A leap second will be inserted into Coordinated Universal Time (UTC) after 30 June 2012 23:59:59 in order to sustain synchronization of UTC with Earth rotation. The UTC sequence is as follows:
30 June 2012 23:59:59
30 June 2012 23:59:60
1 July 2012 00:00:00
This was issued on 5 Jan 2012 in Bulletin C of the International Earth Rotation and Reference Service (IERS). It has since been promulgated in GPS NANUs, in DoD memoranda and in a few other communications at irregular and reasonably arbitrary intervals.
The consequence of failing to accommodate this event is that orbit in-plane motion and corresponding Earth orientation will both become inaccurate by at least one second until the leap second is properly implemented. This will also affect estimating orbits using time sequences of observations spanning this leap second event. GEO satellites might be inaccurate to about 3 km and LEO satellites to about 8 km. How great the discrepancy will be depends on how long one waits to implement the leap second. The probable inaccuracies may be within the collision keep-out zones of many satellites, causing either false alarms or totally missed threat detections.
Operators who diligently anticipate the event will not have any issues. Many operators overlook or forget about the event. This happens because the warnings are either so early that people forget about them or so near the leap second insertion that there is nothing they can do but try to recover. This blog is one of the first attempts to create an effective warning and preparation process.
Does anyone have suggestions on what the frequency and content of the alerts should be? Certainly IERS Bulletin C is not sufficient.
Leap seconds and AGI products overview: http://www.agi.com/leap-second
Accounting for leap seconds in AGI products technical details: http://www.agi.com/resources/faq-system/faq_details.cfm?FAQ_ID=10532
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