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GV EXTERIOR ZOOM IN U.S. Naval Observatory building
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CU INTERIOR Control panel (3 shots)
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CU Graphic display
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SV's and SCU's scientists check graphs
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EXTERIOR OF U.S. NAVAL OBSERVATORY BUILDING: ATOMIC CLOCK CONTROL PANELS AND GRAPHIC DISPLAYS: SCIENTISTS CHECKING READ-OUTS.




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Script is copyright Reuters Limited. All rights reserved

Background: On Friday (30 June) an extra second was added to the usual twenty-four hours in a day. This was done to bring atomic time, the international standard for time, in line with the less reliable rotation of the earth.

This correction, which effects time computations around the world, was carried out in Washington, D.C. by the National Bureau of Standards who coordinated with other facilities having atomic clocks.

Until the development of the atomic clock the rotation of the earth was considered the most precise measure of time. But, since the atomic clock came into use, scientists have discovered that they are six-tenths of a second ahead of the earth's rotation. It was in order to keep atomic time in phase with earth time that the extra second was added.

The atomic clocks themselves were not changed, but the added second corrected clocks all over the world; clocks used in navigation at sea, at space tracking stations and in other places where extremely accurate time is necessary.

SYNOPSIS: In the U.S. Naval Observatory in Washington, D.C. there are sixteen atomic clocks....the most accurate time keepers in the world. It was because of these clocks that Friday had an extra second in it. The second was added to bring atomic time in line with the less reliable rotation of the earth. Since the atomic clock has come into use, scientists have found that the clocks are six-tenths of a second ahead of the earth's rotation, To even-out this discrepancy, the second was added.

The atomic clocks were not changed to add the second, but clocks around the world were adjusted to conform with the atomic clocks....Scientists monitored the atomic clock so that the compensation would be made at exactly midnight. The one second difference is necessary for clocks used in navigation at sea and at space tracking stations where differences of a second are critical.