Composite image of the OTELO field. The field explored covers a little over 50 square arcminutes, which is the equivalent of 13 times smaller than the full Moon, and is contained within the field known as the Extended Groth Strip, a zone on the sky between the contellation of Ursa Major and Bootes which has been observed deeply using other telescopes and instruments in complementary ranges of the electromagnetic spectrum. In composing the images the colour red has been assigned to the integrated data from OTELO, obtained using the tuneable filters of OSIRIS on the GTC, while the bule and green colours correspond to the g and r bands of the survey made with the Canada-France-Hawaii Telescope respectively.Credit: OTELO.