Create sequences of a time

Description

The functions for creating a time (or time sequences) measured in Greenwich Mean Time (gmt), Greenwich Sidereal Time (gst), Local Sidereal Time (lst), Local Time (lt).

Usage

1
2
3
4
5
gmt(hour = NULL, minute = 0, second = 0, epoch = Sys.time(), length = 1, by = 1)
gst(jday = jd(), hour = NULL, minute = 0, second = 0,
	 epoch = Sys.time(), length = 1, by = 1)
lst(..., lambda = getOption("longitude"))
lt(hour = NULL, minute = 0, second = 0, epoch = Sys.time(), length = 1, by = 1)

Arguments

jday

Julian Day Number

hour

hour

minute

minute

second

second

epoch

epoch

length

length

by

step in sequence

...

additional arguments

lambda

longitude of the observer, default taken from options

Details

The functions gmt() and lt() are simple time series generators. By default they take current time expressed as local or GMT.

The functions lst() and gst() compute sidereal times for given Julian Day Number and time. Default is for now.

Value

A vector containing times expressed as hours from 00h 00m 00s, of class "time".

Author(s)

Lukasz Komsta

Examples

1
2
3
4
5
6
7
lt()
gmt()
gst()
lst()
options(latitude=51,longitude=22)
lst(jd(2008,01,01),hour=12) # Local Sidereal Time, 1st January 2008 1200 UTC
lst(length=10) # 10 hours ahead sequence from now