[time-nuts] Sidereal time

Bill S wls at jbpet.com
Fri Jan 15 20:00:41 UTC 2010


Brian,
Last I looked, the solar/sidereal ratio was in fact 1:1.00273790935 
though that was a  while back. I build "precision" pendulum clocks and 
in designing a clock that would beat seconds and tell mean time as well 
as sidereal time I used a gear train of  15/47x49/97x82/31/x87/37 as I 
remember, which gave me an error of approximately .0073 secs/year 
sidereal. I know it's a bit arcane for this group, but the accuracy 
isn't bad! Doing the equation of time is mechanically a bigger pia...
Bill S

Brian Kirby wrote:
> I would like to have an electronic clock to keep sidereal time.  I am 
> planning on using a HP 59309A, which can except an external clock of 
> 1/5/10 Mhz.
>
> According to Wikipedia sidereal time is 23 hours 56 minutes and 4.091 
> seconds - a total of 86,164.091 seconds
>
> So 86,400 seconds for a normal "atomic defined" day divided by 
> 86,164.091 = 1.002,737,903,89
>
> If I set the 59309A to 10 Mhz external clock and dial a synthesizer up 
> to 10.0273790, the unit should be able to keep sidereal time.
>
> Is my math and theory correct ?
>
> Brian - KD4FM
>
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