`R/astronomy.R`

`angle2hms.Rd`

The purpose of angle2hms is to facilitate comparison of
`rightAscension`

angles computed by `sunAngle()`

and `moonAngle()`

with angles reported in astronomical sources and software, which
often employ an hour-minute-second notation. In that notation,
decimal hour is computed as 24/360 times the angle in degrees,
and from that decimal hour are compute integer hour and minute
values, plus a decimal second value. It is common in the
astronomical literature to use strings to represent the results,
e.g. with \(11^h40^m48^s.10\) for the
value used in the “Examples”; see Chapter 1 of
Meeuse (1991) for more on angle calculation and representation.

angle2hms(angle)

angle | numerical value giving an angle in degrees |
---|

angle2hms returns a list containing
values `time`

(a numerical value for decimal hour, between 0 and 24),
`hour`

, `minute`

, and `second`

(the last of which may have a fractional
part), and `string`

, a character value indicates the time in hour-minute-second
notation, with the second part to two decimal places and intervening `h`

,
`m`

and `s`

characters between the units.

Meeus, Jean, 1991. Astronomical algorithms. Willmann-Bell, Richmond VA, USA. 429 pages.

Other things related to astronomy:
`eclipticalToEquatorial()`

,
`equatorialToLocalHorizontal()`

,
`julianCenturyAnomaly()`

,
`julianDay()`

,
`moonAngle()`

,
`siderealTime()`

,
`sunAngle()`

,
`sunDeclinationRightAscension()`

# A randomly-chosen example on page 99 of Meeus (1991). angle2hms(177.74208) # string component 11h50m58s.10#> $hourDecimal #> [1] 11.84947 #> #> $hour #> [1] 11 #> #> $minute #> [1] 50 #> #> $second #> [1] 58.0992 #> #> $string #> [1] "11h50m58s.10" #>