def hour2str (hr, delimiter=":") :
    """ Transfer hours to hh:mm format string
    args:
        hr: hours, 0.0 to 36.0, will error for negative
        delimiter: char separate deg, min and sec, default is ":"
    returns:
        string hours and minutes, in hh:mm format
    """
    mi = int(round(hr * 60))
    hh = int(mi / 60)
    mm = int(mi % 60)
    s = "{h:02d}{l}{m:02d}".format(h=hh, m=mm, l=delimiter)
    return s