CHAPTER 11 REDSHIFTS AND VELOCITY DISPERSIONS SUMMARY OF THE BASIC CCF ROUTINES USED TO GET REDSHIFTS AND VELOCITY DISPERSIONS To cross correlate rows in a spectral map with a template row use: MA Masks maps and include template (output map has 1 extra row) FT Forward transforms BT Backward transforms CR Cross correlates maps with their template CN Normalizes the CCF CQ Finds the CCF peak (where derivative equals zero) For velocity dispersions: SM Divides the object transform by template transform to give the broadening transform SP Fits a gaussian to the broadening peak REAL and COMPLEX files are used as storage registers to contain your results ie. OPTION MAP REAL COMP FT 1 P(S(k)) S(k) CR 2 P(SxT) S(k)xT(k) BT 3 S*T S(x)*T(x) CN 4 S*T normalised CQ gets the redshifts: MAPIC=3, MAPIR=4