FK4Coordinates

class astropy.coordinates.builtin_systems.FK4Coordinates(*args, **kwargs)[source] [edit on github]

Bases: astropy.coordinates.coordsystems.SphericalCoordinatesBase

A coordinate in the FK4 system.

Parameters :

coordstr : str

A single string with the coordinates. Cannot be used with dec and ra nor x/y/z.

ra : Angle, float, int, str

This must be given with dec.

dec : Angle, float, int, str

This must be given with ra.

distance : Distance, optional

This may be given with dec and ra or coordstr and not x, y, or z. If not given, None (unit sphere) will be assumed.

x : number

The first cartesian coordinate. Must be given with y and z and not with ra or dec nor coordstr.

y : number

The second cartesian coordinate. Must be given with x and z and not with ra or dec nor coordstr.

z : number

The third cartesian coordinate. Must be given with x and y and not with ra or dec nor coordstr.

cartpoint : CartesianPoints

A cartesian point with the coordinates. Cannot be used with any other arguments.

unit :

The unit parameter’s interpretation depends on what other parameters are given:

  • If ra and dec or coordstr are given:

    unit must be a length-2 sequence specifying the units of ra and dec, respectively. They can be either UnitBase objects or strings that will be converted using Unit. They can also be None to attempt to automatically interpret the units (see Angle for details.) If unit is just None, this will be interpreted the same as (None, None).

  • If x, y, and z are given:

    unit must be a single unit with dimensions of length

equinox : Time, optional

The equinox for these coordinates. Defaults to B1950.

obstime : Time or None

The time of observation for this coordinate. If None, it will be taken to be the same as the equinox.

Alternatively, a single argument that is any kind of spherical coordinate :

can be provided, and will be converted to `FK4Coordinates` and used as this :

coordinate. :

Attributes Summary

equinox
latangle
lonangle
obstime

Methods Summary

precess_to(newequinox) Precesses the coordinates from their current equinox to a new equinox.

Attributes Documentation

equinox[source]
latangle[source]
lonangle[source]
obstime[source]

Methods Documentation

precess_to(newequinox)[source] [edit on github]

Precesses the coordinates from their current equinox to a new equinox.

Parameters :

newequinox : Time

The equinox to precess these coordinates to.

Returns :

newcoord : FK4Coordinates

The new coordinate

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