"Very Wide Field Imager for HOP"

Saku Tsuneta, Satoshi Miyazaki, Hidehiko Nakaya, Toru Yamada, Masanori Iye, Norio Kaifu (National Astronomical Observatory of Japan), Yoshiaki Taniguchi (Tohoku U.), Mamoru Doi, Sadanori Okamura (U. Tokyo), Yuji Ikeda, Norihide Takeyama (Genesia Corporation), Nobuaki Kaido, Koji Yamaguchi (Orbital Engineering Co.), Colin Norman, Holland Ford, Jeff Kruk (JHU), Masumi Ouchi (STScI), Robert Woodruff (Lockheed Martin)

High-resolution high-throughput multi-color wide-field imaging from space allows us to: (1) study origins of galaxy morphology (z=1-2); (2) to map the post-reionization universe of z=5-10; (3) to investigate the nature of dark energy through an efficient search for distant type Ia SNe; and (4) to map the distribution of dark matter and to measure cosmological parameters with weak gravitational lensing. These science drivers can be carried out by the Very Wide Field Imager (VWFI) aboard the Hubble Origins Probe (HOP) with the other onboard science instruments COS and WFC3.

VWFI consists of > 40 2K x 2K CCDs occupying > 2 quadrants of the HOP focal plane with off-axis aberration corrector optics. The astigmatism corrector optics consists of a pair of simple fused-silica prisms optimized and dedicated to each CCD. The FOV of VWFI is > 170 square-arcmin, and the HOP OTA with the corrector delivers stable and high Strehl-ratio images with a 0.05 arcsec CCD pixel size over the wide field of view. CCDs are cooled down to -80 degree C with a mechanical cooling system and an external dedicated radiator. The fully-depleted CCDs to be provided by Hamamatsu Photonics have a demonstrated capability of high quantum efficiency approx. 0.7 at 1 micron. The very high efficiency at red wavelengths makes VWFI exceptionally qualified to pursue the above science drivers. Multiple optimized filters either allocated to each CCDs or with the mechanical filter wheels allow multi-color imaging.

VWFI is currently being studied with US-Japan working group under the auspices of the NASA Origins Probes Study. VWFI is expected to be primarily provided by Japan.

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