gmst1 {astroFns}

GMST1 (Greenwich Mean Siderial Time at 0h, UT1) from UT1 date

Description

Calculate Greenwich Mean Siderial Time at 0h, UT1 (GMST1) from UT1 year, month, and day.

Usage

gmst1(yr = 2012, mo = 1, dy = 1)

Arguments

yr

UT1 year (integer)

mo

UT1 month (integer)

dy

UT1 day (integer)

Details

Function calculates Greenwich Mean Siderial Time at 0h, UT1 (GMST1) given UT1 year, month, and day.

Value

Returns fractional hours of GMST1 with class fracHrs. The corresponding print method gives hh:mm:ss format rounded to n decimal places in seconds by setting options('digits.secs'=n).

Note

Multiply UT1 fractional day by 1.002737909350795 to get fractional sidereal day.

Author(s)

Andrew Harris

References

Explanatory Supplement to the Astronomical Almanac Seidelmann (ed), c. 1992

See Also

ymd2jd

Examples

  out <- gmst1(yr=2012, mo=7, dy=8)
  str(out)
  out