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|
The scientific performance of the complete MEGARA gratings is given in the following table:
|VPH ID||Setup||RFWHM||λ1-λ2||λC||Δλ(@λC)||Δv||lin res|
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).
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.
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.
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.
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.
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 contact persons at GTC
|contact||email @ gtc.iac.es|
|Daniel Reverte - main contact||daniel.reverte|
Last modified: 02 December 2016