- Email: [email protected]
FRIDA: The infrared imager and integral field spectrograph for the adaptive optics system of GTC
New Astronomy Reviews 50 (2006) 389–391 www.elsevier.com/locate/newastrev
FRIDA: The infrared imager and integral field spectrograph for the adaptive optics system of GTC q S. Cuevas a,*, J.A. Lo´pez b,1, S. Eikenberry c, B. Sa´nchez a, A. Watson d, F. Garzo´n f, A. Prieto f,g, J. Fuentes a,2, J.J. Dı´az f, C. Espejo a, R. Flores a, V. Bringas e, O. Chapa a
a
Instituto de Astronomı´a, UNAM, Circuito Exterior, Ciudad Universitaria, P.O. Box 70-264, 04510 Ciudad, Mexico b Instituto de Astronomı´a, UNAM, Ensenada, Mexico c Department of Astronomy, University of Florida, USA d Centro de Radioastronomı´a y Astrofı´sica, UNAM, Morelia, Mexico e Centro de Ingenierı´a y Desarrollo Industrial, Quere´taro, Mexico f Instituto de Astrofı´sica de Canarias, Spain g MPIA, Heildelberg, Germany Available online 19 April 2006
Abstract FRIDA has been conceived as the first science instrument for the adaptive optics system of the Gran Telescopio Canarias (GTC). It is designed to be installed at the Nasmyth A platform, behind the GTC adaptive optics system. FRIDA will be a diffraction limited, near infrared imager and integral field spectrograph sensitive from 0.9 to 2.5 lm. It may also include provisions for future upgrades such as coronographic masks and long slits. FRIDA is a collaborative project between the Instituto de Astronomı´a, UNAM, Me´xico, the Instituto de Astrofı´sica de Canarias, Spain, and the Astronomy Department of the University of Florida, USA. 2006 Elsevier B.V. All rights reserved. Keywords: Infrared instruments; Near infrared; Spectroscopy and spectrophotometry; Image reconstruction
Contents 1. 2. 3. 4.
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Introduction . . . . . . . . . . Imaging . . . . . . . . . . . . . Integral field spectroscopy Performance . . . . . . . . . . Acknowledgments . . . . . . References. . . . . . . . . . . .
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Gran Telescopio Canarias. Corresponding author. Tel.: +52 55 56 22 39 35; fax: +52 55 56 16 06
1. Introduction
E-mail address: [email protected] (S. Cuevas). Principal investigator. On sabbatical leave from IAC.
FRIDA will be a diffraction-limited near infrared imager and integral field spectrograph and will cover the wavelength range from 0.9 to 2.5 lm with the use of a single
23. 1
. . . . . .
1387-6473/$ - see front matter 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.newar.2006.02.025
390
S. Cuevas et al. / New Astronomy Reviews 50 (2006) 389–391
Focal Plane: field masks Lyot spots
Pre Optics Collimator
Grating Spectrograph
Pre Optics Camera window Pupil Plane: filters rotating Lyot stop
I F U
Hawaii 2Kx2K
Fig. 1. Basic FRIDA layout. The pre-optics collimator and camera are CaF2 and FTM16 doublets. The spectrograph performs as a 1:1 imager replacing the diffraction grating by a mirror. The spatial scale is selected changing the pre-optics camera.
Table 1 Summary of main parameters for FRIDA Working location Wavelength range Observing modes Array format
Nasmyth A platform, after GTC AO system 0.9–2.5 lm, performance optimized for 1.1–2.4 lm Imaging and Integral Field Spectroscopy 2048 · 2048 HgCdTe Hawaii 2, Rockwell
Imaging mode scales Field of view
0.012 and 0.020 arcsec pixel 1 24.6 · 24.6 and 41.0 · 41.0 arcsec
IFS mode scales
0.012 arcsec pixel 1 · 0.036 arcsec slice 0.020 arcsec pixel 1 · 0.060 arcsec slice 0.65 · 1.30 and 1.1 · 2.2 arcsec R 500, 5000 and 30,000
Field of view Spectral resolutions
the GTC adaptive optics system (Devaney et al., 2004) enters from the left through the dewar window. The optics form a dual re-imaging system. The spatial scale is selected by changing the pre-optics. 2. Imaging
1 1
2048 · 2048 Hawaii 2 Rockwell detector. The same detector will be used for the imaging and IFS modes. The basic optical scheme of FRIDA is shown in Fig. 1. Light from
FRIDA will provide a direct imaging mode with broad-band and narrow-band filters, selectable spatial scales of 0.012 and 0.020 arcsec pixel 1 and corresponding fields of view of 24.6 · 24.6 and 41.0 · 41.0 arcsec. The finer scale will provide adequate sampling of the almost diffraction limited core in J and H bands and the coarser scale will provide adequate sampling in K (see Table 1).
