[time-nuts] Sidereal time
jim at jimking.net
Fri Jan 15 20:20:30 UTC 2010
I'm not sure your friend needs the time at all. Telescope tracking
mounts have a periodic error due to non-perfect mechanical parts. The
usual way to remove this error is to "train" the mount by manually
guiding it through one or more periods, or - probably more common these
days - use an optical autoguider.
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.
> 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.
> 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
More information about the time-nuts