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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