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Session 47 - Microlensing.
Display session, Tuesday, January 16
North Banquet Hall, Convention Center

[47.04] The Mass of the Lensing Cluster for the Double QS0 Q0957+561

P. Fischer, G. M. Bernstein (U. Michigan), J. A. Tyson (ATandT Bell Labs), G. Rhee (UNLV)

The wide separation double QSO Q0957+561 is the only lensed object with an accurately measured timed delay. It, therefore, offers a unique opportunity to yield the value of H_0 independently of the usual distance ladder. This requires not only that the time delay be known but that the mass distribution in the lens be understood. The lens consists of a massive galaxy and the small cluster in which it resides. The largest remaining source of uncertainty in the H_0 determination from this system results from the uncertainty in the relative masses of the galaxy and the cluster.

In this poster we will describe direct mass measurements of the cluster based on weak lensing measurements. The data consists of high quality V-band CFHT images (FWHM = 0.6^\prime\prime) containing \sim2000 faint arclets. Arclet inversion allows us to trace the surface mass density out beyond 2^\prime from the lens center. The implications for H_0 will be discussed.

Program listing for Tuesday