gmt: Create sequences of a time

In moonsun: Basic astronomical calculations with R

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

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

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

Example output

         time
1  9h 20m 26s
         time
1  9h 20m 26s
         time
1  7h  9m 15s
         time
1  7h  9m 15s
Warning message:
In lst() :
  Your longitude is not set in the environment, assuming it is equal to 0
         time
1 20h 10m  5s
          time
1   8h 37m 15s
2   9h 37m 15s
3  10h 37m 15s
4  11h 37m 15s
5  12h 37m 15s
6  13h 37m 15s
7  14h 37m 15s
8  15h 37m 15s
9  16h 37m 15s
10 17h 37m 15s

moonsun documentation built on May 29, 2017, 12:17 p.m.