icon Summary of Features


MEGARA (Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía) is an optical integral-field Unit (IFU) and multi-object spectrograph (MOS) designed for the GTC. The MEGARA IFU mode will offer a fibre bundle covering 12.5 arcsec x 11.3 arcsec with a spaxel size of 0.62 arcsec, which makes use of 100 μm-core optical fibers. The MEGARA MOS will allow observing up to 100 objects in a region of 3.5 arcmin x 3.5 arcmin around the IFU bundle. Eight of these bundles will be devoted to the determination of the sky during the observation with the IFU, so only 92 of these positioners will be available for MOS observations. Both the IFU and MOS capabilities of MEGARA will provide intermediate-to-high spectral resolutions (R~6,000, 12,000 and 18,700 respectively for the LR, MR and HR modes).

In the table below we provide a summary of the characteristics of the two MEGARA modes (IFU and MOS) and the corresponding spectral resolutions yield for each set of VPHs.

Spaxel size 0.62 arcsec 0.62 arcsec
Field of View 12.5 x 11.3 arcsec2 3.5 x 3.5 arcmin2
Sampling (1D FWHM) 3.6 pix 3.6 pix
LR VPHs 6,000 6,000
MR VPHs 12,000 12,000
HR VPHs 18,700 18,700

The scientific performance of the complete MEGARA gratings is given in the following table:

VPH ID Setup RFWHM λ12 λC Δλ(@λC) Δv lin res
(Å) (Å) (Å) (km/s) (Å/pix)
VPH405-LR LR-U 6028 3653-4386 4051 0.672 50 0.17
VPH480-LR LR-B 6059 4332-5196 4800 0.792 49 0.20
VPH570-LR LR-V 6080 5143-6164 5695 0.937 49 0.23
VPH675-LR LR-R 6099 6094-7300 6747 1.106 49 0.28
VPH799-LR LR-I 6110 7220-8646 7991 1.308 49 0.33
VPH890-LR LR-Z 6117 8043-9630 8900 1.455 49 0.36
VPH410-MR MR-U 12602 3917-4277 4104 0.326 24 0.08
VPH443-MR MR-UB 12370 4225-4621 4431 0.358 24 0.09
VPH481-MR MR-B 12178 4586-5024 4814 0.395 25 0.10
VPH521-MR MR-G 12035 4963-5443 5213 0.433 25 0.11
VPH567-MR MR-V 11916 5393-5919 5667 0.476 25 0.11
VPH617-MR MR-VR 11825 5869-6447 6170 0.522 25 0.13
VPH656-MR MR-R 11768 6241-6859 6563 0.558 25 0.14
VPH712-MR MR-RI 11707 6764-7437 7115 0.608 26 0.15
VPH777-MR MR-I 11654 7382-8120 7767 0.666 26 0.17
VPH926-MR MR-Z 11638 8800-9686 9262 0.796 26 0.20
VPH665-HR HR-R 18700 6445-6837 6646 0.355 16 0.09
VPH863-HR HR-I 18701 8372-8882 8634 0.462 16 0.12

Figure below shows the distribution of the VPHs in the resolving power versus wavelength coverage plane for all MEGARA VPHs in the case of the 100 μm-core fibers (LCB IFU and MOS modes).


Coverage of the MEGARA VPHs in resolving power (RFWHM) and wavelength for the LCB IFU and MOS modes (100 μm-core fibers).

The scientific interests of the MEGARA Science Team can be grouped in two categories:

  • 1. the study of Galactic and extragalactic nebulae.
  • 2. the study of (or close to) point-sources with intermediate-to-high surface densities.

Among the former their interests include the study of nearby galaxies, Planetary Nebulae and the emission of the resonant UV lines from the high-redshift IGM and among the latter the study of Galactic open stellar clusters, stellar populations in Local Group galaxies, GC systems in nearby galaxies, intermediate-redshift dwarf and starburst galaxies, and high-redshift galaxy clusters are the main subject of their research activities.

Back to top

icon Latest News

icon August 2017
Subject: MEGARA commissioning completed

On August 31st, the last commissioning run for MEGARA was completed successfully. Instrument is being prepared for the routinely operation at GTC and will be offered to the community on early 2018.


Image of both components of MEGARA (focal plane interface and spectrograph) sharing focus with EMIR at GTC Nasmyth-A platform.


Back to top

icon July 2017
Subject: MEGARA First Light

On July 24th took place the official first light of the MEGARA instrument at GTC with the presence of the authorities. Expectations finally got fulfilled with emblematic and spectacular targets to rejoice of those present.



Upper:2D reconstruction of the IFU spectra collected by MEGARA LCB in the M1-92 sky region (different colours represent different ionisation structures). Lower: P-Cygni profiles and bow-shocks in pre-Planetary Nebula M1-92.


Back to top

icon June 2017
Subject: MEGARA commissioning starts

With the instrument integrated in the telescope, works on commissioning test have already started. Thirty nights will be devoted to undertake the complete set of tests designed and planned by the MEGARA team, agreed and approved by the GTC team.


Gas clouds in the light of sight of a QSO that shone when the Universe had 13% its current age.

One of the challenging tests programmed is to reach the spectroscopic limit of the system going as far as MEGARA@GTC can go.

