THE OPTICAL NEAR-INFRARED COLORS OF BROAD ABSORPTION-LINE QUASARS, INCLUDING THE CANDIDATE RADIO-LOUD BROAD ABSORPTION-LINE QUASAR-1556+3517/

A candidate radio-loud broad absorption line (RLBALQ) has been recentl y reported by Becker et al. We present JHK observations of this object and three other radio-detected BALQs taken with the new Michigan-Dart mouth-MIT/Ohio State/Aladdin Infrared Camera (MOSAIC) on the KPNO 4 m telescope. The candidate RLBALQ 1556+3517 has B - K = 6.63, redder tha n all but one or two known z > 1 quasars. This strongly suggests that the observed continuum of this quasar is reddened by dust. Even when t his extreme reddening is taken into account, 1556+3517 is still probab ly radio loud, although near-infrared spectroscopy to measure its Balm er decrement will be needed to verify this. In addition, since it is a flat-spectrum object, VLBI observations to determine the extent (if a ny) to which beaming affects our estimate of its radio luminosity will be needed before 1556+3517 can be unequivocally declared a radio-loud BALQ. We also use our data and data from the literature to show that optically selected BALQs as a class have B - K colors consistent with the observed distribution for optically selected quasars as a whole. T hus, there is currently no evidence that the tendency of optically sel ected BALQs to be preferentially radio intermediate (see the work of F rancis, Hooper, and Impey) is due to extinction artificially lowering estimated BALQ optical luminosities. However, as most quasar surveys, both radio and optical, would be insensitive to a population of redden ed radio-quiet BALQs, the existence of a large population of reddened BALQs similar to 1556+3517 cannot yet be ruled out.