He co-discovered the near - Earth Amor asteroid 1980 Tezcatlipoca during his stay at the Palomar Observatory in California in 1950 .
After his retirement Wallenquist continued to research dark matter in open clusters at the Uppsala Astronomical Observatory .
Wallenquist co-discovered the near - Earth Amor asteroid 1980 Tezcatlipoca during Wallenquist 's stay at the Palomar Observatory in California in 1950 .
After his retirement Wallenquist continued to research dark matter in open clusters at the Uppsala Astronomical Observatory .