It started with trying to run two long case regulators on one brick wall. Although the wall is founded on bedrock they interfere with each other. As I want to study their performance I tuned one to sidereal time, now they are independent. I run a TBOLT and a LPRO to maintain a mean time clock for the clock analysis. I am hoping to get a chip from TVB to divide the TBOLT or rubidium 10MHz down to PPS at sidereal rate to observe the performance of the sidereal regulator. Now I want to be able to set the sidereal time standard so, if I lose power on my rubidium, I can reset it so the longterm record of the sidereal long case will have no phase jumps. Also it seemed like a good idea, and the more it seems difficult, the more it needs to be done. cheers, Neville Michie
On 16/06/2012, at 5:51 PM, Ken Duffill wrote: > Hi, > > First of all why would you want Sidereal Time to that level of precision? > > I know this is the time-nuts so 'because I can' is a perfectly acceptable > answer. > > These days Sidereal Time is only used to display to humans in a recognizable > format an old and outdated approximation to the current ITRF <-> ICRF > transformations that the professionals would use to find or track a celestial > object. > > See IERS (http://www.iers.org/IERS/EN/DataProducts/data.html) and SOFA > (http://www.iausofa.org/index.html) for the details and sample code in > FORTRAN and 'C' for these transformations. > > I suspect if you want microsecond accuracy you will have to use the SOFA > routines, and have access to the IERS EOP Data. > > Cheers > > Ken > > On 16/06/12 07:20, Chris Albertson wrote: >> On Fri, Jun 15, 2012 at 9:49 PM, Mark Sims<hol...@hotmail.com> wrote: >> >>> Lady Heather can do sidereal time. Specify either the LMST, LAST, GMST >>> or GAST time zone (for Local/Greenwich Mean/Apparent Sidereal Time). >> >> I think the question was how to get Sidereal time to the microsecond level. >> A computer display screen only gets refreshed roughly 60 to 100 times per >> second so a screen can be tens of milliseconds off. >> >> How is this done professionally. Basically they don't. What you do is >> record a UTC time code on a track parallel to the data. Or now that >> everything is digital, the time code is sampled and multiplexed with the >> data. Later the display software can convert the time to whatever format >> is desired. >> >> > > > _______________________________________________ > 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.
