The Seimei telescope project and technical developments

Abstract

An overview of the Seimei telescope, a 3.8 m optical infrared telescope located on Mt. Chikurinji in the Okayama prefecture of Japan, is presented. Seimei is a segmented-mirror telescope whose primary mirror consists of 18 petal-shaped segments. The telescope tube supporting the thin segmented mirrors is structurally incorporated within large arc-rails providing the elevation axis. The tube has a light-weight homologous structure designed with a genetic algorithm. The total weight of the telescope tube, including 1.4-ton optics, is only 8 tons. By virtue of its light weight, the telescope is able to point at an object anywhere in the observable sky within one minute. The telescope is operated by Kyoto University in collaboration with the National Astronomical Observatory of Japan (NAOJ). Half of the telescope time is used by Kyoto University. The remaining time is open to the Japanese astronomical community. NAOJ is responsible for the management of the open-use time, including handling of the observation proposals. The telescope is now regularly performing scientific observations on the basis of a variety of proposals.

Discovery of a Long-Duration Superflare on a Young Solar-Type Star EK Draconis with Nearly Similar Time Evolution for H$α$ and White-Light Emissions

“…We conducted optical spectroscopic and photometric monitoring observations of the young solar-type star EK Dra from February to April 2020. The spectroscopic data were obtained by the 3.8-m Seimei telescope (Kurita et al 2020) (see Section 2.2) and photometric data were obtained by Transiting Exoplanet Survey Satellite (TESS ; Ricker et al 2015) (see Section 2.1). Through this campaign, we succeeded in obtaining optical spectroscopic data of two superflares on a solar-type star, simultaneously with TESS photometry.…”

“…We introduce the utilization of low-resolution spectroscopic data from KOOLS-IFU (Kyoto Okayama Optical Lowdispersion Spectrograph with optical-fiber Integral Field Unit; Matsubayashi et al 2019) installed at the 3.8-m Seimei Telescope (Kurita et al 2020) at Okayama Observatory of Kyoto University. KOOLS-IFU is an optical spectrograph with a spectral resolution of R ∼ 2,000 covering a wavelength range from 5800-8000 Å, including the Hα line (6562.8 Å).…”

Starspot Mapping with Adaptive Parallel Tempering. I. Implementation of Computational Code

“…Bright spotted stars have been observed by TESS (Ricker et al 2014), and superflares on hundreds of spotted solar-type stars have been reported (Feinstein et al 2020;Tu et al 2020). Some TESS targets are to be simultaneously observed by the Seimei telescope at Kyoto University (Kurita et al 2020) using the high dispersion spectrograph. This could allow us to obtain informative prior knowledge for conducting starspot modeling of TESS data.…”

Structure of distributed control system in Seimei telescope

“…In Japan, Kyoto University has developed Seimei telescope which is the largest in East Asia [2,3]. Keck telescopes and their copies are the unique segmented primary mirror telescopes which are equipped with the segmented mirror control system [4], and Seimei telescope is essentially the second one in the world.…”

“…Seimei telescope is therefore the first petal-type in the world. The development process and specifications of Seimei telescope and the comparisons with conventional segmented telescopes are summarized in [3].…”