imap_processing.idex.idex_l2a.invert_rise_time_to_velocity#

imap_processing.idex.idex_l2a.invert_rise_time_to_velocity(t_rise: float, t_rise_params: ndarray) → float#

Invert the rise-time calibration to estimate impact velocity.

The rise-time calibration is defined in the forward direction as rise_time = f(velocity). This helper numerically inverts that relation to recover velocity from a fitted rise time.

Parameters:

  • t_rise (float) – Fitted target rise time in microseconds.

  • t_rise_params (np.ndarray) – Calibration parameters for the forward rise-time curve [A, a1, a2, a3, vb, vc, k, m].

Returns:

Estimated impact velocity in km/s, or NaN if the inversion fails.

Return type:

float