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Arc second - Definition |
| Related Words: Maecenas, Ok, Abettor, Accept, Acolyte, Adjutant, Advance, Advocate, Aficionado, Agent, Alternative, Ambidextrous, Amen, Angel |
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A second of arc or arcsecond is a unit of angular measurement which comprises one-sixtieth of an arcminute, or 1/3600 of a degree of arc or 1/1296000 ≈ 7.7E-7 of a circle. It is the angular diameter on object of 1 unit diameter at a distance of 360×60×60/2/π ≈ 206,265 units, such as (approximately) 1 cm at 2.1 km, or, directly from the definition, 1 astronomical units at 1 parsec .
Correspondingly, 1 radian ≈ 206,265 arcseconds.
The symbol for marking the arcsecond is the double prime (″) (U+2033, ″). One arcsecond would be 1″ (or 1").
It can be abbreviated as arcsec, but should then not be confused with the inverse trigonometric function arc secant, which has the same abbreviation.
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Example Usage of second |
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Breezy_H: i LOVE how the power just flickered and sent my work into the great unknown. T_T ftl. that's the second time in 4 hours. |
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BLee84: Feeling chatty, so can I just say that I don't really want to see Avatar? I know it's the second coming but I want to see Sherlock Holmes. |
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Stuinakilt: This just in: the second Nutcracker show may be cancelled! |
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