sweetcat.py 文件源码

def absolute_magnitude(parallax, m):
    """Calculate the absolute magnitude based on distance and apparent mag.
    Inputs
    ------
    parallax : float
      The parallax in mas
    m : float
      The apparent magnitude

    Output
    ------
    M : float
      The absolute magnitude
    """
    d = 1. / (parallax*1e-3)  # Conversion to arcsecond before deriving distance
    mu = 5 * np.log10(d) - 5
    M = m - mu
    return M