Instrumentation developments for GTC



icon Summary


A defining aspect of the scientific success of any telescope installation is its ability to deliver cutting-edge data through novel instrumentation. An exciting and extensive instrumentation development program exists for GTC. The telescope can currently host up to two instruments for its Nasmyth foci. three instruments at the Folded-Cassegrain foci, and one instrument also in the main Cassegrain focus.

In order to maximise the scientific return from the GTC, telescope is prepared to accept visitor instruments as they can bring additional capabilities to the GTC not available with the suite of facility instruments. The procedures for proposing a Visitor Instrument to the GTC, and the rationale for visiting instruments are explained in this document.

Also, of interest for any possible instrument developer, the discussion on the general roules for the distribution of Guaranteed time, both for facility instruments and visitor instruments, are described here.

On this table a summary of present and future GTC instrumentation is given (instruments available for the ongoing semester are highlighted in green, while instruments decomissioned are highlighted in grey).

and focus
Status Main features
0.36 - 1 Common-user instrument.
Operational since 2009.
Operative in Cassegrain since July 2022.
Upgraded to OSIRIS+(with a new blue sensitive monolithic detector) in early 2023.
7.8 x 7.8 arcmin field.
Broad- medium- and narrow-band imaging.
Tunable filter imaging.
Fast photometry capabilities.
Long-slit and multi-object spectroscopy.
Spectral resolutions 300 to 2500.
Folded Cass-E
8 - 25 Common-user instrument.
Operational from 2012 to 2016.
Decomissioned in April 2016. Back to the telescope in Folded Cass-E station from mid-2019 to late-2020, sharing this focal station with HIPERCAM. Finally decomissioned in February 2021.
26 x 19 arcsec field.
Imaging and long-slit spectroscopy.
Spectral resolutions 175 to 1300.
Imaging and spectral polarimetry.
Folded Cass-E
1 - 2.5 Visitor instrument (University of Florida).
Operational since September 2015.
Decomissioned in September 2017.
3.4 x 3.4 arcmin field.
Imaging and polarimetry.
1 - 2.5 Common-user instrument.
Operational since 2017.
Upgraded with a new H2RG detector in early 2024.
6.67 x 6.67 arcmin field (imaging).
4 x 6.67 arcmin field (spectroscopy).
Broad- and narrow-band imaging.
Long-slit and multi-object spectroscopy through configurable cold slits.
Spectral resolutions 1000/4000-5000.
Fed from OSIRIS
0.4 - 0.7 Visitor instrument (IAC).
Operational since 2019.
Decomissioned in August 2021.
Point-source fiber spectroscopy.
High spectral stability.
Spectral resolution 25000
Folded Cass-G
0.36 - 1 Visitor instrument (IAC, University of Sheffield).
Operational from February 2018 to September 2019, and back to the telescope from April 2021 to September 2021 at Folded Cass-E.
Installed permanently at
Folded Cass-G from May 2023.
High-speed, multi-band imager.
2.8 x 1.4 arcmin field of view.
Folded Cass-F
0.4 - 1 Common-user instrument.
Operational since 2018.
3.5 x 3.5 arcmin field (MOS mode) and 12.5 x 11.3 arcsec (IFU mode).
fibre spectroscopy
Up to 100 objects simultaneous through positionable fibres.
Spectral resolution 5500 to 20000.
Folded Cass-E
1 - 2.5 Common-user instrument.
Installed in mid-2022.
Operational late-2024.
Up to 12 targets via deployable probe arms, each feeding a 3.7 x 1.2 arcsec field of view.
Multi-object spectroscopy with up to 12 objects.
Spectral resolution 20000.
1 - 2.5 Common-user instrument.
Installed in mid-2023 (GTCAO). Operational mid-2025 (GTCAO+FRIDA).
Imaging and integral-field spectroscopy.
Spectral resolution 1500 to 30000.
Diffraction limited performance in combination with the GTC adaptive optics unit. Imaging (FoV 20x20 or 40x40 arcsec) and integral field spectroscopy (FoV up to 2.6 x 2.4 arcsec).
+ Coudé
0.31 - 0.78 Common-user instrument.
To be installed in 2027.
Φ 1.2" aperture High Resolution Spectrograph.
Two different arms with Spectral Resolutions of 25000 (UVS) and 110000 (VIS).

