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, 2017, Measurement Of The Expansion Proper Motions Of The Ou4 Giant Bipolar Outflow To Determine Its Distance And Its True Nature, 1.0, European Space Agency, https://doi.org/10.5270/esa-mff7pnr