Development of Slewing Mirror Telescope Optical System for the UFFO-pathfinder

¹ Department of Physics, Ewha Womans University, 11-1 Daehyun-dong, Seoul 120-750, Korea
² Department of Physics, National Taiwan University, 1 Roosevelt Road, Taipei, 106, Taiwan
³ Department of Astronomy, Yonsei University, 134 Shinchon-dong, Seoul 120-749, Korea
⁴ Yonsei University Observatory, Yonsei University, 134 Shinchon-dong, Seoul 120-749, Korea
⁵ Department of Physics, Sungkyunkwan University, Seobu-ro, Jangangu, Suwonsi, Gyeongido 440-746, Korea
⁶ National Space Institute Astrophysics, Technical University of Denmark, 2800 Kgs, Lyngby, Denmark
⁷ Instituto de Astrofisica de Andalucia (IAA-CSIC), PO Box 03004, 18080 Granada, Spain
⁸ University of California at Berkeley, Space Sciences Laboratory, 7 Gauss Way, Berkeley, CA 94720, USA
⁹ Department of Energy Engineering, National United University, 1, Lienda, Miaoli, Taiwan, 36003
¹⁰ Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea
¹¹ Institute for the Early Universe, Ewha Womans University, 11-1 Daehyun-dong, Seoul 120-750, Korea
¹² Skobeltsyn Institute of Nuclear Physics of Lomonosov, Moscow State University, Leninskie Gory 119234, Russia
¹³ Universidad de Valencia, GACE, Edif. de Centros de Investigacion, Burjassot, 46100 Valencia, Spain

Abstract

The Slewing Mirror Telescope (SMT) is the UV/optical telescope of UFFO-pathfinder. The SMT optical system is a Ritchey-Chrétien (RC) telescope of 100 mm diameter pointed by means of a gimbal-mounted flat mirror in front of the telescope. The RC telescope has a 17 × 17arcmin² in Field of View and 4.3 arcsec resolution (full width half maximum of the point spread function) The beam-steering mirror enables the SMT to access a 35 × 35degree region and point and settle within 1 sec. All mirrors were fabricated to about 0.02 wavelengths RMS in wave front error (WFE) and 84.7% average reflectivity over 200 nm ~ 650 nm. The RC telescope was aligned to 0.05 wavelengths RMS in WFE (test wavelength 632.8 nm). In this paper, the technical details of the RC telescope and slewing mirror system assembly, integration, and testing are given shortly, and performance tests of the full SMT optical system are reported.