Hmm. This gives me an idea of what to do with my second Western Union Self-Winding clock. I currently use a Soekris Net4501, modified in a manner similar to John Ackerman's, driven by a Thunderbolt. I use one of the GPIO pins to provide the hourly synchronization pulse to my clock. If I adjust the pundulum appropriately and modify my little program, the second clock can show sidereal time.
Ralph > True. At the observatory where I worked in the 70s there was a very > accurate pendulum clock with a contact that incremented the clocks in the > domes every siderial second. > > -John > > ============= > > > > >> Before the advent of automated telescopes that can point to an object of >> interest a >> wall clock displaying local sidereal time was commonly used to help >> point a telescope >> using setting circles and the known coordinates of the (astronomical) >> object of interest. >> >> Bruce >> >> Steve Rooke wrote: >>> Hi Brian, >>> >>> I really love this group, it appeals to the technophile inside me and >>> it's interesting to see the answers that are given. >>> >>> You should have know that posting to a nuts group would mean you would >>> get lots of highly technical responses but frequently the questions >>> posed are not answered as things go off in a tangent. Perhaps we >>> should have asked you how accurately bang on the "sidereal second??" >>> you wish this clock to be or perhaps you just wish it to tick over the >>> sidereal time without some frame of reference? >>> >>> Sounds like an interesting idea, sorry but I cannot answer your >>> questions conclusively but it looks sound to me. What you are doing is >>> fitting a sidereal day into a wall clock day display by driving the >>> clock with fast seconds so it's 24 hours is over in 23 hours 56 >>> minutes and 4.091 seconds. If that's what you want to do, it sounds >>> great even though I'm not sure that a sidereal day is normally >>> presented that way. >>> >>> 73, >>> Steve >>> >>> 2010/1/15 Brian Kirby<[email protected]>: >>> >>>> 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 >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- [email protected] >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>>> >>>> >>> >>> >>> >> >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
