def hms2h(h = 0, m = 0, s=0)  : 
    """Converts from hours, minutes and seconds to decimal hours
    Used for Right Ascension within a range  [0h0m0s -> 23h59h59s]

    Parameters
    ----------
    h : float, optional
        hours, by default 0
    m : float, optional
        minute, by default 0
    s : float, optional
        seconds, by default 0

    Returns
    -------
    float
        decimal hours
        None for negative values.
    """
    if 0 <= h < 24 :
        if 0 <= m < 60 :
            if 0 <= s < 60 :
                value = h + m/60 +  s/3600
                return value