This paper describes the first light and subsequent test observations with the 8.2 m aperture Subaru Telescope 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*#x2013;0″.5 for near-infrared and 0″.3–0″.6 for optical wavelengths. 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 H2v = 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.

The electrophoretic deposition EPD process is one of several ceramic powder assembling technologies using a simultaneous colloidal process and electrochemical driving force. For the further development of the EPD technique, the possibility and the usefulness of preparing a thin and dense ceramic coating on non-electronically conductive porous tubular ceramics using the EPD technique was investigated. La 0.8 Sr 0.2 Co 0.8 Sr 0.2 O 3ࢬd LSCF was used as the deposition material and a porous alumina tube was used as the deposition substrate. Methanol MeOH was suitable as a dispersing medium for the LSCF powder. LSCF particles were positively charged in MeOH. For the fabrication of a uniform EPD layer, the cathode was placed in a porous alumina tube. The insides of the porous alumina tubes were filled with MeOH and the cathode did not make contact with the EPD bath. A 30 mm 200 gm 2 thick uniform LSCF powder coating was obtained by EPD at 100 V for 10 min. After sintering at 1500c C for 5 h, a 20 mm dense membrane was obtained.

We report on the results of optical and near-infrared photometry of the cluster of galaxies A 851 (= CL 0939+4713) carried out as one of the first-light observations of the 8.2 m Subaru telescope on Mauna Kea. Images as sharp as 0″.3 FWHM in K′ and 0″.45 in R were obtained in these observations. The 3σ limiting magnitudes for points sources in 0″.3 seeing with a 0″.6 software aperture were shown to go down to R = 28.1, J = 25.1, and K′; = 24.0, respectively, for about 1 hour integration. Subaru photometry of the galaxies in this cluster has shown in its color-magnitude diagrams a well-defined sequence of the early-type galaxy population that is consistent with the track predicted for a single-burst passive-evolution model of galaxies at z = 0.4. We attempted a morphological classification of galaxies in the Subaru R-band image using the Cin method, and found that discrimination between ellipticals and spirals can be achieved fairly consistently with the types assigned by MORPHs on the HST F702W image down to R < 23. A weak lensing analysis made on the Subaru R-band image yielded a reconstructed surface mass-density distribution that shows a significant maximum corresponding to the peak of the smoothed luminosity distribution of cluster galaxies. We found no significant excess of faint and/or small galaxies in the putative cluster area around the z = 2 quasar and no difference in the colors for galaxies in this area from those in the main cluster either. Two extremely red objects (ERO) with R – K > 6 are newly identified in the field. The colors of the reddest, disk-shaped galaxy R1 are found compatible with those of an unreddened E/S0 galaxy at z = 1.6.

We present high spatial resolution images of the gravitational-lens system PG 1115+080 taken with the near-infrared camera (CISCO) on the Subaru telescope. The FWHM of the combined image is 0″.32 in the K′-band, yielding spatial resolution of 0″.14 after a deconvolution procedure. This is a first detection of an extended emission adjacent to the A1/A2 components, indicating the presence of a fairly bright emission region with a characteristic angular radius of ∼ 5 mas (40 pc). The near-infrared image of the Einstein ring was extracted in both the J and K′ bands. The J – K′ color is found to be significantly redder than that of a synthetic model galaxy with an age of 3 Gyr, the age of the universe at the quasar redshift.

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