MEGARA

 

 


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.

IFU MOS
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).

MegaraVPHs

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.

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icon Latest News

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.

spectrograph

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.

 

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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.

spectrograph

Optical layout of MEGARA

 

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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.

spectrograph

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.

 

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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.

megara

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.

 

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icon MEGARA contact persons at GTC

 

contact email @ gtc.iac.es
Daniel Reverte - main contact daniel.reverte
Riccardo Scarpa riccardo.scarpa

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Last modified: 02 December 2016