Current timeline for GTC instruments in the period 2019-2025.


GTC instruments evolution (2009-2027).

Back to top

icon Day-One instruments


The first two instruments were delivered to GTC to populate the Nasmyth-A and -B focal stations. The very first instrument for scientific use was OSIRIS, which started operation when the telescope commenced its scientific life, in March 2009. OSIRIS works in the optical wavelength range and can be used for high-quality imaging and longs-slit as well as multi-object spectroscopy. The arrival of GTCAO by mid-2023 at the Nasmyth-B focal station moved OSIRIS to Cassegrain focus some time before, in mid-2022. A new monolithic blue sensitive detector was installed in OSIRIS in late 2022, enhancing the instrument sensitivity (OSIRIS+).

The second instrument CanariCam came on-line in 2012, after a long period of preparing the telescope for it (in particular the chopping motion of the secondary mirror and achieving getting the primary mirror segments in phase). CanariCam is a thermal infrared camera and spectrograph with polarimetry and coronography capabilities. CanariCam was in operation up to April 2016, when it was removed from the Nasmyth A focus to be placed in one of the Folded Cass focal stations later, or share it with another instrument. After a productive period of operation at Folded Cass-E between 2019 and 2020, CanariCam was finally decommissioned in February 2021.

These first two instruments have been developed by consortia formed by several research centers. The consortium that developed OSIRIS was led by the Instituto de Astrofísica de Canarias (IAC), with the participation of the IA-UNAM, IFCA and IAA. CanariCam was built by the University of Florida.

Back to top

icon Visitor instruments


In December 2014 we received and installed the first visitor instrument, CIRCE, from the University of Florida. This instrument, designed and built on initiative by Prof. Eikenberry, was commissioned along 2015 and will deliver important near-IR imaging capability to the telescope. The instrument may be upgraded for spectroscopy. Although being formally a visiting instrument, it was made available to the general community since September 2015 for two years, being finally decommissioned in September 2017.

By the end of 2017, HiPERCAM instrument was received at GTC and operations started since early 2018. This instrument is a high-speed camera for the study of rapid variability in the Universe. It will be able to image simultaneously in 5 optical channels - u' g' r' i' z' - at rates of over 1000 frames per second. As the only 8-10 m-class telescope in the world with such a facility, the GTC would become the world-leader in follow-up studies of variable and transient sources. The instrument was available at Folded Cass-E in a short operational window from April 2021 to September 2021, and it was finally installed permanently in Folded Cass-G focal station from May 2023, using an specific rotator for this instrument.

A third visiting instrument, HORuS, has been developed at the IAC (PI: Dr. Carlos Allende Prieto) and it was commissioned along 2017-2018. HORuS started operations in July 2019. This instrument delivers high-resolution spectra of point sources in the optical wavelength range. HORuS was in operation until the migration of OSIRIS to Cassegrain in August 2021, when it was decommissioned. A possible future use of HORuS at Nasmyth-B platform (without OSIRIS) is currently under discussion.

Back to top

icon Second generation instruments


The next common-user instrument that was built for the GTC is EMIR, a multi-object spectrograph and imager for the near infrared. With its cryogenic configurable slit unit and medium spectral resolution this instrument is expected to become one of the work-horse instruments. EMIR was developed by a consortium led by the IAC and arrived at the telescope in 2016 for its on-sky commissioning, starting the regular operations on mid-2017. In order to solve the lack of sensitivity experienced by the instrument, a new H2RG sensitive detector was installed in EMIR in late 2023.

