Lo - magic offset between viewing direction and RAM direction

[vineetbansal]

This offset in imap_processing/lo/constants.py comes directly from the Lo dropbox pipeline and has no explanation of how it came about or why it exists:

    # Empirical offset [degrees] added to the measured pivot angle when
    # projecting a look direction onto the RAM direction.
    PIVOT_RAM_OFFSET: float = 4.0

It is used in L2 maps as:

    ram_projection = np.sin(np.radians(pivot_angle + c.PIVOT_RAM_OFFSET)) * np.sin(
        np.radians(spin_angles)
    )