Cathie and Byron Soulsby

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Baily Bead Analysis

Using the new version 3.0 of David Herald's WINOccult, Cathie's observations given in Table 2 below, yielded some interesting data as shown in the image. Here the 10 beads produced a correction to the Sun in Right Ascension (dRA = -0.15), Declination (dDec = 0.06) and a change in radius (dR = -0.44) all in seconds of arc.

Location

The observing location was 0.25 km south of the Mount Horner West Road at the entrance to the Mount Horner Property mid-way between Table Top Road and Piggery Lane. The estimated location was at Longitude 115o04.25' E, -29o07.27' S at an elevation of 150 m. We were positioned just inside the inner southern limit to observe the maximum number of Baily's beads at the northern limb of the moon.

Cathie successfully recorded 28 Baily's beads from the projection telescope screen.

Instrumentation

The instrumentation consisted of three units all mounted on a single tripod. These were a Sony TR511E Handycam video recorder with X 36 optical magnification and 2 layers of aluminised mylar as a solar filter, a 40mm Unitron projection telescope with shaded screen, and a 400 X 2 mm telephoto lens with a UV filter and one layer of aluminised mylar solar filter with a Canon command back photographic camera. The slide film used for 31exposures was Fuji Velvia 50 ASA at f/6.3 and 1/1000 s.

Weather conditions

The site was dust free even though a very strong wind blew from the south-west throughout the eclipse. The sky was very clear without clouds for the complete eclipse. The temperature was around 30 C. To offset the effects of the strong wind the instrumentation was set up adjacent to the car (see my slide 32).

Results

A video recording was made throughout the eclipse starting at first contact, included parts of the eclipse to annularity and a complete coverage of annularity in an attemp to capture Baily's beads. Cathie observed the projection telescope screen and made an audio recording during the eclipse of the Baily's beads seen. The Canon camera was used to capture coloured slides from after first contact to just after the last bead seen. The tables list these observations. In Table 1 as recorded by video and in Table 2 as recorded on the audio tape. All times are given in UT taken from the pre-set Sony cam-recorder timing signal which was found to be 33 seconds fast when compared with a short wave timing signal after the event.

Video record

The abbreviations used before annularity are: BFL = bead forming left cusp (South), BFT = bead forming top (centre of arc) and BFR = bead forming right cusp (North), after annularity they are BFB = bead forming bottom cusp (North), BF Middle = bead forming at centre of arc and BFT = bead forming top cusp (South).

Note: From audio start to the timing check the audio interval was 11m 47.4s less register 00 at 3.45s = 11m 47s. This compares to the Sony timer of 7h 21m 47s to 7h 33m 24s or an interval of 11m 37s, therefore these audio timings are 10s FAST compared to the video. The times in UT then are 10s FAST less the Sony timer of 33s FAST, hence add 7h 21m 47s less 43s = 7h 21m 04s to the times to correct audio timings.

Conditions

Wind effected the instrumentation and hand guiding of the tripod was not ideal as adjustment in altitude was not smooth enough. The video image was kept toward the top-right to ensure that the sun's image was seen fully on the projection screen for the audio record. Collimation of all three instruments was carried out before the car trip of about 400 km to the site, some slight movement must have occurred during the travel.

Dust was not a problem as we were in a quiet traffic area up-wind of the entrance road to the Mount Horner property with the added benefit of shade of many tall trees while not actually observing.

Acknowledgements

Special thanks are due to William Lees, the Mount Horner Property Manager for his kind permission for us to set up in an ideal location. The assistance of Jim Blanksby and David Herald in the provision of survey maps of the area, and the advice from Ken Jordan concerning photographic film and exposure is acknowledged.