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A kilosecond (symbol: ks) is 1000 seconds (16 minutes, 40 seconds), so there are 86.4 kiloseconds in a 24-hour day, and 604.8 kiloseconds in a week. The second is the International System of Units (SI) base unit of time, which, combined with the prefix kilo- (which means 1000) results in a kilosecond. Although the metric system dictates the use of the kilosecond, it is rarely used in practice. The more common (though non-decimal) units of minutes (60 seconds) and hours (60 minutes) result in a conversion factor of 3600 when converting seconds to hours. The term kilosecond is most commonly found in astrophysics research articles.

A kilosecond is the longest observation of anti-atom confinement as of 14 April 2011^[update].

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