Prescriptions for Correcting Ultraviolet-Based Redshifts for Luminous Quasars at z > 2.15

High-redshift quasars typically have their redshifts determined from rest-frame ultraviolet (UV) emission lines, and more specifically the C IV λ1549 emission line, in many cases. Unfortunately, these lines yield highly uncertain redshift estimates when compared to the estimates obtained from rest-frame optical emission lines. We present near-infrared spectroscopy of 18 luminous quasars at 2.15 < z < 3.70 that allow us to measure their rest-frame optical emission lines and obtain reliable systemic redshift estimates for these sources. This sample, along with an archival sample of 44 quasars with similar properties, was used in a regression analysis to obtain a prescription for correcting and improving UV-based redshift estimates. With our prescribed corrections, we improve the uncertainties on UV-based redshift estimates for high-redshift quasars by ~25%. This improvement corresponds to ~170 km/s in velocity space which can be translated to ~2 Mpc at z = 2.5. This work is supported by National Science Foundation grants AST-1815281 and AST-1815645.