def acknowledgements(name, tag):
    """Returns acknowledgements for space weather dataset

    Parameters
    ----------
    name : string
        Name of space weather index, eg, dst, f107, kp
    tag : string
        Tag of the space waether index

    """
    swpc = ''.join(['Prepared by the U.S. Dept. of Commerce, NOAA, Space ',
                    'Weather Prediction Center'])

    ackn = {'kp': {'': 'Provided by GFZ German Research Centre for Geosciences',
                   'forecast': swpc, 'recent': swpc}}

    return ackn[name][tag]