Hal Murray wrote: >> I've been thinking of how to make a sidereal clock that's very >> accurate. Things like time of coincidence between sidereal and UTC0 or >> better UTC1 come up. There are very few sources for UTC1. >> > > How far out do you want to go on the time-nut scale? > > A radio astronomy friend says they get UT1-UTC from USNO. I haven't found > the page where it's published (yet), but I did find this one which has the > math for conversion to sidereal time: > http://aa.usno.navy.mil/faq/docs/GAST.php > (Which brings up an interesting tangle, since the USNO gets some of their > data from VLBI.) > > The wiki page on DUT1 (UT1-UTC) (http://en.wikipedia.org/wiki/DUT1) says: > Forecast values of DUT1 are published by IERS Bulletin A. > Weekly updated values of DUT1 with 0.1 s precision are > broadcast by several time signal services, including WWVB. > > So if 0.1 second is good enough, listen to WWVB. If you want better, try > this: > http://maia.usno.navy.mil/ser7/ser7.dat > which starts: > > > > ********************************************************************** > > * * > > * I E R S B U L L E T I N - A * > > * * > > * Rapid Service/Prediction of Earth Orientation * > > ********************************************************************** > > 29 October 2009 Vol. XXII No. 043 > > > It's got a table showing UT1-UTC for the next week to the microsecond (with > an error column of 5-7 microseconds). It's changing at about 500 to 1000 > microseconds per day so you might want to interpolate. > > > > see: http://www.iers.org/MainDisp.csl?pid=36-9 For longer term data.
Bruce _______________________________________________ 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.
