We identify a strong lensing galaxy in the cluster IRC 0218 that is spectroscopically confirmed to be at z = 1:62, making it the highest-redshift strong lens galaxy known. The lens is one of the two brightest cluster galaxies and lenses a background source galaxy into an arc and a counterimage. With Hubble Space Telescope (HST) grism and Keck/LRIS spectroscopy, we measure the source redshift to be zS = 2:26. Using HST imaging, we model the lens mass distribution with an elliptical power-law prole and account for the effects of the cluster halo and nearby galaxies. The Einstein radius is θE = 0.38+0.02-0.01" (3.2+0.2 -0.1 kpc) and the total enclosed mass is Mtot(< θE) = 1.8+0.2 -0.1 X 1011 M⊙. We estimate that the cluster environment contributes ~ 10% of this total mass. Assuming a Chabrier IMF, the dark matter fraction within θE is fChab DM = 0.3+0.1 -0.3, while a Salpeter IMF is marginally inconsistent with the enclosed mass (fSalp DM = -0.3+0.2 -0.5).

ABSTRACT
1. INTRODUCTION
2. OBSERVATIONS
3. MODELING THE STRONG LENSING SYSTEM
4. RESULTS
REFERENCES

• Kenneth C. Wong(Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA)/EACOA Fellow)
• Kim-Vy H. Tran(George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics & Astronomy, Texas A&M University, College Station)
• Sherry H. Suyu(Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA))
• Ivelina G. Momcheva(Astronomy Department, Yale University)
• Gabriel B. Brammer(Space Telescope Science Institute)
• Mark Brodwin(Department of Physics and Astronomy, University of Missouri)
• Anthony H. Gonzalez(Department of Astronomy, University of Florida)
• Aleksi Halkola(Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA))
• Glenn G. Kacprzak(Swinburne University of Technology/Australian Research Council Super Science Fellow)
• Anton M. Koekemoer(Space Telescope Science Institute)
• Casey J. Papovich(George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics & Astronomy, Texas A&M University, College Station)
• Gregory H. Rudnick(Department of Physics and Astronomy, The University of Kansas)