The first light of the Subaru Telescope: A new infrared image of the Orion Nebula

This paper describes the first light and subsequent test observations with the 8.2 in aperture Subaru Teleseope constructed at the summit of Mauna Kea. Following the engineering first light, which started 1998 December, the astronomical first light and test observations were carried out in 1999 January with 4 testing instruments under seeing conditions of 0.″2-0.″5 for near-infrared and 0.″3-0.″6 for optical wave-lengths. The actively supported primary mirror was shown to achieve an overall imaging performance of 0.″1 (FWHM) or better in the absence of any atmospheric disturbance. The pointing accuracy of the telescope is about 1″ rms, and a closed-loop tracking accuracy of ≲ 0.″07 rms has been achieved. Infrared images of the Orion Nebula covering 5′ × 5′, obtained with J, K′, and H2 υ = 1-0 S(1) filters, have revealed much finer and fainter details of the BN/KL region, the bright bar, and other conspicuous features compared with previous observations. K′ band photometry of 516 point sources yielded a luminosity function with a peak at K′ ∼ 12 mag with a long tail in K′ ∼ 13 mag down to K′ ∼ 17 mag, suggesting a fairly large number of young brown dwarfs existing in the Trapezium cluster. Several new features around the Orion BN/KL region are also reported.