Half a million black holes mapped, and the universe's weirdest spectra still needed a human eyeball

SDSS Data Release 20 delivers the Black Hole Mapper program's first southern hemisphere optical spectra, paired with eROSITA X-ray data, cataloguing roughly 500,000 supermassive black holes and 200,000 X-ray sources. The SPIDERS program provides the largest uniform spectroscopic follow-up of X-ray sources to date, while reverberation mapping and multi-epoch monitoring yield direct black hole mass measurements across cosmic time. All data, tools, and Jupyter notebook tutorials are openly available to researchers and the public worldwide.