The theodolite is not a problem, I use a distant street lamp (4Km
away) as a referred object (RO) to set azimuth,
and with the usual levelling it takes moments to set the co-ordinates
of a chosen star.
The RO is observed by one of several methods to get a good azimuth.
It is chosen to be visible by day or night.
Then I listen to the clock ticks and watch the star cross the
graticule. The star co-ordinates are from an ephemeris.
You can repeat with the same star or others at later times.
I have not looked at the sidereal time on Lady Heather yet, I was
unaware of it.
cheers, Neville Michie
On 02/03/2012, at 10:14 PM, mike cook wrote:
Le 02/03/2012 05:13, Neville Michie a écrit :
A possible solution is to take mean time (from a TBolt 10MHz) and
divide it by 9,972,695.7 to give a PPS(sid) signal that can run a
digital clock dial and give one second(sid) ticks to phase the
pendulum. It may be simpler to divide by 9,972,696 to stay with
integer division and have an error in the order of a second per
annum. (which we have from leap seconds anyway).
TVB made some picDIV chips with a synch pin that do a similar
task, but have I got the number correct?
number looks ok , at least according to the usual sources.
and are there other nuts that would like to add a sidereal clock
to their clock vaults to make it worth while to make such a chip?
Yup, I guess that would be a useful extension to the code. You
would just need to change the delays to fit a 2493174 instruction
count for a 10MHz input.
If I set up the sidereal clock then I can use my theodolite to
check time against the stars.
More of a challenge I think. Harrison is reported to have used
occultation by buildings from a known observation point. It would
be probably be easier than keeping a theodolite precisely
orientated over long periods of time.
cheers,
Neville Michie
Sydney
Australia
_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/
listinfo/time-nuts
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/
time-nuts
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
