[LEAPSECS] A leap second proposal to consider -- LSEM

Michael Deckers michael.deckers at yahoo.com
Fri Nov 5 15:57:48 EDT 2010



On 2010-11-04 21:46, Zefram wrote:


> .................................... There is a recent near-renaming

> that shows the way: the modern form of Sidereal Time is known as Earth

> Rotation Angle. This name is accurate in some important ways: it's

> specific to Earth, and it's not time at all but an angular measure.


To be precise, Earth Rotation Angle exists _in addition_
to a modern form of Greenwich mean sidereal time, whose
definition uses both ERA and TT. See for example p 16 of
[http://www.usno.navy.mil/USNO/astronomical-applications
/publications/Circular_179.pdf]. The new name denotes a
new concept, the old concept has retained its name.

Michael Deckers.


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