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The LST project aims to construct a large-aperture 50m-class telescope in South America, Chile, capable of simultaneously observing a wide field of view and a broad wavelength range in the millimeter and submillimeter wavebands. This project will develop a complementary discovery space to ALMA.



The LST project was planned and proposed based on the development and achievements of Japanese millimeter and submillimeter wave astronomy. The style of setting clear scientific goals and independently researching and developing the necessary technology originates from the early days of Japan's radio astronomy and has been passed down to the new generation. In this sense, the LST is a project that inherits this legacy while encapsulating our originality.


In 1965, the Science Council of Japan's Astronomy Research Liaison Committee began "studying the construction of a space radio observatory centered around a 45m radio telescope." On March 1, 1982, the Nobeyama 45m radio telescope started its open-use operation. Since then, the 45m radio telescope and millimeter-wave interferometer have pioneered a new field of cosmic radio spectroscopy, leading to numerous significant discoveries such as the identification of interstellar molecules, the discovery of molecular bipolar outflows from protostars, the detection of supermassive black holes using water masers, the observation of molecular gas in redshifted distant quasars, and the imaging of protoplanetary disks.
These achievements, in concert with unbiased survey research promoted by other facilities like Nagoya University's 4m radio telescope, the Nanten radio telescope, and the University of Tokyo's 60cm radio telescope (Amanogawa telescope), triggered a wave of comprehensive studies on interstellar matter exhibiting diverse physical properties. By the end of the 20th century, shorter wavelength observational astronomy was pioneered with the Mt. Fuji summit submillimeter-wave telescope, which observed neutral carbon emission lines.
Moreover, the Atacama Submillimeter Telescope Experiment (ASTE) not only achieved molecular spectroscopy observations but also realized Japan's first full-fledged submillimeter galaxy survey using dust continuum waves in the 2000s. These diverse studies have seamlessly continued into research conducted by the Atacama Large Millimeter/submillimeter Array (ALMA), highlighting the prominence of Japan-originated research in numerous international collaborative observatories, epitomized by ALMA


Perhaps each observational astronomer in Japan has unconsciously inherited a certain kind of "gene." This is the perspective of comprehensive observation. This expression likely began with the Schmidt camera at the University of Tokyo's Kiso Observatory and is epitomized by the current trend of wide-field, high-time-resolution science, pioneered by the prime-focus instruments of the Subaru Telescope. The optical and infrared community has sought to observe wavelengths longer than 30 μm, which are challenging to access from the ground, culminating in the all-sky survey conducted by the infrared astronomy satellite AKARI. AKARI's all-sky survey at wavelengths from 1.7 to 180 μm is the first comprehensive sky observation since the infrared astronomy satellite IRAS and stands as a milestone in the history of astronomy.
In the field of radio astronomy, unbiased survey observations conducted in the 1990s with Nagoya University's 4m radio telescope and the University of Tokyo's 60cm radio telescope led to legacy surveys with the Nobeyama 45m radio telescope. The pursuit of unique individual celestial objects based on large samples has produced breakthrough research in various fields. Furthermore, in addition to fields like galaxy and cosmology, this has led to the creation of time-domain astronomy for supernova searches, gravitational wave counterparts, and solar system moving objects, among others. These have developed beyond the initial project concepts, driving global advancements in synergy with theoretical research.


Currently, the expectations for wide-field observations and observations covering a broad range of wavelengths in submillimeter astronomy are not limited to astronomy but are also gathering interest from the fields of planetary science and physics. Researchers primarily focused on optical and infrared astronomy are now forming a significant user base for ALMA, and in the LST project, the optical-infrared community, which has advanced through wide-field and extended wavelength observations, will intersect with the cosmic radio community. Furthermore, we consider it an essential responsibility of the LST to serve as a hub for various fields.



The LST will enable groundbreaking exploration of extremely vast three-dimensional cosmic volumes and bring new advances to time-domain astronomy in millimeter and submillimeter wavelengths. One of the most important scientific goals of the LST is to elucidate the large-scale structure of the universe in three dimensions, from low redshift (nearby universe) to high redshift (distant universe), and to clarify the history of star formation in the universe. To achieve this, we will conduct wide-area spectroscopic surveys of star-forming galaxies using molecular and atomic spectral lines and multi-color imaging surveys of dust (interstellar dust) continuum emission.


Furthermore, the LST has a highly complementary relationship with ALMA. The LST can establish a census of various interesting celestial objects through wide-field surveys. It can also identify intriguing objects for further investigation by ALMA. By leveraging the synergies with ALMA and existing and upcoming missions aimed at optical to infrared surveys, such as the Subaru Telescope's HSC/PFS, TAO, the Rubin Observatory (LSST), the Euclid Space Telescope, and the Roman Space Telescope, the LST can contribute to a wide range of research in astronomy and astrophysics.



大阪府立大学 大妻女子大学 香川大学 鹿児島大学 神奈川大学 北見工業大学 京都産業大学 京都大学 慶應大学 国立天文台 筑波大学 電気通信大学 東京学芸大学 東京大学 東邦大学 徳島大学 名古屋市立大学 名古屋大学 日本工業大学 日本女子大学 日本大学 北海道大学(五十音順)




河野 孝太郎(代表;東京大学) 石井 峻(国立天文台) 大島 泰(国立天文台) 川邊 良平(国立天文台) 竹腰 達哉(北見工業大学) 谷口 暁星(名古屋大学) 田村 陽一(名古屋大学) 古屋 玲(徳島大学) 阪本 成一(国立天文台)


LST Code of Conduct

The LST project declares to act in full according to a code of conduct aimed at facilitating smooth communication with stakeholders.

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