First-2MASS sources below the APM detection threshold: A population of highly reddened quasars

We have constructed a sample of bright near-infrared sources that are detected at radio wavelengths but undetected on the first-generation Palomar Observatory Sky Survey (POSSI) plates in order to search for a population of dust-obscured quasars. Optical and infrared spectroscopic follow-up of the sample has led to the discovery of 17 heavily reddened quasars (B - K > 6.5), 14 of which are reported here for the first time. This has allowed us to define a region in the R - K, J - K color plane in which 50% of the radio-selected objects are highly reddened quasars. We compare the surface density of this previously overlooked population to that of ultraviolet-excess radio-selected quasars, finding that they make up similar to 20% of the total quasar population for K less than or similar to 15.5.