The files c[23]_avg_rollxy_all.txt contains the following information that
may be used for each image that falls before the date indicated in the last 
column:

  avg roll   avg ctr_x   avg ctr_y   avg roll   avg ctr_x   avg ctr_y    Last 
    from       from        from       median      median      median	 Date
    stars      stars       stars  					 Valid