sunpy.physics.differential_rotation.diff_rot(duration: Unit("s"), latitude: Unit("deg"), rot_type='howard', frame_time='sidereal')[source] [edit on github]

This function computes the change in longitude over days in degrees.

  • duration (Quantity) – Number of seconds to rotate over.

  • latitude (Quantity) – heliographic coordinate latitude in Degrees.

  • rot_type (str) –

    The differential rotation model to use.

    One of:

    howard : Use values from Howard et al. (1990)
    snodgrass : Use values from Snodgrass et. al. (1983)
    allen : Use values from Allen’s Astrophysical Quantities, and simpler equation.

  • frame_time (str) – One of : 'sidereal' or 'synodic'. Choose ‘type of day’ time reference frame.


longitude_delta (Quantity) – The change in longitude over days (units=degrees)



Default rotation calculation over two days at 30 degrees latitude:

>>> import numpy as np
>>> import astropy.units as u
>>> from sunpy.physics.differential_rotation import diff_rot
>>> rotation = diff_rot(2 * u.day, 30 * u.deg)

Default rotation over two days for a number of latitudes:

>>> rotation = diff_rot(2 * u.day, np.linspace(-70, 70, 20) * u.deg)

With rotation type ‘allen’:

>>> rotation = diff_rot(2 * u.day, np.linspace(-70, 70, 20) * u.deg, 'allen')