Document Type


Publication Date


Publication Title

The Astrophysical Journal


Department of Physics and Astronomy


We present 426 epochs of optical monitoring data spanning 1000 days from 2003 December to 2006 June for the gravitationally lensed quasar SDSS J1004+4112. The time delay between the A and B images is tBA . 38: 42: 0 days (2 . 4) in the expected sense that B leads A and the overall time ordering is C-B-A-D-E. The measured delay invalidates all published models. The models probably failed because they neglected the perturbations from cluster member galaxies. Models including the galaxies can fit the data well, but conclusions about the clustermass distribution should await themeasurement of the longer, and less substructure sensitive, delays of the C and D images. For these images, a delay of tCB ’ 681 15 days is plausible but requires confirmation, while delays of tCB > 560 days andtAD > 800 days are required.We clearly detect microlensing of the A/B images, with the delay-corrected flux ratios changing frommB mA . 0: 44 0: 01 mag in the first season to 0: 29 0: 01 mag in the second season and 0: 32 0: 01 mag in the third season.



Original Citation

J. Fohlmeister et al 2007 ApJ 662 62