[time-nuts] On Setting the Astronomical Time

Brooke Clarke brooke at pacific.net
Sun Jun 10 13:32:28 EDT 2007


Just loaded the USNO program Multiyear Interactive Computer Almanac (MICA 2.1) 
  It's an almanac good till about 2050 and also does computations for your 
location and has a star chart.

There are two choices for the time scale either UTC1 or TT (Terrestrial Time).
"TT is the time scale that would be kept by an ideal clock on the geoid - 
approximately, sea level on the surface of the Earth."

Setting your clock using GPS time, or with the known offset UTC is straight 
forward.  Offsetting UTC using the posted value of DUT1 gets you UTC1 good to 
0.1 seconds.  But that's 8 orders of magnitude away from the precision of UTC.

Is there some way to get TT to better than a tenth of a second, or is the earth 
just too sloppy of a time keeper?

Have Fun,

Brooke Clarke

More information about the time-nuts mailing list