SOAR Technical Specs

Table with optical data for telescope and various instruments

The Enclosure

  • Achieves precise heat control by means of forced ventilation through a small dome area, set above a small building.
  • Unusually enclosed design promotes highly accurate telescope tracking through its control of wind buffeting.
  • The building was designed in the US and constructed by local Chilean contractors.
  • The dome was built in Brazil, using fiberglass panels from a US firm.

The mount and drives

  • Built by Vertex-RSI Corp. in Texas
  • Uses rolling element bearings for both altitude and azimuth
  • Achieves high pointing and tracking specs
  • Nominal telescope elevation limits: max = 88.5 deg;  min=15 deg (we recommend working at elevations >20 deg. The ADC in the optical ISB can achieve 100% correction only down to 30 deg elevation. Below that, the correction will be only partial). Additional information on the current telescope elevation limits can be found here


  • Ritchey-Chrétien design, f/16.63
  • 4.1m primary mirror made of Corning ULE glass
  • Very high optical quality: 17 nm rms surface.
  • Low thermal mass
  • Primary mirror is 100mm inches thick
  • Plate scale 0.330mm/arcsec or 3.025arcsec/mm
  • Unobstructed field of view: 10 arcmin
  • M1 curvature radius at vertex: -13.50970m
  • M1 conic constant: -1.002667
  • M2 diameter: 0.615m. Corning ULE glass
  • M2 curvature radius: -2.03265m
  • M1-M2 distance: 5.83922m
  • M2-M3 distance: 4.98922m
  • M3 to focus: 4250.0m
  • Effective focal length: 68.175m (F/16.63)
  • Focal surface radius: 0.9656m (convex outside)
  • Central obscuration: 0.228 (diameter 936.5mm)

Active optics system

  • 120-actuator control of primary
  • Secondary on active hexapod
  • Image analyzer permanently mounted at one instrument port.

Tip-tilt tertiary mirror

  • Rapid tip-tilt correction at all foci

Most instruments are permanently mounted:

  • 2 Nasmyth clusters, 3 instruments each
  • 3 Folded-cassegrain foci
  • Rapid selection between instruments: ~60 seconds to switch
  • At least two instruments are always ready, if requested beforehand

Visitor Instruments
If you have an interest in proposing to bring a visitor instrument, please contact the observatory directly beforehand. Waiting until the TAC process starts may be too late! General policies for visitor instruments are described here. A drawing of the Nasmyth instrument mounting locations is here; at present only the IR Nasmyth "straight port" is easily available for small visiting instruments.

Updated on July 5, 2022, 1:50 pm