Session 84 - QSOs and BL Lacs.
Display session, Wednesday, January 17
North Banquet Hall, Convention Center

[84.16] A Survey for Very High-Redshift Quasars

S. R. Lemley (University of Michigan)

I have been conducting a deep, three color survey for very high redshift quasars and will present information on how my candidates, which are awaiting spectroscopic confirmation, have been selected. The survey involves direct imaging through Gunn gri filters using a 2048 \times 2048 STIS ccd chip and Cerro Tololo's Curtis Scmidt Telescope. Quasar candidates in the range 4.2 < z < 5.4 have been selected based on the detection of the Lyman \alpha line and the strong drop in the spectrum blueward of this. Because of this response, quasars are clearly located away from the stellar locus on g - r vs. r - i diagrams. Quasar candidates with z \approx 4.5 have large values of g - r and values of r - i near zero. The z>5 candidates have large r - i values and g - r values near zero. Before beginning the survey, test observations using this selection method were made of two known quasars with redshifts of 4.5 and 4.7. The quasars were successfully relocated by the technique and several candidates, which will also be observed for spectroscopic confirmation, were selected from those two fields. To date, 13 square degrees have been surveyed.