GAOES-RV (Gunma Astronomical Observatory Echelle Spectrograph for Radial Velocimetry) is a high-dispersion spectrograph GAOES operated by Gunma Astronomical Observatory 1.5m telescope added a precision radial velocity measurement function for 3.8-m Seimei Telescope in Okayama Observatory of Kyoto University.

Based on the contract signed between Gunma Astronomical Observatory and Tokyo Institute of Technology, it is lent to Tokyo Institute of Technology and installed in the Seimei Telescope.

When installing the GAOES-RV on the Seimei Telescope, an optical fiber transmission system and an image slicer were newly introduced in place of the traditional slit unit of GAOES, and the cross disperser was upgraded to one with a higher dispersion. We also introduced a iodose cell (I₂-cell) for precision radial velocity measurements and a new autoguider. The main components other than these are reused as they are from Gunma Astronomical Observatory.



← The photo on the left is GAOES mounted on GAO 1.5-m telescope during Gunma Astronomical Observatory days [Provided by Gunma Astronomical Observatory].

Exoplanet search by precision radial velocity measurement

Up to the present time, about 50 exoplanets have been discovered by searching exoplanets using the 188 cm telescope at Okayama Astrophysical Observatory of NAOJ and the high-dispersion spectrograph HIDES-F. However, planet search can only be performed efficiently with a 2m-class telescope for stars brighter than 6.5 magnitude, so it is becoming difficult to significantly increase the number of planet discoveries.

By installing the GAOES-RV on the largest 3.8-m Seimei telescope in Japan, it will be possible to efficiently search for exoplanets up to 8 magnitude, Significant progress can be expected in clarifying their statistical properties.

In addition, follow-up observations of transiting exoplanets, which typically have many stars fainter than 10th magnitude, will be newly possible, and new developments in the characterization of transiting exoplanets discovered by the TESS satellite can be expected.

Other general scientific research

As the first high-dispersion spectrograph to be installed on Seimei Telescope, GAOES-RV is expected to be used for stellar atmospheric chemical composition analysis, binary star orbit determination, and stellar activity research.

It is expected that GAOES-RV will be useful in the studies of many kinds of transient astronomical events, taking advantage of the high mobility of Seimei Telescope.