The OAJ, located at the Sierra de Javalambre, in Teruel (Spain), is aimed to lead large-sky multi-filter surveys of the Northern hemisphere over the next years. Having started scientific operations in 2015, the OAJ consists of two main telescopes of large field of view (FoV): the 2.5m Javalambre Survey Telescope (JST250) and the 80cm Javalambre Auxiliary Survey Telescope (JAST80), with polychromatic, seeing-limited images in their unobscured FoVs of 7deg² and 3deg², respectively. Both telescopes are equipped with panoramic instrumentation: JPCam (expected to arrive the OAJ in Summer 2016), with ~ 1.2Gpix distributed in a mosaic of 14 large-format CCDs covering 4.7deg² at the JST250 focal plane, T80Cam, at the JAST80 telescope, providing a 2deg² FoV at the focal plane, and JPAS-PF, a replica of T80Cam with modified optics to be installed at the JST250 telescope before the arrival of JPCam. A specific data center for the reduction and archiving of the large volume of date acquired at the OAJ (up to 1.5TB per night when the two telescopes are in operation) completes the main OAJ infrastructures. It deploys a storage capacity of more than 5PBs and a computing power of 450 cores with 3.5TB RAM memory.

The definition, design and construction of the OAJ, its telescopes, instrumentation and data center have been leaded and promoted by Spain, through the Centro de Estudios de Física del Cosmos de Aragón (CEFCA), funded primarily by the Spanish Fondo de Inversiones de Teruel (FITE) and European FEDER funds. Brazil, through the Observatorio Nacional at Rio de Janeiro and the University of Sao Paulo, has contributed significantly to the development and funding of T80Cam, JPAS-PF and JPCam.

During the first years of operation, the OAJ telescopes and cameras will be mostly devoted to conduct the Javalambre Physics of the Accelerating Universe Astrophysical Survey (J-PAS; 2017 - 2024), mapping 8500deg² of the sky with a set of 54 narrow-band contiguous optical filters plus 5 broader ones, and the Javalambre Photometric Local Universe Survey (J-PLUS; 2016 - 2020), covering the same J-PAS sky area with 12 narrow, intermediate and broad-band filters aimed to provide the photometric calibration of J-PAS. Both J-PAS and J-PLUS will provide powerful 3D views of the Universe and unprecedented multicolor information for many fields of the Astrophysics that will be made publicly available to the community as legacy projects.

In September 2014, the Consejo de Política Científica, Tecnológica y de Innovación of the Spanish Ministry of Economy and Competitiveness included the OAJ in the Spanish map of Infraestructuras Científicas y Técnicas Singulares (ICTS). As such, the OAJ offers 20% of Open Time to the astronomical community.