coconut_tools.rotation_angle

Compute Carrington to Stonyhurst rotation angle from magnetogram filenames.

This module parses magnetogram names from different providers (GONG, ADAPT, HMI) and computes the longitudinal rotation needed to align their maps with the Stonyhurst frame used by heliospheric models like EUHFORIA.

Supports: - GONG synoptic and ADAPT (CM/CAR modes), - HMI (with explicit observation time), - Angle computation based on the central meridian difference.

Used during preprocessing to rotate coronal boundary data into the appropriate HEEQ frame.

Functions

compute_rotation_angle(mag_name_path[, date_hmi])

Compute the rotation angle from magnetogram filename.
coconut_tools.rotation_angle.compute_rotation_angle(mag_name_path, date_hmi=None)[source]

Compute the rotation angle from magnetogram filename.

Supports GONG, ADAPT (CM and CAR), and HMI.

Parameters:

  • mag_name_path (str) – Path to the magnetogram file.

  • date_hmi (str, optional) – ISO datetime string used for HMI (e.g. ‘2024-07-01T00:00:00’)

Returns:

Angle alpha in degrees such that lon_heeq = lon_mag - alpha (mod 360) datetime: Observation date of the magnetogram

Return type:

float