4MOST Low Resolution Spectrograph MAIT

摘要

4MOST, the 4m Multi Object Spectroscopic Telescope, is an upcoming optical, fibre-fed, MOS facility for the VISTA telescope at ESO's Paranal Observatory in Chile. Its main science drivers are in the fields of galactic archeology, high-energy physics, galaxy evolution and cosmology. The design of 4MOST features 2436 fibres split into low-resolution (1624 fibres, 370-950 nm, R ＞ 4000) and high-resolution spectrographs (812 fibres, three arms, ～44-69 nm coverage each, R ＞ 18000) with a fibre positioner and covering a hexagonal field of view of ～4.1 deg~2. The 4MOST consortium consists of several institutes in Europe and Australia under leadership of the Leibniz-Institut fuer Astrophysik Potsdam (AIP). 4MOST is currently in its Manufacturing, Assembly, Integration and Tests Phase with an expected start of science operations in 2022. Two third of the fibers (i.e. 1624 for science and 20 for calibration) feed the two Low Resolution Spectrographs hosting three channels each. The fibers used are 85μm core fibers at f/3. Each Low Resolution Spectrograph is composed of a 200mm beam for an off-axis collimator associated to its Schmidt corrector. 3 "color" arms with f/1.73 cameras and standard 6k × 6k 15μm pixel detectors. CRAL has the global responsibility of the Low Resolution Spectrographs. In May 2018, the final design review for the 4MOST Low Resolution Spectrograph was passed successfully. In this paper, the long process from the definition of the technical requirements for all individual opto-mechanical components, the manufacturing, the deliveries up to the first assemblies will be described.