Some answers to current questions about the formation and evolution of dwarf galaxies are based on the detection and study of increasingly weak sources. The OSIRIS Tunable filter Emission Line -OTELO- survey is the deepest narrow band exploration to date in terms of minimum detectable line flux and observed equivalent width, allowing the detection of very faint emission line sources. OTELO data complement other broad band, narrow band, and spectroscopic surveys with similar science goals. OTELO scans a window free of strong airglow emission around 918 nm using the red Tunable Filter of the OSIRIS instrument at the 10.4 m Gran Telescopio Canarias, pointing at the most deeply explored Extended Groth Strip region. The catalog obtained from this tomography is correlated with ancillary data ranging from deep X-ray to FIR, including high resolution HST/ACS images, and allows deriving photometric redshifts, dust attenuation estimates and obtaining the morphological classification of the extragalactic objects detected.

The highlights of the first published contributions about OTELO and the main features of its value-added data products -publicly available for the IAC Community by mid of June- will be presented in this seminar.