MetFns (version 3.2.2)

date_sollong: Calculation of solar longitude

Description

Calculates solar longitude with respect to the equinox of 2000.0 for given date.

Usage

date_sollong(date,prec=4)

Arguments

date

character vector or factor of length one specifying date, given in "%Y-%m-%d %H:%M:%S" format (UTC timezone).

prec

numeric vector specifying number of decimals of calculated solar longitude (between 2 and 5 decimals). By default, it is equal to 4.

Value

sollong returns solar longitude, numeric vector of length one.

Details

Solar longitude is calculated applying VSOP87 theory, using coefficients from data EarthVSOP87B.

References

Meeus, J. (1998). Astronomical algorithms (Second Edition). Willmann-Bell, Inc., Richmond, Virginia, p. 219.

http://neoprogrammics.com/vsop87

See Also

solar.long,sollong_date

Examples

# NOT RUN {
## calculate solar longitude corresponding to March 7, 2016, at 02:41 UTC
date_sollong(date="2016-03-07 02:41")
# }