Colors and absolute magnitude of the optical afterglow of the short GRB050709

We find that the color indices of the optical afterglow (OA) of the short GRB050709 are consistent with those of the ensemble of 25 OAs of the long GRBs. This suggests that the spectral profiles of the OAs of both kinds of GRB are similar to each other and that the reddening inside their host galaxies is quite small (EB-V < 0.2). The k-corrected R band absolute magnitude of the OA of GRB050709 in (t - T-0)rest = 2.13 days (i.e. in the rest frame of the GRB) is M-R approximate to -16.7, which is considerably fainter than that of the ensemble of the OAs of the long GRBs studied by [13]. This can suggest that the properties of a fireball do not depend very much on the phenomenon which originated it while the intensities differ considerably.