challenge: What was used to follow up on the observations of HD 80606 after its variable radial velocity was first noticed?
  
  A. The Spitzer Space Telescope in the infrared
  B. The ELODIE spectrograph mounted on the 1.93-m telescope at the Haute-Provence Observatory
  C. The 10-m Keck 1 telescope at the W. M. Keck Observatory
  D. The Very Large Array in the millimeter radio
  Answer: 