Telescope

Owned by Kazuya Matsubayashi
Last updated: Aug 01, 2024
2 min read

 

Optics

  • Primary mirror: a monolithic 6500-mm diameter concave mirror

  • Secondary mirror: a monolithic 897-mm diameter convex mirror

  • Effective diameter of the primary mirror: 6153.6 mm

  • Effective focal length: 75074 mm

  • Focal ratio: F/12.2

  • Plate scale: 2.75 arcsec/mm

  • Focus: 2 Nasmyth and 2 bent-Cassegrain foci

  • Pupil position: at the secondary mirror

  • Image quality (80% encircled energy diameter): 0.39 arcsec

Drive system

  • Mount: an altazimuth system

  • Range of movement: 22-89 degrees for altitude, 360 degrees (+-270 degrees) for azimuth

  • Maximum rotation speed: 2 degrees per second for altitude and azimuth

  • Pointing accuracy: 2 arcsec in RMS

  • Tracking accuracy: 0.2 arcsec in RMS radius for 10 minutes in open tracking at the wind speed of less than 15 m/s

  • Required time in tertiary mirror rotation: about 2 minutes in a 180-degree rotation

Auxiliary Component

Instrument Rotator

  • rotates observational instruments and auxiliary components for canceling out the rotation of the field of view

  • one rotator for each Nasmyth focus

  • Components: an instrument, a Shack-Hartmann wavefront sensor, and an auto guider camera

  • Maximum rotation speed: 3 degrees per second

Shack-Hartmann wavefront sensor

  • always activates during the observations to detect errors in the primary mirror shape

  • Limiting magnitude for guide stars: 16.0 mag in V-band for NICE and SWIMS, or 14.2 mag in I-band for MIMIZUKU

Auto Guider Camera

  • for correcting the telescope tracking errors

  • non-mandatory in observations if the tracking error is acceptable

  • Field of view: 16.6 x 12.2 arcsec for NICE and SWIMS, and 41 x 55 arcsec MIMIZUKU

  • Movable area: 10 arcmin radius from the telescope optical axis

  • Limiting magnitude for NICE and SWIMS: 16.0 mag, 15.2 mag, and 14.5 mag in V-, R-, and I-band, respectively, in a 10-second exposure

  • Limiting magnitude for MIMZUKU: 14.5 mag in I-band in a 10-second exposure at 0.6 arcsec seeing

  • Tracking accuracy with feedback: 0.15 times seeing