On Fri 2009-09-25T09:19:25 -0700, Rob Seaman hath writ: > First, astronomers "at large" continue to use > UTC widely for almost every conceivable purpose - it is precisely that > UTC remains a flavor of Universal Time that permits this.
It's much simpler than that. Since the epoch when central authorities took over time distribution from the individual observatories (at first by telegraph, later by radio, now also by internet) everyone has used a broadcast time scale. The only other option is to buy an atomic chronometer and eschew the rest of the world, which is basically what interferometers and pulsar timing do. We use UTC because that is the internationally approved name for the broadcast time scale -- the scale which all the broadcasters of sovereign time scales have agreed to use as a result of their conformance to ITU-R recommendations. (In this I gloss over the fact that fear of FCC fines for blue language caused many US broadcasters to delay their analog transmissions of hourly time signals even when the only human voices were their own staff, and this was before the widespread deployment of digital radio and its inherent buffering delays. So there is still no option but to use a broadcast time scale, it's just a matter of how many seconds off one can expect to be.) The LIDAR community and some geophysics folks have chosen GPS because that is another broadcast time scale which can be expected to be available to every measurement system with above-ground components. -- Steve Allen <[email protected]> WGS-84 (GPS) UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99855 University of California Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
