Kavli Affiliate: Fukun Liu| Summary: We present a multi-epoch study of the extreme X-ray variability of the type~1 quasar SDSS~J000532.84+200717.4 using archival observations from textitXMM-Newton, textitSwift/XRT, textitEP-FXT, and textitROSAT, together with new optical spectroscopy and multi-wavelength photometry. The 0.2–10~keV X-ray flux exhibits a transition from a high state to a subsequent low state, declining by […]
Continue.. X-ray variability of SDSS J000532.84+200717.4: from a normal state to an X-weak state