ALTAIR | Gemini Observatory

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ALTAIR (ALTtitude conjugate Adaptive optics for the InfraRed) is the facility natural/laser guide star adaptive optics system of the Gemini North telescope. It can feed a corrected beam to Gemini instruments NIRI and NIFS. Deploying ALTAIR is "transparent" for the science instrument, as it reproduces the telescope focal ratio (f/16), pupil size and pupil position. ALTAIR is usable in the 1 - 2.5 micron range, with best results achieved in the H and K bands. L- and M-band performance is poor because of the low (~15%) transmittance of the ALTAIR optics in those bands and the greatly increased thermal background.

ALTAIR uses a 177 actuator deformable mirror (DM) and a separate tip-tilt mirror (TTM) to correct for image blurring and distortion caused by atmospheric turbulence. It is equipped with a Shack-Hartmann wave-front sensor (WFS) that uses the visible light to measure the turbulent incident wavefront. The correction is done at a rate of up to 1 kHz (one DM/TTM update every milli-second), and is optimized automatically. ALTAIR was built by the Herzberg Institute of Astrophysics (HIA), Canada.

ALTAIR Natural Guide Star (NGS) function has been offered since 2004A. In 2007A, the ALTAIR Laser Guide Star (LGS) commissioning was completed.

The Instrument Scientist for ALTAIR is Laure Catala, assisted by Marie Lemoine-Busserolle and Andy Stephens.


ALTAIR is currently not available. See the Status and Availability pages for more details.

Altair Science Highlights

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How to Use These Pages

The ALTAIR pages are organized as follows:

  • Status and Availability: Modes available in the current and upcoming semesters; links to news items.
  • Use with NGS: Description of ALTAIR's natural guide star mode and guidance on how best to use the instrument in this mode.
  • Use with LGS: Information about ALTAIR's laser guide star mode and guidance on how best to use the instrument in this mode.
  • Use with LGS+P1: Our newest mode which offers "super-seeing" corrections for any target visible from Gemini North.
  • Field Lens Option: Pros and Cons of using ALTAIR's field lens.
  • Sensitivity and Overheads: Sensitivity tables, integration time calculator, and details of observing overheads.
  • Observation Preparation: How to configure NIRI in the Observing Tool.
  • Image Library: Sample of images in different filters and observing conditions.
  • Documents: ALTAIR design documents and references.


ALTAIR's Laser Guide Star System in operation. Click to view larger image.

ALTAIR Alignment

ALTAIR alignment. Click to view larger image.

Gemini Observatory Participants