def get_event_time(event):
    """
    Get the merger time for known GW events.

    We currently know about:
        GW150914
        LVT151012
        GW151226
        GW170104
        GW170608
        GW170814
        GW170817

    Parameters
    ----------
    event: str
        Event descriptor, this can deal with some prefixes, e.g., '150914', 'GW150914', 'LVT151012'

    Returns
    ------
    event_time: float
        Merger time
    """
    event_times = {'150914': 1126259462.422,
                   '151012': 1128678900.4443,
                   '151226': 1135136350.65,
                   '170104': 1167559936.5991,
                   '170608': 1180922494.4902,
                   '170814': 1186741861.5268,
                   '170817': 1187008882.4457}
    if 'GW' or 'LVT' in event:
        event = event[-6:]

    try:
        event_time = event_times[event[-6:]]
        return event_time
    except KeyError:
        print('Unknown event {}.'.format(event))
        return None