def _clean_up_spectrometer_df_header(unformatted_spectrometer_df):
    """ Cleans up header of raw spectrometer df, and removes redundant timestamp column.

    Args:
        unformatted_spectrometer_df: a pandas df of original spectrometer data,
            imported with _import_spectrometer_txt()

    Return:
        A pandas df with a sensible header, and only one timestamp column
    """

    timestamp_column, epoch_column = unformatted_spectrometer_df.columns[[0, 1]]
    spectrometer_df_with_clean_header = unformatted_spectrometer_df.rename(
        # Timestamp column is in local time, epoch_time column is in UTC
        columns={timestamp_column: "timestamp", epoch_column: "epoch_time"}
    )
    # 'epoch_time' column is redundant to 'timestamp' column. Remove it
    spectrometer_df_with_clean_header.drop(["epoch_time"], axis=1, inplace=True)

    return spectrometer_df_with_clean_header