Fig. 2. The model for the FRIDA Integral Field Spectrograph is being designed with the Zemax Non Sequential Components mode, based on FISICA, as shown here.
S. Cuevas et al. / New Astronomy Reviews 50 (2006) 389–391
3. Integral field spectroscopy FRIDA will also provide an integral field spectroscopy mode using an image slicer. The IFU design is based on FISICA (Eikenberry et al., 2004), see Fig. 2. The selectable spatial scales parallel to the slices will be 0.012 and 0.020 arcsec pixel 1 and the corresponding spatial scales perpendicular to the slices will be 0.036 and 0.060 arcsec slice 1. Each slice will project to two pixels in the spectral direction. For an image slicer with 18 slices, these scales yield fields of view of 0.65 · 1.3 and 1.1 · 2.2 arcsec. The available spectral resolutions will be R 500, 5000 and 30,000. 4. Performance The expected sensitivity of FRIDA has been modelled for imaging and spectroscopy of point and resolved sources with continuum and emission line spectra. The figure of merit for imaging or spectroscopy is the magnitude at which a signal-to-noise ratio of 10 per resolution element is reached in the core. The 1 h limiting magnitudes for a signal-to-noise ratio of 10 in direct imaging of point sources are 25.5 in Z, 25.1 in J, 24.1 in H and 22.8 in Ks.
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The corresponding limiting magnitudes per resolution element for resolution 5000 spectroscopy are 20.0 in Z, 19.9 in J, 19.7 in H and 18.6 in K. In summary, FRIDA will provide capabilities for imaging a relatively large field at near the diffraction limit of the GTC and obtaining integral field spectroscopy from low to high spectral resolution. The design can incorporate straightforward upgrade paths for long-slit spectroscopy and focal plane masks. FRIDA is currently in the PDR stage. Acknowledgments We gratefully acknowledge the support from the GTC project office, a grant from Grupo Santander (Spain) through Encuentros Astrofı´sicos Blas Cabrera (UNAMIAC) and our home institutions, UNAM, IAC and University of Florida for their support. References Devaney, N. et al., 2004. SPIE 5490, 913. Eikenberry, S. et al., 2004. SPIE 5492, 1264.
FRIDA: The infrared imager and integral field spectrograph for the adaptive optics system of GTC q S. Cuevas a,*, J.A. Lo´pez b,1, S. Eikenberry c, B. Sa´nchez a, A. Watson d, F. Garzo´n f, A. Prieto f,g, J. Fuentes a,2, J.J. Dı´az f, C. Espejo a, R. Flores a, V. Bringas e, O. Chapa a
a
Instituto de Astronomı´a, UNAM, Circuito Exterior, Ciudad Universitaria, P.O. Box 70-264, 04510 Ciudad, Mexico b Instituto de Astronomı´a, UNAM, Ensenada, Mexico c Department of Astronomy, University of Florida, USA d Centro de Radioastronomı´a y Astrofı´sica, UNAM, Morelia, Mexico e Centro de Ingenierı´a y Desarrollo Industrial, Quere´taro, Mexico f Instituto de Astrofı´sica de Canarias, Spain g MPIA, Heildelberg, Germany Available online 19 April 2006
Abstract FRIDA has been conceived as the first science instrument for the adaptive optics system of the Gran Telescopio Canarias (GTC). It is designed to be installed at the Nasmyth A platform, behind the GTC adaptive optics system. FRIDA will be a diffraction limited, near infrared imager and integral field spectrograph sensitive from 0.9 to 2.5 lm. It may also include provisions for future upgrades such as coronographic masks and long slits. FRIDA is a collaborative project between the Instituto de Astronomı´a, UNAM, Me´xico, the Instituto de Astrofı´sica de Canarias, Spain, and the Astronomy Department of the University of Florida, USA. 2006 Elsevier B.V. All rights reserved. Keywords: Infrared instruments; Near infrared; Spectroscopy and spectrophotometry; Image reconstruction
Contents 1. 2. 3. 4.
q *
Introduction . . . . . . . . . . Imaging . . . . . . . . . . . . . Integral field spectroscopy Performance . . . . . . . . . . Acknowledgments . . . . . . References. . . . . . . . . . . .
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389 390 391 391 391 391
Gran Telescopio Canarias. Corresponding author. Tel.: +52 55 56 22 39 35; fax: +52 55 56 16 06
1. Introduction
E-mail address: [email protected] (S. Cuevas). Principal investigator. On sabbatical leave from IAC.
