[time-nuts] zero crossing of venus

Jim Lux jimlux at earthlink.net
Wed Jun 6 00:27:20 UTC 2012


On 6/5/12 5:20 PM, Tom Van Baak wrote:
> 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
>

or do something like compare the "centroid" of venus to "centroid + 
radius" of sun (or segment thereof.. )


it's pretty easy to get 0.1 pixel centroid precision, from what the star 
tracker, tiny moon finder folks tell me.





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