and 15 cm, f/8 reflector were both stopped down to 7cm, and the telescopes and finder scopes were equipped with Baader AstroSolar Density 5 filters. The photograph above suggests that I have a rather weak sense of equipment design aesthetics. But the overriding concern in the filter cell construction was eye safety. Therefore, all cells were made to resist strong gusts and unexpected jostling. The refractor was equipped with an 18-mm eyepiece and the reflector had a 26-mm Plossel. This gave us sufficient magnification while allowing for a fair view of most of the solar disk. Photographs were taken with a Minolta T201 (f/4, 1/500 second) and a Nikon FM10 (f/11, 1/60 second) using Kodak T-Max 100 film. Color shots were made using a Pentax 90 WR automatic using Kodak Goldmax 800. We synchronized a digital clock using shortwave time signals and read off timed observations into a handheld tape machine. Observers who wish to report event timings to central data collectors (e.g. for occultations or eclipses) should consider recording the entire observing session on audio tape with the radio time signal either prominently in the background or directly onto the second tape track. When doing this it is crucial that the tape machine is closely monitored. Observations Some of the photographs we made of the transit are shown below. Note that even a projected image of the Sun clearly shows the shadow of Venus.
Acknowledgments We thank Brad Schottin and Boston Hill Nursery for allowing us to make use of their property. Thanks are also due to Brighton-Eggert Animal Clinic, The Legal Aid Bureau of Buffalo and Daniel and Elaine Curtin, without whose support our small expedition would have been impossible.
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Copyright 2004 by Society for Amateur
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