Tonantzintla Surveys

The still-referenced Tonantzintla Surveys were conducted in the 1950s and 1960s with the 0.7 m Schmidt camera at Mexico's Tonantzintla Observatory, largely looking for flaring stars, and incidentally imaging objects later identified as quasars and Seyfert galaxies. The location, near Mexico City, hundreds of miles south of Texas, covered more of the southern hemisphere than US surveying telescopes, and its surveying began decades before the deployment of the well-known southern hemisphere Schmidt cameras (the UK Schmidt Telescope, the CTIO Schmidt Camera, and the ESO Schmidt Telescope). Discoveries were numbered and some objects are still identified by their Tonantzintla designator.