import math


def LST_to_HA(LSTs, RA):
    """
    RA [degrees] - right ascenction
    LST [fr. of days] - local sidireal time
    Returns Hour Angle [rads]
    """

    HAs = list()

    RA_rad = RA * math.pi / 180.

    for LST in list(LSTs):
        HA = 2. * math.pi * LST - RA_rad
        HAs.append(HA)

    return HAs