Author Submission

  Conference: 
        Ground-Based Instrumentation (AS06)
  Chairs: 
        Masanori Iye 
        Alan Moorwood 



   Submitted: Nov/24/2003 


   Title:
   Infrared Multi-Object Spectrograph of MOIRCS

   Author:
   Chihiro Tokoku, Ryuji Suzuki, Koji Omata, Tetsuo Nishimura

   Abstract:
   MOIRCS (Multi-Object Infrared Camera and Spectrograph) is 
   one of the second generation instruments for the Subaru 
   Telescope and provides imaging mode with 4' x 7' field of 
   view and low/medium-resolution multi-object spectroscopy 
   mode for the wavelength range from 0.85 to 2.5 micrometers.
   This paper describes the design, development, operation 
   and test observation results of its multi-object spectroscopy 
   (MOS) mode. 
   The MOS mode uses cooled multi-slit masks and a mask 
   exchange system in cryogenic environment. The masks are 
   housed in a vacuum dewar attached to the MOIRCS main dewar
   and separated by a large gate valve. The mask dewar is equipped 
   with its own cryogenic cooler and a vacuum pump and can 
   store twenty-four masks. The masks are made of thin aluminum film. 
   Slits are cut with an electric discharge machine (EDM). For slit 
   cutting coordinates, the software corrects the effects of 
   the thermal contraction and distortion of the optical system.
   The masks are cooled down to below 150 K in the mask dewar 
   and transported to the focal plane in the main dewar through
   the gate valve with a linear motion manipulator as needed 
   for MOS observation. Replacing the masks can be done in a 
   daytime without breaking vacuum of the main dewar by isolating 
   the mask dewar by closing the gate valve.  This system 
   provides multi-object spectroscopy up to more than fifty 
   objects at a time and up to K-band by the use of two 
   HAWAII 2 MCT arrays.
   The observation of the MOS mode starts in March 2004.



   Principal Author Affiliation: 
   Subaru Telescope
   650 North A'ohoku Place
   Hilo , HI 96720 
   U.S.A. 
   Phone: +1-808-934-5080
   Fax: +1-808-934-5984

   Principal Author Biography:
   Chihiro Tokoku is a graduate student of Astronomical Institute,
   Tohoku University. She received the B.S. in Physics from Tokyo
   Metropolitan University in 1998, and the M.S. in Astronomy from
   Tohoku University in 2001. Her research interests are observational
   study of large scale structure and galaxy evolution in the early
   universe. She is currently working on the development of MOIRCS
   for the Subaru Telescope and hopes to utilize the instrument for
   her research goals. 

   Correspondence for Secondary Authors:
   Ryuji Suzuki
   650 North A'ohoku Place, Hilo, HI 96720, U.S.A
   +1-808-934-5957(tel) / +1-808-934-5984(fax)

   Koji Omata
   650 North A'ohoku Place, Hilo, HI 96720, U.S.A
   +1-808-934-5093(tel) / +1-808-934-5984(fax)

   Tetsuo Nishimura
   650 North A'ohoku Place, Hilo, HI 96720, U.S.A.
   +1-808-934-5085(tel) / +1-808-934-5984(fax)

   Presentation Type:
   Poster Presentation

   Keywords:
   Infrared astronomical instrument, near-infrared,
   multi-object spectroscopy, multi-slit mask