sumsig = sum([1 / sig for _, _, sig in data])
nsigs = [1 / sig / sumsig for _, _, sig in data]
avlat = sum([lat * nsig for (lat, _, _), nsig in zip(data, nsigs)])
avlon = sum([lon * nsig for (_, lon, _), nsig in zip(data, nsigs)])
sumsig = sum([1 / sig for _, _, sig in data])
nsigs = [1 / sig / sumsig for _, _, sig in data]
avlat = sum([lat * nsig for (lat, _, _), nsig in zip(data, nsigs)])
avlon = sum([lon * nsig for (_, lon, _), nsig in zip(data, nsigs)])