Design of the J-PAS and J-PLUS filter systems

Abstract

J-PAS (Javalambre-PAU Astrophysical Survey) is a Spanish-Brazilian collaboration to conduct an innovative photometric survey of more than 8000 square degrees of northern sky using a system of 57 filters, 54 narrow-band (FWHM=13.8 nm) filters continuously populating the spectrum between 370 to 920 nm with 10.0 nm steps, plus 3 broad-band filters. Together with the main J-PAS survey, the collaboration is carrying out J-PLUS (the Javalambre Photometric Local Universe Survey), an all-sky survey using a set of 12 carefully optimized broad- and narrow-band filters that will be used to perform the calibration tasks for the main survey. The J-PAS survey will be carried out using JPCam, a 14-CCD mosaic camera using the new e2v 9.2k-by-9.2k, 10μm pixel detectors, mounted on the JST/T250, a dedicated 2.55-m wide-field telescope at the Observatorio Astrofisico de Javalambre (OAJ) in Teruel, Spain. J-PLUS, on the other hand, will be carried out using a wide field CCD camera (the T80Cam) equipped with a large format STA 1600 CCD (10.5k-by-10.5k, 9μm pixel) and mounted on the JAST/T80, a dedicated 0.83-m wide-field telescope at the OAJ. In both cases, the filters will operate close to, but up-stream from the dewar window in a fast converging optical beam. This optical configuration imposes challenging requirements for the J-PLUS and J-PAS filters, some of them requiring the development of new filter design solutions. This paper describes the main requirements and design strategies for these two sets of filters.