calculate_solar_rotate_shift

sunkit_image.coalignment.calculate_solar_rotate_shift(mc, layer_index=0, **kwargs)

Calculate the shift that must be applied to each map contained in a mapsequence in order to compensate for solar rotation.

The center of the map is used to calculate the position of each mapsequence layer. Shifts are calculated relative to a specified layer in the mapsequence. When using this functionality, it is a good idea to check that the shifts that were applied to were reasonable and expected. One way of checking this is to animate the original mapsequence, animate the derotated mapsequence, and compare the differences you see to the calculated shifts. An example use is as follows. If you select data from the SDO cutout service, it is common to not use the solar tracking implemented by this service. This is because (at time of writing) the solar tracking implemented by that service moves the image by single pixels at a time. This is not optimal for many use cases, as it introduces artificial jumps in the data. So with solar tracking not chosen, the selected area is like a window through which you can see the Sun rotating underneath.

Parameters:

• mc (sunpy.map.MapSequence) – The input mapsequence.

• layer_index (int) – The index layer. Shifts are calculated relative to the time of this layer.

• **kwargs – These keywords are passed to the function sunpy.physics.differential_rotation.solar_rotate_coordinate.

Returns:

Quantity, ~astropy.units.Quantity` – The shifts relative to the index layer that can be applied to the input mapsequence in order to compensate for solar rotation. The shifts are given in arcseconds as understood in helioprojective coordinates systems.