imap_processing.spice.geometry.lo_instrument_pointing

imap_processing.spice.geometry.lo_instrument_pointing(et: float | ndarray[tuple[int, ...], dtype[_ScalarType_co]], pivot_angle: float, to_frame: SpiceFrame, cartesian: bool = False) → ndarray[tuple[int, ...], dtype[_ScalarType_co]]

Compute IMAP-Lo instrument pointing accounting for pivot angle.

This function computes the Lo boresight direction in the specified reference frame, accounting for the instrument’s pivot mechanism. The pivot rotates the boresight about the instrument’s X-axis.

By default, the coordinates returned are (Longitude, Latitude) coordinates in the reference frame to_frame. In the IMAP_DPS frame, Longitude corresponds to spin angle and Latitude corresponds to off-pointing angle.

Parameters:

• et (float or np.ndarray) – Ephemeris time(s) at which to compute instrument pointing.

• pivot_angle (float) – The Lo pivot angle in degrees. Nominal value is 90 degrees.

• to_frame (SpiceFrame) – Reference frame in which the pointing is to be expressed. Typically SpiceFrame.IMAP_DPS for spin angle / off-pointing calculations.

• cartesian (bool) – If set to True, the pointing is returned in Cartesian coordinates. Defaults to False.

Returns:

pointing – The instrument pointing at the specified times. If cartesian=False (default): returns (longitude, latitude) in degrees. If cartesian=True: returns (x, y, z) unit vectors.

Return type:

np.ndarray