def get_common_timestamps(source, target):
    """Return indices of timestamps from source that are also found in target.

    :param source: timestamps from source
    :type source: list of datetime objects
    :param target: timestamps from target
    :type target: list of datetime objects
    :return: indices of timestamps from source that are also found in target
    :rtype: list of ints
    """
    remove_from_source = set(source).difference(target)
    remove_from_source_idxs = [source.index(rm_date) for rm_date in remove_from_source]
    return [idx for idx, _ in enumerate(source) if idx not in remove_from_source_idxs]