def METHOD_NAME(self, fileName, transectName):
    """
    read in the data sets for observations, and possibly rename some
    variables and dimensions
    Parameters
    ----------
    fileName : str
        observation file name
    transectName : str
        transect name
    Returns
    -------
    dsObs : ``xarray.Dataset``
        The observational dataset
    """
    # Authors
    # -------
    # Xylar Asay-Davis
    with open(fileName) as filePointer:
        jsonFile = json.load(filePointer)
        for feature in jsonFile['features']:
            if feature['properties']['name'] != transectName:
                continue
            assert(feature['geometry']['type'] == 'LineString')
            coordinates = feature['geometry']['coordinates']
            lon, lat = zip(*coordinates)
            break
    dsObs = xarray.Dataset()
    dsObs['lon'] = (('nPoints',), numpy.array(lon))
    dsObs.lon.attrs['units'] = 'degrees'
    dsObs['lat'] = (('nPoints',), numpy.array(lat))
    dsObs.lat.attrs['units'] = 'degrees'
    return dsObs