FRIDA will be a diffraction-limited near infrared imager and integral field spectrograph and will cover the wavelength range from 0.9 to 2.5 lm with the use of a single
23. 1
. . . . . .
1387-6473/$ - see front matter 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.newar.2006.02.025
390
S. Cuevas et al. / New Astronomy Reviews 50 (2006) 389–391
Focal Plane: field masks Lyot spots
Pre Optics Collimator
Grating Spectrograph
Pre Optics Camera window Pupil Plane: filters rotating Lyot stop
I F U
Hawaii 2Kx2K
Fig. 1. Basic FRIDA layout. The pre-optics collimator and camera are CaF2 and FTM16 doublets. The spectrograph performs as a 1:1 imager replacing the diffraction grating by a mirror. The spatial scale is selected changing the pre-optics camera.
Table 1 Summary of main parameters for FRIDA Working location Wavelength range Observing modes Array format
Nasmyth A platform, after GTC AO system 0.9–2.5 lm, performance optimized for 1.1–2.4 lm Imaging and Integral Field Spectroscopy 2048 · 2048 HgCdTe Hawaii 2, Rockwell
Imaging mode scales Field of view
0.012 and 0.020 arcsec pixel 1 24.6 · 24.6 and 41.0 · 41.0 arcsec
IFS mode scales
0.012 arcsec pixel 1 · 0.036 arcsec slice 0.020 arcsec pixel 1 · 0.060 arcsec slice 0.65 · 1.30 and 1.1 · 2.2 arcsec R 500, 5000 and 30,000
Field of view Spectral resolutions
the GTC adaptive optics system (Devaney et al., 2004) enters from the left through the dewar window. The optics form a dual re-imaging system. The spatial scale is selected by changing the pre-optics. 2. Imaging
1 1
2048 · 2048 Hawaii 2 Rockwell detector. The same detector will be used for the imaging and IFS modes. The basic optical scheme of FRIDA is shown in Fig. 1. Light from
FRIDA will provide a direct imaging mode with broad-band and narrow-band filters, selectable spatial scales of 0.012 and 0.020 arcsec pixel 1 and corresponding fields of view of 24.6 · 24.6 and 41.0 · 41.0 arcsec. The finer scale will provide adequate sampling of the almost diffraction limited core in J and H bands and the coarser scale will provide adequate sampling in K (see Table 1).
Fig. 2. The model for the FRIDA Integral Field Spectrograph is being designed with the Zemax Non Sequential Components mode, based on FISICA, as shown here.
S. Cuevas et al. / New Astronomy Reviews 50 (2006) 389–391
3. Integral field spectroscopy FRIDA will also provide an integral field spectroscopy mode using an image slicer. The IFU design is based on FISICA (Eikenberry et al., 2004), see Fig. 2. The selectable spatial scales parallel to the slices will be 0.012 and 0.020 arcsec pixel 1 and the corresponding spatial scales perpendicular to the slices will be 0.036 and 0.060 arcsec slice 1. Each slice will project to two pixels in the spectral direction. For an image slicer with 18 slices, these scales yield fields of view of 0.65 · 1.3 and 1.1 · 2.2 arcsec. The available spectral resolutions will be R 500, 5000 and 30,000. 4. Performance The expected sensitivity of FRIDA has been modelled for imaging and spectroscopy of point and resolved sources with continuum and emission line spectra. The figure of merit for imaging or spectroscopy is the magnitude at which a signal-to-noise ratio of 10 per resolution element is reached in the core. The 1 h limiting magnitudes for a signal-to-noise ratio of 10 in direct imaging of point sources are 25.5 in Z, 25.1 in J, 24.1 in H and 22.8 in Ks.
391
The corresponding limiting magnitudes per resolution element for resolution 5000 spectroscopy are 20.0 in Z, 19.9 in J, 19.7 in H and 18.6 in K. In summary, FRIDA will provide capabilities for imaging a relatively large field at near the diffraction limit of the GTC and obtaining integral field spectroscopy from low to high spectral resolution. The design can incorporate straightforward upgrade paths for long-slit spectroscopy and focal plane masks. FRIDA is currently in the PDR stage. Acknowledgments We gratefully acknowledge the support from the GTC project office, a grant from Grupo Santander (Spain) through Encuentros Astrofı´sicos Blas Cabrera (UNAMIAC) and our home institutions, UNAM, IAC and University of Florida for their support. References Devaney, N. et al., 2004. SPIE 5490, 913. Eikenberry, S. et al., 2004. SPIE 5492, 1264.