earthvelocity¶
- sofia_redux.spectroscopy.earthvelocity.earthvelocity(ra, dec, time, equinox='J2000', frame='FK5', time_format=None, time_scale=None, lat=None, lon=None, height=0.0, center='heliocentric', definition='kinematic')[source]¶
Provide velocities of the Earth towards a celestial position.
The Local Standard of Rest allows for two different definitions defined by the
definition
keyword:‘kinematic’ uses 20 km/s towards 18:00:00, +30:00:00 (‘J1900’)
‘dynamical’ uses the IAU definition of 9, 12, and 7 km/s along the x, y, and z axis in Galactic cartesian coordinates.
- Parameters:
- rastr or float or Angle or array_like
The right ascension[s] of the position[s]. Default unit is hourangle.
- decstr or float or Angle or array_like
The declination[s] of the position[s]. Default unit is degrees.
- timestr or float or Time or array_like
Time of the observation.
- equinoxstr, optional
Coordinate frame equinox
- framestr, optional
Type of coordinate frame represented.
- time_formatstr, optional
Format of the input
time
. Seeastropy.time
for available formats.- time_scalestr, optional
Time scale of
time
. Seeastropy.time
for available scales.- latstr or float or Latitude or array_like, optional
The latitude of the observation. Default unit is degrees.
- lonstr or float or Longitude or array_like, optional
The longitude of the observation. Default unit is degrees.
- heightstr or float or Quantity, optional
The height of the observation. Default unit is meters.
- centerstr, optional
Defines the center of the Solar System. One of {‘heliocentric’, ‘barycentric’}.
- definitionstr, optional
Defines the Local Standard of Rest (LSR) definition as described above. One of {‘kinematic’, ‘dynamical’}.
- Returns:
- velocitiesdict
vhelio
-> Velocity of the Earth wrt the Sun towards (ra, dec) ‘vsun’ -> Velocity of the Solar motion wrt LSR towards (ra, dec) ‘vlsr’ -> Net radial velocity of the Earth wrt LSR towards (ra, dec)- Note if arrays were passed in, then arrays will be passed out. However,
- all values will be astropy.units.Unit.Quantity with units in km /s.