On 2011 Jun 18, at 09:31, Tom Van Baak wrote: > Are the details about UT1 correct in this link? > http://hpiers.obspm.fr/iers/bul/bulb/explanatory.html > > I ask because a number of posters claim UT1 is a measure of > earth angle. At one level this is true, of course, but if I read that > document correctly it says that certain periodic terms have been > removed from UT1. I think that's where the confusion arises -- it > makes UT1 seem more like it's trying to be a clock and less like > a precise measure of angle. > > Perhaps you can clear up the mystery.
It's mostly for practicality and utility. The document indicated there ftp://hpiers.obspm.fr/eop-pc/models/interp.readme gives much of that story. The values of UT1 are published no more often than daily, so in order to facilitate interpolation the higher frequencies are removed from the published values with the expectation that the user will interpolate within the day and then add the high frequencies back. Such a user is likely to be involved with pulsar timing or VLBI or high precision satellite geodesy. -- 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
