The telescope of the University of Tokyo Atacama Observatory has a primary mirror with a diameter... more The telescope of the University of Tokyo Atacama Observatory has a primary mirror with a diameter in 6.5m. In order to fabricate the reflecting film initially on the mirror surface and to maintain its optical performance over a long period, a mirror{coating facility will be installed in operation building beside enclosure of the telescope at the summit of Co. Chajnantor (5,640m). The facility consists of mirror coating chamber, cleaning unit for stripping off the old film and clean-up the mirror, and a cart with a lifter for handling the primary mirror cell. Almost all equipment, including the main chamber, was completed by early 2020 and engaged as a mirror coating facility. In order to optimize the coating parameters, comprehensive performance tests were carried out (without primary mirror cell which plays a role of a part of chamber). The evaluation items are how long it takes to reach the target vacuum level and parameters of the current, voltage, and application time during ion...
Ice rich permafrost is observed at Chajnantor volcano (5,640m a.s.l.) on the University of Tokyo ... more Ice rich permafrost is observed at Chajnantor volcano (5,640m a.s.l.) on the University of Tokyo Atacama Observatory (TAO) site. Presence or absence of the permafrost is considered to be requested quite different engineering skills for their infrastructures. Lower altitude boundary is reported to be above 5,079m a.s.l. and maximum active (thawing) layer is 14cm. Minimal seasonal temperature variation, small active layer thickness as the consequences of low numbers of thawing and freezing degree days. Diurnal amplitude results in freeze-thaw cycles only near the surface. Severe frost shattering occurs near the ground surface, producing a dusty, fine-material horizon called a hyper-cryogenic layer. The importance of the snow-covered season for providing great protection for surface energy penetration. Many permafrost hazards are expecting in this construction site such as frost heaving, subsiding, mass movements, erosion, chemical weathering, frost shattering, embankment instability, and
Publications of the Astronomical Society of Japan, 2000
... 0 Q00 joo, .j..0..~ 0 - : o ooi 000 - 0 0 11111111 -6-4-2 0 2 4 6 8 10 T 5. Discussion 5.1. .... more ... 0 Q00 joo, .j..0..~ 0 - : o ooi 000 - 0 0 11111111 -6-4-2 0 2 4 6 8 10 T 5. Discussion 5.1. ... The surface mass density, ~:(9), is normalized to a dimensionless surface mass density, ic, by k(6) = ~(9)/~crit and the critical mass density is defined as C2 D~ ~crit ~ DiDi~ ` (1) where D~, D1 ...
We report on infrared imaging observations of the z=2.429 radio galaxy B3 0731+438 with the Subar... more We report on infrared imaging observations of the z=2.429 radio galaxy B3 0731+438 with the Subaru telescope. The images were taken with the K'-band filter and the 2.25 um narrow-band filter to examine the structure and properties of the Ha+[N II] 6548,6583 emission-line components. The Ha+[N II] emission-line image shows biconical lobes with an extent of 40 kpc, which are aligned with the radio axis. The rest-frame equivalent widths of the emission lines at these cones are as large as 1100 AA, and can be well explained by a gas-cloud model photoionized by power-law continuum radiation. The isotropic ionizing photon luminosity necessary to ionize the hydrogen gas in these cones amounts to 1e57(photons/s), which is larger than that in the majority of radio-loud QSOs. From these results, we propose that the Ha alignment effect in this object is produced by biconical gas clouds, which are swept up by the passage of radio jets, and are ionized by strong UV radiation from a hidden AG...
We have developed a near infrared camera called ANIR (Atacama Near InfraRed camera) for the Unive... more We have developed a near infrared camera called ANIR (Atacama Near InfraRed camera) for the University of Tokyo Atacama 1.0m telescope installed at the summit of Co. Chajnantor (5640m altitude) in northern Chile. The camera is based on a PACE HAWAII-2 array with an Offner relay optics for re-imaging, and field of view is 5. ′ 3 × 5. 3 with pixel scale of 0. 31/pix. It is also capable of optical/infrared simultaneous imaging by inserting a dichroic mirror before the focal plane. The high altitude and extremely low water vapor (PWV=0.5mm) of the site enables us to perform observation of hydrogen Paschen-α (Paα) emission line at 1.8751 μm. The first light observation was carried out in July 2009, and we have successfully obtained Paα images of the Galactic center using the N1875 narrow-band filter. This is the first success of Paα imaging of a Galactic object from a ground based telescope. System efficiencies for the broad-band filters are measured to be 15% at the J-band and 30% at Ks...
An extended version of cross-bar type addressing technique is developed for three-port electrosta... more An extended version of cross-bar type addressing technique is developed for three-port electrostatic micro shutters arranged in an arrayed format. A microelectromechanical systems (MEMS) shutter blade suspended by a pair of torsion beams works as a movable electrode that is either attracted upwards to the cover plate to close the aperture or retracted downwards into the through-hole to open it. Tri-state positioning of the shutter—i.e., open, rest, and close—is controlled by the hysteresis loop of the electrostatic pull-in and release behavior using the combination of the voltages applied to the shutter, the cover, and the substrate. Random access addressing of the shutters is demonstrated by a control system composed of MATLAB-coded Arduino electronics. The shutter array developed in this work is for a sub-cluster of a reconfigurable shutter array under development for a multi-object galactic astronomy.
