Gemini South Adaptive Optics Imager (GSAOI)

Gemini South Adaptive Optics Imager (GSAOI) on Gemini South.
Gemini South Adaptive Optics Imager (GSAOI) on Gemini South.
Credit: CTIO/NOIRLab/NSF/AURA/D. Munizaga

The Gemini South Adaptive Optics Imager (GSAOI) is a near-infrared adaptive optics imager built by the Research School of Astronomy and Astrophysics (RSAA) of the Australian National University and designed to be used with the Gemini Multi-Conjugate Adaptive Optics System (GeMS) at Gemini South. It can deliver nearly diffraction-limited images in the wavelength interval 0.9–2.5 μm over a 85 x 85-arcsecond field of view. The GSAOI detector is formed of four 2048 x 2048 Rockwell HAWAII-2RG pixel arrays that form a 4080 x 4080-pixel focal plane. There are four gaps of about 2.5 millimeters between the arrays, corresponding to approximately 2.4 arcseconds on sky. Each array has an additional four rows and columns around the outer edges that read out as reference pixels and are not illuminated.

GSAOI contains two filter wheels and one utility wheel.The two filter wheels have 22 broad- and narrow-band (zero-redshifted) emission- and absorption-line filters installed. Each filter wheel also contains one blocked position for recording bias and dark frames. The utility wheel contains a pupil viewer and two defocus lenses (convex and concave). The pupil viewer is used to accurately align the cold stop with GeMS exit pupil viewer and so minimize the background reaching the imager detector. The GSAOI Integration Time Calculator (GSAOI ITC) — a web form in which the user defines the principal aspects of the observation — can be used to determine limiting magnitudes, exposure times, signal-to-noise ratios, background levels, etc. for a wide range of source properties, observing conditions, and GSAOI configurations.

GSAOI internal design graphic.GSAOI internal design graphic.

Science Highlights of GSAOI

Quick Facts

  • In July 2019, the Natural Guide Star Wave Front Sensor (NGS WFS) unit on Canopus was replaced by a new guiding unit called Natural Guide Star Next Generation Sensor (NGS2), resulting in an improvement in sensitivity of about 2.5 magnitudes
  • GSAOI Integration Time Calculator imaging calculations typically take 2–3 seconds 

Gemini South Adaptive Optics Imager (GSAOI)

For scientists: Please find the most up-to-date details about the instrument offerings on the Gemini website.

Site

Cerro Pachón

Telescope

Gemini South

Type

Imager

Wavelength range

0.9–2.4 μm

Spatial sampling

0.02 arcseconds per pixel

Number of detectors

4 Rockwell HAWAII-2RG arrays

(2048 x 2048 pixels each)

Detector format

4 arrays arranged 2 x 2

Detector total size 

4080 x 4080 pixels

Field of view

85 x 85 arcseconds

Filters

Link

Date of first light

16 December 2011 

Science Goals

The science goals are directly related to the Gemini Multi-Conjugate Adaptive Optics System

(GeMS)


Examples include:


The evolution of the mass function of stars in the Milky Way and the Magellanic Clouds


History and evolution of star formation in nearby galaxies


Star formation history of distant galaxies

Images taken with the instruments

Link

Images of the instrument

Link

Videos of the Instrument

Link

Press releases with the instrument

Link