[time-nuts] zero crossing of venus

[Tom Van Baak]

Attached are two snapshots of a NASA live feed -- an interesting reminder about the difficulty measuring timing signals with great precision.

When you look closely, the leading edge of the sun is rather ill-defined, not unlike many 1PPS pulses. I suppose with enough photos, modeling, and image processing one could pinpoint when the transit (zero crossing) really occurs to great precision. Does anyone know more details how this is done? Is the state-of-the-art at the millisecond level? microsecond? nanosecond?

Thanks,
/tvb
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