[time-nuts] Sidereal time

[J. Forster]

The 59309A is a GPIB interfaced clock unit and can be set to a specific
time via the GPIB interface. It also puts out the time and date via the
GPIB.

So it can be set to a specific siderial time from an external UTC clock w/
the appropriate SW to compute Siderial Time from UTC.

-John

===================


> It is an interesting question, we are so used to WWV and GPS with
> regular time signals to synchronise clocks to mean solar time.
> One method is to get a pocket calculator to identify a time in the
> future when a siderial second nearly corresponds to a UTC second
> and use the PPS pulse from GPS to jam a preset time into the Siderial
> clock, (or start a halted clock with the correct time preset.
> How long you have to wait for corresponding seconds depends on how
> accurate you want it.
> cheers, Neville Michie
>
>
>
> On 15/01/2010, at 2:25 PM, Bruce Griffiths wrote:
>
>> 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
>>>
>> That just gives the rate.
>> How are you going to set the actual Sidereal time to better than
>> the 0.9s that can be deduced from UTC?
>>
>> Bruce
>>
>>
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