[time-nuts] Sidereal time

[ralph at ralphsmith.org]

Hmm. This gives me an idea of what to do with my second Western Union
Self-Winding clock. I currently use a Soekris Net4501, modified in a
manner similar to John Ackerman's, driven by a Thunderbolt. I use one of
the GPIO pins to provide the hourly synchronization pulse to my clock. If
I adjust the pundulum appropriately and modify my little program, the
second clock can show sidereal time.

Ralph

> True. At the observatory where I worked in the 70s there was a very
> accurate pendulum clock with a contact that incremented the clocks in the
> domes every siderial second.
>
> -John
>
> =============
>
>
>
>
>> Before the advent of automated telescopes that can point to an object of
>> interest a
>> wall clock displaying local sidereal time was commonly used to help
>> point a telescope
>> using setting circles and the known coordinates of the (astronomical)
>> object of interest.
>>
>> Bruce
>>
>> Steve Rooke wrote:
>>> Hi Brian,
>>>
>>> I really love this group, it appeals to the technophile inside me and
>>> it's interesting to see the answers that are given.
>>>
>>> You should have know that posting to a nuts group would mean you would
>>> get lots of highly technical responses but frequently the questions
>>> posed are not answered as things go off in a tangent. Perhaps we
>>> should have asked you how accurately bang on the "sidereal second??"
>>> you wish this clock to be or perhaps you just wish it to tick over the
>>> sidereal time without some frame of reference?
>>>
>>> Sounds like an interesting idea, sorry but I cannot answer your
>>> questions conclusively but it looks sound to me. What you are doing is
>>> fitting a sidereal day into a wall clock day display by driving the
>>> clock with fast seconds so it's 24 hours is over in 23 hours 56
>>> minutes and 4.091 seconds. If that's what you want to do, it sounds
>>> great even though I'm not sure that a sidereal day is normally
>>> presented that way.
>>>
>>> 73,
>>> Steve
>>>
>>> 2010/1/15 Brian Kirby<kilodelta4foxmike at gmail.com>:
>>>
>>>> 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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>>>
>>>
>>>
>>
>>
>>
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