Near Infrared Observations of the Environment of FSC10214+4724 with the Keck Telescope
Session 76 -- Keck
Oral presentation, Thursday, 2:30-4:00, Dwinelle 155 Room

## [76.02] Near Infrared Observations of the Environment of FSC10214+4724 with the Keck Telescope

K.Matthews (Caltech), J.Nelson (U.C.Berkeley), B.T.Soifer (Caltech), H.Boesgaard (CARA), J.R.Graham (U.C.Berkeley), W.Harrison, W.Irace (CARA), G.Jernigan (U.C.Berkeley), H.Lewis (CARA), S.Lin, G.Neugebauer (Caltech), M.Sirota, G.Smith (CARA), C.Ziomkowski (Caltech)

The near infrared camera on the Keck telescope has been used in 0.6" seeing to image the field of the most luminous object known in the universe, the z=2.3 IRAS source FSC 10214+4724. The camera uses a state-of-the-art 256x256 InSb array from SBRC to provide a significant field (38"x38", 0.15"/pixel) while well sampling images.

Images were obtained in the broadband 2.0 - 2.3 $\mu$m filter, as well as narrowband filters in and out of the redshifted H alpha emission line. The continuum source shows at least 5 components that appear to be physically associated. These clumps extend over a physical scale of 40 Kpc. A number of faint sources (K$>$21 mag) are also seen within 20" of the central source that might represent galaxies in an associated cluster.

The image in the H $\alpha$ line shows the brightest H $\alpha$ source to be unresolved with an upper limit of 0.3" (3 Kpc). Limits on the H $\alpha$ fluxes of other components in the system are derived.

\bf Acknowledgements \rm

The W.M. Keck Observatory is a scientific partnership between the California Institute of Technology and the University of California. It was made possible by the generous gift of the W.M. Keck foundation, and the support of its president, Howard Keck. We are most grateful for their visionary endowment that has made possible the first of the next generation of telescopes. It is a pleasure to also thank all of the many devoted people whose unflagging efforts have made possible the success of the W.M.Keck Observatory.