The Return-To-Brightest (RTB) file contains the flux values, in single-precision floating point, for each dwell point in the target acquisition spiral search. The dwell point choosen and the flux at that dwell point is recorded in the header keywords MAPFND and FLUXFND. The RTB file is identified by the extensions ``.D1H'' and ``.D1D''. The data quality file for RTB is identified by the extensions ``Q1H'' and ``Q1D''.
