โ Scribed by Jay M. Pasachoff; Brant O. Nelson
No coin nor oath required. For personal study only.
We report accurate timing of second and third contacts made from videotape of the total solar eclipse of 23 November, 1984, observed in Papua New Guinea. The magnitude of the discrepancies between predicted and observed times indicates that the secular change in the size of the Sun reported by some observers is within the uncertainty.
We observed the 1984 total solar eclipse on 23 November from Hula, Papua New Guinea, longitude + 147~ ' _+ 0.01' and latitude -10~ ' + 0.01'. We recorded the phenomena surrounding totality with a Saticon camera affixed with a 48-ram lens, and recorded the images on VHS-E (Australian standard). WWVH time signals are recorded on the tape.
Second contact, defined as the disappearance of the last Baily's bead/diamond ring, was recorded through a metal-deposited filter and appeared to occur at 21h21m50.9 s + 0.2 S. The filter was removed 1.8 s later, at which time we can confirm that no trace of photosphere was visible. Third contact was determined by the first visibility of the post-totality diamond ring, recorded without any filter, and occurred at 21h22m44.9 S + 0.2 S, making the duration of totality 54.0 + 0.3 s. The central time was thus 21u22 m 17.9 s + 0.3 s. Repeated independent timings of the duration from the tape gave 53.9 + 0.2 s. Stopwatch timings of the interval between succeeding minutes gave 1 min 00.01 s + 0.05 s. Times given were measured with a stopwatch with respect to the tones marking the nearest minutes. Errors given are one standard deviation of repeated measurements with a stopwatch.
Systematic errors could make these times slightly longer, though apparently by less than 0.5 s. At second contact, there conceivably could have been continued fading of the diamond ring after the signal dropped below the level detectable through the ND 5 chromium-deposited filter; accordingly we report second contact as occurring at 21h21m51.8 s _+ 0.9 S. At third contact, no filter was used, and the diamond appears to brighten abruptly, but could conceivably have been growing in the brightening chromosphere.
The predictions in the table of showing local circumstances for Hula ( + 147 ~ -10 ~ 05.0'), without corrections for the shape of the limb, were 55.6 s with maximum eclipse occurring at 21h22m16.8 s. Calculations in the same Circular by David Herald indicate that the limb corrections for Hula would be + 2 s at
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