The Hubble Source Catalog (HSC) is designed to optimize science from the Hubble Space Telescope by combining the tens of thousands of visit-based source lists in the Hubble Legacy Archive (HLA) into a single master catalog. Version 3 was released on July 5, 2018 and includes many improvements in the photometry and astrometry along with a significant increase in the number of objects and measurements.
The Hubble Catalog of Variables (HCV) is the product of a ESA-funded project at the National Observatory of Athens to identify variable objects using the nearly 30-year baseline of measurements in the HSCv3. The HCV includes more than 84,000 candidate variables as well as 95 million measurements of 3.7 million objects that were selected from the HSC for analysis. The HCV was released on September 24, 2019.