def is_stdstars(header):
    """ Tests if the 'OBJECT' of the given header is associated with a Standard star exposure. (True / False)
    None is returned if the header do not contain an 'OBJECT' entry 

    Returns
    -------
    bool or None
    """
    obj = header.get("OBJECT",None)
    if obj is None:
        return None

    stdnames = ["STD","Feige", "Hitlner", "LTT"]
    return any([s_ in obj for s_ in stdnames])