Back to top

icon April 2017
Subject: MEGARA integration

Instrument integration already started at GTC. The first step has been the installation of the optical bench, which occupies most of the available space at Nasmyth A, shared with EMIR instrument (blue box on the right).

MEGARA team, from UCM (Universidad Complutense de Madrid) and FRACTAL SLNE, as well as GRANTECAN personnel are working hard together to get this part of MEGARA ready soon.


The Optical bench been raised up to the Nasmyth platform.


Hoisting process of MEGARA optical bench.


Each step has been carefully planned long time ago, hence the working speed is high. The grism wheel has been already installed (bottom right).


Placing the collimator at its final position.


Back to top

icon March 2017
Subject: MEGARA arrives to the ORM

Welcome MEGARA!! On March 28th MEGARA just arrived to the GTC facilities at the ORM (Observatorio del Roque de los Muchachos).

Two trucks carrying the packages corresponding to the parts of the whole instrument parked in front of the main entrance. And then one entire day is devoted to download the packages, and to get them into the GTC store with the needed attentions.

Trucks Download_pack

After a careful procedure the first package can be seen lying in front of the entrance.


The work just began! During next week and after Easter, mounting process would take place and basic tests should be performed on cabinets.


Detail of the entering process. Special attention to avoid vibrations!


Back to top

icon Feb 2017
Subject: MEGARA starts its journey

MEGARA started these first months of the present year 2017, a long trip toward the scientific operation. During February a thorough process for lab approval took place in Madrid.

It is expected to undertake MEGARA commissioning at the GTC on next summer.


A picture of the setup during the visit of GRANTECAN team to the UCM facilities (LICA lab).


Back to top

icon May 2014
Subject: Green light for MEGARA

The contract for the final development of MEGARA was signed early this month with the Complutense University of Madrid who lead the MEGARA Consortium. Then, the MEGARA further development has green light.

The MEGARA final optical design was completed along 2013 and now the final design of the full instrument is scheduled mid this year.

The current schedule expect to install MEGARA at the GTC by the end of 2016 and to complete its commissioning early 2017.


A 3D drawing of the two main elements of MEGARA installed at the GTC, the focal unit in a folded-cass station and the spectrograph in a nasmyth platform, both conected by the fibre bundle.


Back to top

icon May 2013
Subject: MEGARA Optics Critical Design Review

The MEGARA project has passed its Optics Critical Design Review. This is a critical step for the project as it allows the purchase of the blanks of the optical elements and the manufacture of the MEGARA spectrograph.


Optical layout of MEGARA


Back to top

icon January 2013
Subject: MEGARA completes its Preliminary Design

The formal review of the preliminary designs of the MEGARA instrument was held in March 2012. The outcome was overall positive, although a number of issues required further study. This final step was taken in September, which successfully completed the preliminary design stage. The review process helped clarify and delimit the scope of the project, such as the construction of just a single spectrograph, which is expected to be located on one of the Nasmyth platforms.

Since that time GRANTECAN and the project team have been defining the contractual details for the next steps of the instrument. The detailed optical designs are already under way and are expected to be completed shortly.


A 3D drawing of the spectrograph layout on the optical bench. The large circular platform holds the dispersive elements. The spectrograph slit, collimator and camera is shown at the bottom-left.


Back to top

icon July 2011
Subject: Kick-off for the MEGARA instrument

On July 12 at the GRANTECAN offices in Breña Baja the kick-off meeting for the MEGARA instrument was held, marking the start of the design and construction of a new common-user instrument for the GTC.

MEGARA will be one of the third-generation instruments for the telescope and is led by Dr Armando Gil de Paz from the Universidad Complutense de Madrid. The instrument will combine the very large light gathering power of the telescope with the massive multiplexing capability of the instrument. This combination will open up new and important scientific opportunities. The science team that has defined the capabilities of the instrument foresees the use of MEGARA for a wide range of projects, such as the detailed study of the velocities and chemical composition of nearby galaxies and of the stars and stellar groups within them, studies of the kinematics of Planetary Nebulae, dark matter in dwarf elliptical galaxies, and the study of star formation in intermediate-redshift galaxies as well as studies of the integrated light of clusters of galaxies at very high redshifts.

The instrument will consist of an integral-field fibre unit with two bundles (SCB & LCB) covering the central part of the available field. The perimeter of the field will be filled with a network of fibres that each can be positioned on a specific object. The fibre unit will be mounted in the folded-Cassegrain focal station. The fibres will then translate the light to a dedicated spectrograph that will sit close to one of the Nasmyth platforms. The spectrograph will cover spectral resolutions from R ∼ 6000 to 25000 in the optical wavelength range.

Although the kick-off meeting marks the formal start of the project, it is worth emphasizing that the MEGARA team have already invested a very large amount of time in preparing for this project, which gives MEGARA a flying start and an excellent outlook for the future.


A detail of the MEGARA conceptual design, on the left showing the focal plane layout the with central fibre integral field unit and the robot-driven grid of fibre bundles. On the right is shown how the fibre unit will be attached to the folded Cassegrain acquisition and guiding unit.


Back to top

icon MEGARA contact persons at GTC


contact email @
Daniel Reverte - main contact daniel.reverte
Riccardo Scarpa riccardo.scarpa
Gianluca Lombardi gianluca.lombardi

Back to top

icon More Information:

Back to top


Last modified: 29 September 2017