def _get_regular_HD_name(name):
    """Convert an HD name in *Henry Draper Catalogue* to its regular form
    `"HD NNNN"` or `"HD NNNN C"`.
    
    Args:
        name (str or int): Name or HD number of a star (e.g. `"HD8276"`,
            `"HD 8276A"`, `8443`).
    Returns:
        str: Regular HD name `"HD NNNN"` or `"HD NNNN C"`.
    See also:

        * `Henry Draper Catalogue and Extension (III/135A)
          <http://vizier.u-strasbg.fr/cgi-bin/VizieR?-source=III/135A/catalog>`_

    """
    if isinstance(name, str):
        name = name.strip()
        if name[-1].isalpha():
            comp = name[-1]
            return 'HD %d %s'%(int(name[2:-1]), comp)
        else:
            return 'HD %d'%(int(name[2:]))
    elif isinstance(name, int):
        return 'HD %d'%name
    else:
        raise ValueError