def beampars_asec_fromhdr(hdrin):
    """
    Returns beam parameters [BMAJ (arcsec), BMIN (arcsec), BPA (deg)] from input header
    
    Parameters
    ----------
    hdrin : astropy.io.fits.header
        Header object
    Returns
    -------
    list
        [BMAJ_asec, BMIN_asec, BPA_deg]
    """
    return [hdrin['BMAJ'] * 3600.0, hdrin['BMIN'] * 3600.0, hdrin['BPA']]
