The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Quasar Survey: Quasar Properties from Data Releases 10 to 12

Abstract We present the quasar catalog from Data Releases 10 to 12 of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Quasar Survey, comprising quasars observed between 2021 September and 2024 June. We robustly identified 11,346 quasars, of which 5386 are newly discovered objects not present in the Million Quasars catalog. This release brings the total number of quasars identified by the 12 yr LAMOST survey to 67,521, of which 29,513 are newly discovered. While the absolute flux calibration for LAMOST quasar spectra from Data Releases 6 to 9 was previously performed using the Sloan Digital Sky Survey (SDSS)/PanSTARRS1 multiband photometric data, the inherent variability of quasars can affect the flux accuracy. To address this limitation, we recalibrated the LAMOST spectra using (quasi-)simultaneous photometric data from Zwicky Transient Facility, which has conducted high-cadence sky monitoring since 2018 March. Based on the recalibrated single-epoch spectra, we estimated the emission-line fluxes, continuum fluxes, and virial black hole masses. These improved spectra facilitate direct comparison with the spectra of common quasars from SDSS, enabling searches for rare quasars, such as changing-look quasars exhibiting the appearance or disappearance of broad emission lines and broad absorption line quasars. The combined dataset of photometry and multiepoch spectra will enhance the detections of active galactic nucleus–related transients, such as Bowen fluorescence flares and extreme variability quasars, thereby improving our understanding of quasar variability.