The first light instrument for the JST250 telescope is the Javalambre Panoramic Camera, JPCam, a 14-CCD mosaic camera using large format, 9.2k-by-9.2k, 10μm-pixel Teledyne-e2V detectors. JPCam is installed at the Cassegrain focus of the JST250, providing a FoV of 4.1 square degrees with a pixel scale of 0.2267"/pixel.

JPCam is designed to perform the Javalambre-PAU Astrophysical Survey (J-PAS), a photometric survey of the northern sky. The J-PAS survey uses 56 filters, 54 narrow-band filters (~14.5 nm FWHM) contiguous and equi-spaced between 370 and 920 nm plus 2 broad-band filters to achieve unprecedented photometric redshift accuracies for faint galaxies over ~8000 square degrees of sky.

The filter system of JPCam.

JPCam consists of three main subsystems: the cryogenic camera (CryoCam), the Filter and Shutter Unit (FSU) and the Actuator System (AS).

The design of the three subsystems of JPCam.

CryoCam: the cryogenic camera subsystem comprises a powered dewar window, the 14 scientific CCDs and their associated controllers, the cryostat, the cooling and vacuum systems and the image acquisition electronics and CCD control software. The science CCD mosaic is complemented with 12 auxiliary detectors, 4 for auto-guiding (AG) and 8 for wave-front sensing (WFS) and image quality control. The camera is cryogenically cooled by a continuous flow cryostat system, using liquid nitrogen (LN2) to achieve operating temperatures of -112^oC. A vacuum pump maintains the camera chamber to a pressure at the level of 10^-6 Torr. The CryCam subsystem has been supplied by Teledyne-e2V under contract with the J-PAS collaboration.

Left: JPCam during laboratory tests. Right: 3D-model of the focal plane of JPCam, showing the 14 science detectors and 12 auxiliary detectors. (Credits: Teledyne-e2V, CEFCA).

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Filter and Shutter Unit (FSU): the Filter and Shutter Unit comprises the filter tray exchange mechanism and the shutter. The FSU has been designed to admit 5 filter trays, with 14 scientific plus 12 auxiliary filters per tray. This allows all J-PAS filters to be simultaneously installed on the camera so no night-to-night filter exchange is required. Filter trays are selectable remotely. The system has been designed to select and place a filter tray in the optical path in less than 40s. Additionally, each filter tray is designed to be easily and manually removable and exchangeable from the FSU closed frame. The FSU has been designed by the J-PAS collaboration and Astro-EME, USA, and has been supplied by The Vacuum Projects (Spain) and Jaguar Precision Machine (USA). The massive 515mm aperture shutter is from Bonn-Shutter UG.

Left to right: 3D-model of the FSU of JPCam; the tray selection and exchange mechanism; a JPCam filter tray with all of its filters in place.

AS: the actuator system is a controllable hexapod that attaches the cryogenic camera to the telescope and allows to perform fine corrections of the instrument positions in piston, x-y decentering and tip/tilt to compensate for temperature changes and/or mechanical flexures at different telescope and instrument orientations, ensuring optimal image quality across the entire field-of-view. The required corrections are calculated by utilising the 8 wave-front sensor CCDs via an analysis technique developed at CEFCA. The AS has been supplied by Sener (Barcelona, Spain).