FRIDA is another instrument for GTC that is being developed. FRIDA, will make use of the GTC Adaptive Optics system, being able to take pictures in broad-band and narrow-band filters, as well as facilitate integral-field spectroscopy in the spectral range of 0.9 - 2.5 μm. FRIDA is a project led by the Instituto de Astronomía de la Universidad Nacional Autónoma de México (UNAM) in partnership with the Instituto de Astrofísica de Canarias (IAC), the University of Florida (UF), and the Universidad Complutense de Madrid (UCM). The instrument is in its phase of construction and is scheduled to arrive at the telescope by late-2024, to begin the regular operations by mid-2025.

Back to top

icon Third generation instruments


Development of instrumentation is a long process and hence for its planning one must look several years into the future. In order to help define the progression needed to keep GTC scientifically competitive throughout the decade ahead of the year 2008, an independent panel was tasked with analyzing GTC´s future instrumentation needs. Recommendations provided by this work panel can be found here.

Based on the outcome of this study, it was decided to proceed with the development of two medium-dispersion spectrographs, one in the visible range and another in the near infrared, to be implemented in the telescope around 2016-2017.

After a competitive process, in late 2010 the MEGARA and MIRADAS instruments were selected to proceed.

MEGARA successfully completed its commissioning on August 2017, starting the regular operations in mid-2018.

MIRADAS was installed in the GTC in mid-2022, with the aim of starting the regular operations by late-2024 (due to some delays in the refurbishment of some particular optical components).

In 2013 a new independent panel was tasked with review the instrumentation plans at the GTC and to advice on priorities. Recommendations provided by this work panel can be found here.

Back to top



Canary Hybrid Optical high-Resolution Ultra-stable Spectrograph (CHORUS) is the high resolution spectrograph developed by National Observatories of Chinese Academy of Sciences (NAOC-NIAOT) within the framework of the Collaboration Agreement between the GTC and the National Astronomical Observatories of China signed in 2016.

The instrument will provide high resolution spectra by using a two-arm spectrograph, with a UV-module (R>25,000) placed below Nasmyth-B platform and a visible spectrograph (R>110,000) located at Coudé room. According to the Conceptual Design, the main characteristics of the instrument are summarized in the Table below:


Subsystems UV band Spectrograph (UVS) Visible band Spectrograph (VIS)
Location Below Nasmyth Platform B Coudé room
Fiber configuration Φ 1.2" aperture on the sky Φ 1.2" aperture on the sky
Spectral resolution R ≥ 25,000 R ≥ 110,000
Wavelength coverage 310 - 420 nm 420 - 780 nm
Wavelength calibration precision --- ∼ 10 cm/s with LFC
Calibration Ordinary single fiber calibration Sim.-Calibration, Sky subtraction
Instrument daily stability --- Inside Instrument Vacuum Chamber
at ∼ 16 °C (±2 °C) ±0.001 °C /night.
Operation pressure
in IVC ≤ 0.001 mbar
Instrument efficiency
(from input fiber to
detector front)
≥ 17% at peak,
≥ 5% at minimum
≥ 17% at peak,
≥ 8% at minimum


Funding for CHORUS have been officially approved by Chinese Academy of Sciences in 2022, and the Preliminary Design Reviwew was held in September 2023. Current schedule shows the installation of CHORUS by 2027.

Back to top

icon Next generation instruments (2030+)


As described above, present instrumentation plan at the GTC will be completed around 2025. At that time, six or seven science instruments will fill the large suite of focal stations of the GTC, so they should guarantee the scientific competitiveness of the telescope for several years to come, also considering that the GTC will continue to be the largest optical telescope in operation. Even so, it is time to think about the future. Defining and building new instruments is a complex process that takes a minimum of five years. This puts us to around 2030, when the new generation of extremely large telescopes will presumably start operation.

On this regard, GRANTECAN has opened a process to define the next generation of GTC instruments. Details on this call and current proposed instruments can be found here.

Back to top


Last modified: 15 March 2024

Utilizamos cookies propias y de terceros para fines analíticos y para mostrarte publicidad personalizada en base a un perfil elaborado a partir de tus hábitos de navegación (por ejemplo, páginas visitadas). Puedes configurar o rechazar la utilización de cookies u obtener más información en nuestra Politica de Cookies. Acepto Rechazar