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arXiv · 1905.05430

KOOLS--IFU: Kyoto Okayama Optical Low-dispersion Spectrograph with Optical-Fiber Integral Field Unit

Kazuya Matsubayashi·Kouji Ohta·Fumihide Iwamuro·Ikuru Iwata·Eiji Kambe·Hironori Tsutsui·Hideyuki Izumiura·Michitoshi Yoshida·Takashi Hattori
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Abstract

Observations of transient objects, such as short gamma-ray bursts (GRBs) and electromagnetic counterparts of gravitational wave sources, require prompt spectroscopy. To carry out prompt spectroscopy, we developed an optical-fiber integral field unit (IFU) and connected it with an existing optical spectrograph KOOLS. KOOLS with IFU, hereafter KOOLS--IFU, was mounted on the Okayama Astrophysical Observatory 188-cm telescope. The fiber core and cladding diameters of the fiber bundle are 100 $μ$m and 125 $μ$m, respectively, and 127 fibers are hexagonally close-packed in the sleeve of the two-dimensional (2D) fiber array. We conducted test observations to measure the KOOLS--IFU performance and obtained the following conclusions: (1) the spatial sampling is 2''.34 $\pm$ 0''.05 per fiber, and the total field of view (FoV) is 30''.4 $\pm$ 0''.65 with 127 fibers; (2) the observable wavelength and the spectral resolving power of the grisms of KOOLS are 4030--7310 A and 400--600; 5020--8830 A and 600--900; 4160--6000 A and 1000--1200; and 6150--7930 A and 1800--2400, respectively; and (3) the estimated limiting magnitude is 18.2--18.7 AB mag during 30-min exposure under the optimal condition.

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Kazuya Matsubayashi, Kouji Ohta, Fumihide Iwamuro, Ikuru Iwata, Eiji Kambe, Hironori Tsutsui, Hideyuki Izumiura, Michitoshi Yoshida, Takashi Hattori. 2019-05-14. KOOLS--IFU: Kyoto Okayama Optical Low-dispersion Spectrograph with Optical-Fiber Integral Field Unit. https://doi.org/10.1093/pasj%2Fpsz087

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