QUIJOTE (for Q-U-I Joint Tenerife Experiment)
is a survey begun in 2012 that records the
polarization of the CMB.
Letters Q, U, and I are Stokes parameters,
presumably those characterizing the observed CMB polarization.
The survey is carried out with two special-purpose 2.5-m microwavetelescopes (the QUIJOTE-CMB Telescopes), QT1 and QT2,
located at Teide Observatory on the Canary Islands.
Instruments that have been used: MFI (10-20 GHz), TGI (30 GHz) and FGI (40 GHz).
They incorporate polarimeters.
An earlier (CMB-related) Tenerife Experiment was carried out
at that site some years earlier, in the 1980s-1990s.