; docformat = 'rst' ;+ ; Return lookback time to z, in years ; ; See ajs_comdis for keyword parameters ; :Params: ; z, in, required ; Redshift (or array of values) ; :Keywords: ; h0, in, optional ; Hubble constant (default 70) ; :History: ; 10 Oct 2008 Written, Anthony Smith ;- FUNCTION ajs_lookback_time, z, h0=h0, _REF_EXTRA=e compile_opt idl2 IF n_elements(h0) EQ 0 THEN $ h0 = 70 return, ajs_comdis(z, /lookback_time, h0=h0, _strict_extra=e) $ / 60. / 60. / 24. / 365.25 END