In this dissertation talk, I will discuss my work to provide improved constraints on the star for... more In this dissertation talk, I will discuss my work to provide improved constraints on the star formation history of the universe by (1) using narrow-band filters to identify galaxies to z 2.2 and (2) extending the Lyman break technique to z=1.5-3. These techniques efficiently isolate a large population of star-forming galaxies and enable measurement of the star formation rate via
The telescope of the University of Tokyo Atacama Observatory has a primary mirror with a diameter... more The telescope of the University of Tokyo Atacama Observatory has a primary mirror with a diameter in 6.5m. In order to fabricate the reflecting film initially on the mirror surface and to maintain its optical performance over a long period, a mirror{coating facility will be installed in operation building beside enclosure of the telescope at the summit of Co. Chajnantor (5,640m). The facility consists of mirror coating chamber, cleaning unit for stripping off the old film and clean-up the mirror, and a cart with a lifter for handling the primary mirror cell. Almost all equipment, including the main chamber, was completed by early 2020 and engaged as a mirror coating facility. In order to optimize the coating parameters, comprehensive performance tests were carried out (without primary mirror cell which plays a role of a part of chamber). The evaluation items are how long it takes to reach the target vacuum level and parameters of the current, voltage, and application time during ion...
Ice rich permafrost is observed at Chajnantor volcano (5,640m a.s.l.) on the University of Tokyo ... more Ice rich permafrost is observed at Chajnantor volcano (5,640m a.s.l.) on the University of Tokyo Atacama Observatory (TAO) site. Presence or absence of the permafrost is considered to be requested quite different engineering skills for their infrastructures. Lower altitude boundary is reported to be above 5,079m a.s.l. and maximum active (thawing) layer is 14cm. Minimal seasonal temperature variation, small active layer thickness as the consequences of low numbers of thawing and freezing degree days. Diurnal amplitude results in freeze-thaw cycles only near the surface. Severe frost shattering occurs near the ground surface, producing a dusty, fine-material horizon called a hyper-cryogenic layer. The importance of the snow-covered season for providing great protection for surface energy penetration. Many permafrost hazards are expecting in this construction site such as frost heaving, subsiding, mass movements, erosion, chemical weathering, frost shattering, embankment instability, and
Publications of the Astronomical Society of Japan, 2000
... 0 Q00 joo, .j..0..~ 0 - : o ooi 000 - 0 0 11111111 -6-4-2 0 2 4 6 8 10 T 5. Discussion 5.1. .... more ... 0 Q00 joo, .j..0..~ 0 - : o ooi 000 - 0 0 11111111 -6-4-2 0 2 4 6 8 10 T 5. Discussion 5.1. ... The surface mass density, ~:(9), is normalized to a dimensionless surface mass density, ic, by k(6) = ~(9)/~crit and the critical mass density is defined as C2 D~ ~crit ~ DiDi~ ` (1) where D~, D1 ...
We report on infrared imaging observations of the z=2.429 radio galaxy B3 0731+438 with the Subar... more We report on infrared imaging observations of the z=2.429 radio galaxy B3 0731+438 with the Subaru telescope. The images were taken with the K'-band filter and the 2.25 um narrow-band filter to examine the structure and properties of the Ha+[N II] 6548,6583 emission-line components. The Ha+[N II] emission-line image shows biconical lobes with an extent of 40 kpc, which are aligned with the radio axis. The rest-frame equivalent widths of the emission lines at these cones are as large as 1100 AA, and can be well explained by a gas-cloud model photoionized by power-law continuum radiation. The isotropic ionizing photon luminosity necessary to ionize the hydrogen gas in these cones amounts to 1e57(photons/s), which is larger than that in the majority of radio-loud QSOs. From these results, we propose that the Ha alignment effect in this object is produced by biconical gas clouds, which are swept up by the passage of radio jets, and are ionized by strong UV radiation from a hidden AG...
We have developed a near infrared camera called ANIR (Atacama Near InfraRed camera) for the Unive... more We have developed a near infrared camera called ANIR (Atacama Near InfraRed camera) for the University of Tokyo Atacama 1.0m telescope installed at the summit of Co. Chajnantor (5640m altitude) in northern Chile. The camera is based on a PACE HAWAII-2 array with an Offner relay optics for re-imaging, and field of view is 5. ′ 3 × 5. 3 with pixel scale of 0. 31/pix. It is also capable of optical/infrared simultaneous imaging by inserting a dichroic mirror before the focal plane. The high altitude and extremely low water vapor (PWV=0.5mm) of the site enables us to perform observation of hydrogen Paschen-α (Paα) emission line at 1.8751 μm. The first light observation was carried out in July 2009, and we have successfully obtained Paα images of the Galactic center using the N1875 narrow-band filter. This is the first success of Paα imaging of a Galactic object from a ground based telescope. System efficiencies for the broad-band filters are measured to be 15% at the J-band and 30% at Ks...
An extended version of cross-bar type addressing technique is developed for three-port electrosta... more An extended version of cross-bar type addressing technique is developed for three-port electrostatic micro shutters arranged in an arrayed format. A microelectromechanical systems (MEMS) shutter blade suspended by a pair of torsion beams works as a movable electrode that is either attracted upwards to the cover plate to close the aperture or retracted downwards into the through-hole to open it. Tri-state positioning of the shutter—i.e., open, rest, and close—is controlled by the hysteresis loop of the electrostatic pull-in and release behavior using the combination of the voltages applied to the shutter, the cover, and the substrate. Random access addressing of the shutters is demonstrated by a control system composed of MATLAB-coded Arduino electronics. The shutter array developed in this work is for a sub-cluster of a reconfigurable shutter array under development for a multi-object galactic astronomy.
In this dissertation talk, I will discuss my work to provide improved constraints on the star for... more In this dissertation talk, I will discuss my work to provide improved constraints on the star formation history of the universe by (1) using narrow-band filters to identify galaxies to z 2.2 and (2) extending the Lyman break technique to z=1.5-3. These techniques efficiently isolate a large population of star-forming galaxies and enable measurement of the star formation rate via
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Papers by Kentaro Motohara