On Thu 2003-01-30T02:36:24 -0800, Ken Pizzini hath writ: > Even if you > assume that UTC will exist on past the life of the system, don't you > expect that someday better DUT1 estimates will be available than the > 0.1s signals available in WWV, and that future applications might > find these better estimates to be useful?
The specifications for the automatic telescope call for an object to appear within 10 arcsec of the field center after a slew. This is congruent with what the telescope engineers can do with the flexure and hysteresis, but it obviously requires UT1 good to about 0.66 s for targets on the equator. Therefore we do need DUT1, but not to more accuracy than it is provided. Higher cost telescopes may be able to demand tighter specifications. > And this once again brings me back to my perennial question: wouldn't > it be more useful to the astronomical community for time broadcasts to > include an approximation for sidereal-time-at-the-prime-meridian than > an approximation of UT1? It is already being done. The GPS constellation and the orientation of the earth that it uses is expressed in an inertial reference frame. By decree of the IAU, 30 days ago astronomers abolished the three-millenium tradition of the Vernal Equinox in favor of an inertial reference frame for all future astrometry. -- Steve Allen UCO/Lick Observatory Santa Cruz, CA 95064 [EMAIL PROTECTED] Voice: +1 831 459 3046 http://www.ucolick.org/~sla PGP: 1024/E46978C5 F6 78 D1 10 62 94 8F 2E 49 89 0E FE 26 B4 14 93