[time-nuts] Sidereal time

J. Forster jfor at quik.com
Fri Jan 15 20:33:12 UTC 2010

That's the point I was making earlier.

Most telescopes have a FOV of at least 15 arc-minutes. You only need to
get the guide stars into the field and go from there.

Also, a telescope's pointing can be off in BOTH RA and Dec. Dec has
nothing to do with siderial time.




- probably more common these
> days - use an optical autoguider.
> Jim
> On 1:59 PM, 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
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