• the collimator is an off-axis parabolic mirror with a diameter of 200 mm and a focal length 7100 mm;
• the echelle mosaic built from two echelle gratings
  (200x250 mm with 37.5 gr mm^-1) has a tan q_b= 2
  (q_b= 63.° 5) blaze angle;
• the echelle mosaic built from three echelle gratings
  (220x320 mm with 37.5 gr mm^-1) has a tan q_b= 6
  (q_b= 80.° 5) blaze angle;
• the cross-disperser is a 45° crown prism;
• the cameras:
  • camera 1 - folded Schmidt ƒ = 450 mm;
  • camera 2 - Schmidt with outer focus ƒ= 875 mm;
  • camera 3 - Schmidt with outer focus ƒ = 1900 mm;
• detectors:
Wright Instruments CCD, 1242x1152 with 22.5 mm pixels

		Mosaic R2		Mosaic R6
Camera (f, mm)	450	875	1900	450
Orders number on CCD	90	90	45	96
Orders length at l 5000 Å (ÅÅ)	70	35	18	26
Linear dispersion at l 5000Å (Å/mm)	2,49	0,33	0,67	0,93
Resolution	43000	80000	180000	120000
Slit width	2"	1"	0,5"	2"