def from_jd(jd):
    """Return tuple of ISO (year, week, day) for Julian day"""
    gpsweek = int((jd - 2444244.5) / 7)
    dow = ((jd - 2444244.5) / 7 - gpsweek) * 7
    dow = int(round(dow * 86400) / 86400)
    return gpsweek, dow
