Launched in 1990, the NASA/ESA Hubble Space Telescope remains the premier UV and visible light telescope in orbit. With well over 1.6 million observations from 10 different scientific instruments, the ESA Hubble Science Archive is a treasure trove of astronomical data to be exploited.
European Space Agency, Guinan comma Edward F., 2006, 'Towards an Accurate Calibration of the Galactic Cepheid P-L Zero Point', 1.0, European Space Agency, https://doi.org/10.5270/esa-ugyv37b