[time-nuts] Sidereal time

[Jean-Louis Oneto]

Hi,
Her we use the following Java applet, on a computer synchronized through 
NTP:
http://www.gb.nrao.edu/~jbrandt/jLSTclock/

Its precision is enoughy for our need (we're an astronomical observatory, by 
the way)
About the math, the basic relation is that there is one sidereal day more in 
a sidereal year than in a tropic year, which give something like 
365.25/366.25 * 86400.
If you take a better value than 365.25, (365.2475 correespnd to the 
Gregorian approximation, you will be closer to the value you quoted).
HTH,
Best regards,
Jean-Louis
----- Original Message ----- 
From: "Brian Kirby" <kilodelta4foxmike at gmail.com>
To: "precise time" <time-nuts at febo.com>
Sent: Friday, January 15, 2010 3:12 AM
Subject: [time-nuts] Sidereal time


>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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