Gustav Andreas Tammann (24 July 1932 – 6 January 2019) was a German astronomer and academic.
He served as director of the Astronomical Institute of the University of Basel; as a member of the European Space Agency Space Telescope Advisory Team, and as Member of Council of the European Southern Observatory.
Tammann was a former President of the International Astronomical Union Commission on Galaxies.
In 1963 he began a longtime working relationship with Allan Sandage at the Mount Wilson and Palomar observatories.
[1] In 2000 he received the Albert Einstein Medal that is given for "outstanding scientific findings, works, or publications related to Albert Einstein"[2] and the Tomalla Prize for his efforts in measuring the expansion rate of the universe and especially for his pioneering work using Supernovae as standard candles.