Results of optical monitoring of 5 SDSS double QSOs with the nordic optical telescope

Abstract

We present optical R-band light curves of five SDSS double QSOs (SDSS J0903+5028, SDSS J1001+5027, SDSS J1206+4332, SDSS J1353+1138, SDSS J1335+0118) obtained from monitoring at the Nordic Optical Telescope (NOT) between September 2005 and September 2007. We also present analytical and pixelated modeling of the observed systems. For SDSS J1206+4332, we measured the time delay to be Δτ = 116+4-5 days, which, for a singular isothermal ellipsoid model, corresponds to a Hubble constant of 73 +3-4 km s-1 Mpc-1. Simultaneous pixelated modeling of five other systems for which a time delay has now been previously measured at the NOT leads to H0 = 61.5+8-4 km s-1 Mpc-1. Finally, by comparing light curves of the two images of each system, suitably shifted by the predicted or observed time-delays, we found no evidence of microlensing variability over the course of the monitoring period. © 2009 ESO.