Instrument Overview

The FRIDA Project

Instrument Overview

IAC Contribution

IAC Project Team

Science Drivers

Sky coverage with AO with natural or laser guide star

Other NIR instruments

IAC programs on high spatial resolution techniques and atmospheric optics


Database (internal)

FRIDA Concept:

FRIDA (inFRared Imager and Dissector for Adaptive optics) is the first instrument for the Adaptive Optics system of the 10.4 m Gran Telescopio de Canarias GTC
It has two observation modes:

× Near-IR imaging

with three different plate scales:

× Coarse (0.040 arcsec/pixel)
× Mediun (0.020 arcsec/pixel)
× Fine (0.010 arcsec/pixel)

FRIDA is optimized in the 1.1 - 2.4 µm range, in both imaging and integral field mode.

FRIDA Summary:

Operation modes Imaging and Integral field spectroscopy
Working Wavelength    0.9 - 2.5 µm   (optimized 1.1 - 2.4 µm)   
Detector Hawaii RG 2048x2048 pix
Location Nasmyth platform, at the output focus of GTC Adaprive Optics system
Imaging mode
Scales 0.010 arcsec/pixel
0.020 arcsec/pixel
0.040 arcsec/pixel
FoV ~20x20 arcsec2
~40x40 arcsec2
 Integral field mode
Format 30 slices with 66 pixels/slice in the spatial direction and 2 pixels per resolution element in the spectral direction. The format Nyquist samples both spatial and spectral direction.
Slice Scales
(spectral direction X spatial direction)
0.020 x 0.010 arcsec per slice X arcsec per pixel
0.040 x 0.020 
arcsec per slice X arcsec per pixel
0.080 x 0.040 
arcsec per slice X arcsec per pixel
FoV ~0.60 x 0.66 arcsec2
~1.20 x 1.32 arcsec2
~2.40 x 2.64 arcsec2
Spectral resolution R~ 1300 for the H+K grating
R~ 4000 in  Z, J, H amd bands

R~ 20,000 (goal 30,000) in selectable windows in the 1.4 - 2.4 µm range

FRIDA Observation Modes:

Imaging Mode:

(Image from Marin-Franch, Lenorzer, Herrero & Najarro, 2007)

Integral Field Spectroscopy (IFS):

(Image from Marin-Franch, Lenorzer, Herrero & Najarro, 2007)

Adaptive Optics:

FRIDA will be installed at the Nasmyth A platform behind the output focus of the GTC adaptive optic system (GTCAO.

GTCAO  will routinely deliver subarcsec resolutions down to the GTC diffraction limit, this being about 4 times that provided by HST at the same IR wavelengths.  FRIDA is designed to fully exploit these resolutions in its two observation modes: direct imaging and integral field spectroscopy, both working in the 0.9 -2.5 um range.

Two unique capabilities of FRIDA with respect to current or planned 2D spectrographs are: 1) its high spectral resolution mode, 20,000; 2) its separate imaging mode which will allow the observer very  fast switch to the integral-field-spectroscopy - mode. The combination will allow the user a fast selection of the field of interest for follow up spectroscopy, and facilitate a fast acquisition in the small FoV of the integral field unit.

GTCAO is a Shack-Hartmann-based wave-front sensor working with natural guide stars at optical wavelengths. For a median seeing, 0.65 arcsec,  at the GTC site, it  is expected to provide  an on-axis Strehl ratio of 0.60 in K-band, with guide stars of mR= 6-12,  down to ~ 0.30 for mR = 15. Measurements  of the isoplanatic angle  at La Palma Observatory indicate a degradation of the  Strehl in K-band  to ~10 % when the natural guide star is at 30 arcsec from the science target.

FRIDA Nyquist sample the diffraction limit of GTC in  J-, H- and K-bands in its imaging mode, in K-band  in its integral field mode, and partially in H- and J-bands in the integral field mode.
The integral field mode is provided with  three  spectral resolution sets: ~200 km/s, allowing two atmospheric bands to be observed at  once; ~ 75 km/s, to cover only one band at a time; and  ~15 km/s  to cover selectable regions in the 1.4 -2.5 µm range.

FRIDA design is being optimised in the 1.1 - 2.4 um range,  in both  imaging and integral field mode. Its ultimate performance is foreseen in the K-band where GTCAO is also expected to achieve   maximum atmosphere correction.  In this case,  FRIDA will deliver images and spectra with spatial resolutions close to GTC diffraction limit at 2 um, FWHM ~ 44 mas, with maximized image  contrast  and high throughput for point-like sources

An advantage of FRIDA with respect to akin instruments is that it does not rotate - the rotated field will be provided  by the GTCAO system. This will  translate into  a highly stable instrument with minimum flexure, and an accurately-calibrated distortion pattern.

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