Kiso Multi-Fiber Spectroscope Project

A multi-Fiber Spectroscope at Kiso Observatory is under consideration as our next inst rument.In this paper we report an overview of our instrument and a scientific target of survey project.We are going to at tach multi-fiber system at the prime focus of Kiso 150m Schmidt telescope.This telescope has some advantage for our project.First, the effciency in survey for the objects, which number density is 0.1 to 10/degree², is higher than other multi object system due to the wide field of view (6 °×6 °).Second, an optics of telescope is well-matched to fiber numerical aperture (NA)at an input end of fiber.Moreover, taking a focal ratio degradation (FRD)and scrambling property into account, since the light from object does not move at the entrance slit of spectroscope, we could get spect roscopic data stably with this system.We select a fiber with 100μm core which corresponding to 6 arcsec on focal plane, that is matched with a typical seeing (3 arcsec)at Kiso Observatory and set 150 fibers to one field.For efficient observations, it is necessary to arrange fibers accurately within an accuracy of ±25μm on the curved focal plane during a typical exposure time (1 hour).Therefore we examine a particular positioner specialized for curved surface.We also develop a spectroscope that is suited for a fast focal ratio and proceed with making its design.One of our main key projects with this system is a non-biased survey for solar neighbour stars.We are now establishing a new metallicity determination method that easily and reliably measures a metallicity from low-dispersion spectra.(see Itoh it et al.1998)As we consider our main target as Galactic objects and low resolution (R is around 1000), we could observe a star with 17 mag at V-band (1 hour exposure).