NavList:

"What is the delta T about in this program?" -Samuel

Samuel,

Delta-T is the difference between "Terrestrial Time" (or "Ephemeris Time") and Coordinated Universal Time (UTC). Basically, it's the difference between the theoretical "regular" time rate used by the program and the ever-changing "real" time as experienced on Earth due to, among other things, the slowing of the Earth's rotation.

More info, as well as the current Delta-T value, can be found by exploring the USNO "Earth Orientation Products" website here:

http://www.usno.navy.mil/USNO/earth-orientation/eo-products

Definitions can be found here:

http://www.usno.navy.mil/USNO/earth-orientation/eo-info/general/date-time-def

-Sean C.
----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------