Development of Iodine Cells for the Subaru HDS and the Okayama HIDES: I. Instrumentation and Performance of the Spectrographs

We have developed iodine (I₂) cells for the High Dispersion Spectrograph (HDS) on the Subaru telescope and for the HIgh Dispersion Echelle Spectrograph (HIDES) on the Okayama 1.88m reflector. The cell is put into a compact vacuum vessel, which fits into a small space behind the entrance slit of the HDS. The cell assembly is designed to minimize heat losses from the cell, which is heated during observations, to keep I₂ vapor from condensation. The amount of I₂ in the cell is determined to be best suited for radial-velocity measurements of solar-type stars. We also report on some performances of the HDS and HIDES as well as their instrumental profiles based on tests of our I₂ cells. Lastly, we discuss future improvements of our instruments and data-analysis softwares for I₂ observations, and also describe the scientific goals of our project.