[time-nuts] Sidereal time

[Bruce Griffiths]

If you actually need the apparent local sidereal time then the 
corrections detailed at:

http://www.usno.navy.mil/USNO/astronomical-applications/astronomical-information-center/approx-sider-time

may be necessary.

Bruce

Brooke Clarke wrote:
> Hi Brian:
>
> Why?  Do you just want to see the sidereal time on a display or do you 
> need a digital output?
> The Spark Fun "serial enabled" displays use what's called a "back 
> pack" that has the PIC 16F88 uC and it's used to do serial data to LCD 
> parallel data can control lines.  I've made some clocks using that chip.
> http://www.prc68.com/I/PIC16F88.shtml
> http://www.prc68.com/I/PRC68COM.shtml#07092006
>
> A friend is setting up an observatory where the pointing accuracy of 
> the telescope mount is specified as " 7 arcseconds or less 
> peak-to-peak periodic error before correction". Much better after 
> correction.  That implies he needs to know what time it is within tens 
> of milliseconds.
> http://www.prc68.com/I/StellarTime.shtml#StrMov
> We looked into different ways to get the time into his computer to 
> that accuracy and NTP looks like it will fill the bill, so a GPS 
> receiver may not be required.
>
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
>
>
> 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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