gary
29-06-2012, 01:53 PM
As announced by the International Earth Rotation and Reference System Service (IERS)
in Paris on 5 January 2012 -
IERS Bulletin here -
http://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat
For those on the east cost of Australia, we are currently +10 hours ahead of UTC
so the leap second will occur on 2012 July 1, at 09h 59m 60s AEST.
When it takes place, you should probably be able to see the leap second occur here -
http://time.gov/timezone.cgi?UTC/s/0/java
* UT1 or Universal Time is based on Earth rotation and was the successor to GMT.
* TAI or International Atomic Time is the time kept by the weighted average of over 200 atomic clocks around the world.
* UTC or Universal Co-ordinated Time is the time standard we all use day to day, is based on TAI but it was agreed in 1972 to keep it within 0.9 seconds of the old UT1 despite the fact the Earth's rotation was slowing in an irregular fashion.
* To keep UTC within the 0.9 second requirement, a leap second is added either at the end of June or the end of December if deemed to be required by the responsible body, which is the International Earth Rotation Service.
A decision on the proposal to abandon leap seconds was delayed by the International Telecommunications Union (ITU) in January 2012 until the World Radio Conference in 2015.
Astronomical observatories (and telescope computer programmers) are mindful of leap seconds because the apparent position of objects in the sky at any one instant is a function of Earth rotation.
There are additional time standards in use as well such as TT or Terrestrial Time
which is defined by the IAU and is commonly used for ephemeris of the Moon
and Sun.
GPST or Global Positioning System Time is that used by the atomic clocks aboard
the GPS satellites and is not corrected for Earth rotation and unlike UTC, does
not contain leap seconds. It was initially synchronized to UTC in 1980 and has
steadily diverged since then and is currently more than 15 seconds ahead of UTC.
in Paris on 5 January 2012 -
IERS Bulletin here -
http://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat
For those on the east cost of Australia, we are currently +10 hours ahead of UTC
so the leap second will occur on 2012 July 1, at 09h 59m 60s AEST.
When it takes place, you should probably be able to see the leap second occur here -
http://time.gov/timezone.cgi?UTC/s/0/java
* UT1 or Universal Time is based on Earth rotation and was the successor to GMT.
* TAI or International Atomic Time is the time kept by the weighted average of over 200 atomic clocks around the world.
* UTC or Universal Co-ordinated Time is the time standard we all use day to day, is based on TAI but it was agreed in 1972 to keep it within 0.9 seconds of the old UT1 despite the fact the Earth's rotation was slowing in an irregular fashion.
* To keep UTC within the 0.9 second requirement, a leap second is added either at the end of June or the end of December if deemed to be required by the responsible body, which is the International Earth Rotation Service.
A decision on the proposal to abandon leap seconds was delayed by the International Telecommunications Union (ITU) in January 2012 until the World Radio Conference in 2015.
Astronomical observatories (and telescope computer programmers) are mindful of leap seconds because the apparent position of objects in the sky at any one instant is a function of Earth rotation.
There are additional time standards in use as well such as TT or Terrestrial Time
which is defined by the IAU and is commonly used for ephemeris of the Moon
and Sun.
GPST or Global Positioning System Time is that used by the atomic clocks aboard
the GPS satellites and is not corrected for Earth rotation and unlike UTC, does
not contain leap seconds. It was initially synchronized to UTC in 1980 and has
steadily diverged since then and is currently more than 15 seconds ahead of UTC.