A. Calcines

FastCam: a new lucky imaging instrument for medium-sized telescopes

FastCam is an instrument jointly developed by the Spanish Instituto de Astrofísica de Canarias and the Universidad Politécnica de Cartagena designed to obtain high spatial resolution images in the optical wavelength range from ground-based telescopes. The instrument consists of a very low noise and very fast readout speed EMCCD camera capable of reaching the diffraction limit of medium-sized telescopes from 500 to 850 nm. FastCam incorporates a FPGAs-based device to save and evaluate those images minimally disturbed by atmospheric turbulence in real time. The undisturbed images represent a small fraction of the observations. Therefore, a special software package has been developed to extract, from cubes of tens of thousands of images, those with better quality than a given level. This is done in parallel with the data acquisition at the telescope. After the first tests in the laboratory, FastCam has been successfully tested in three telescopes: the 1.52-meter TCS (Teide Observatory), the 2.5-meter NOT, and the 4.2-meter WHT (Roque de los Muchachos Observatory). The theoretical diffraction limit of each telescope has been reached in the I band (850 nm) -0.15, 0.08 and 0.05 arcsec, respectively-, and similar resolutions have been also obtained in the V and R bands. Future work will include the development of a new instrument for the 10.4-meter GTC telescope on La Palma.

MuSICa: THE MULTI-SLIT IMAGE SLICER FOR THE EST SPECTROGRAPH

Integral field spectroscopy (IFS) is a technique that allows one to obtain the spectra of all the points of a bidimensional field of view simultaneously. It is being applied to the new generation of the largest night-time telescopes but it is also an innovative technique for solar physics. This paper presents the design of a new image slicer, MuSICa (Multi-Slit Image slicer based on collimator-Camera), for the integral field spectrograph of the 4-m aperture European Solar Telescope (EST). MuSICa is a multi-slit image slicer that decomposes an 80 arcsec2 field of view into slices of 50 μm and reorganizes it into eight slits of 0.05 arcsec width × 200 arcsec length. It is a telecentric system with an optical quality at diffraction limit compatible with the two modes of operation of the spectrograph: spectroscopic and spectro-polarimetric. This paper shows the requirements, technical characteristics and layout of MuSICa, as well as other studied design options.

Spectrograph capabilities of the European Solar Telescope

EST is a project for a 4-meter class telescope to be located in the Canary Islands. EST will be optimized for studies of the magnetic coupling between the photosphere and the chromosphere. This requires high spatial and temporal resolution diagnostics tools of properties of the plasma, by using multiple wavelength spectropolarimetry. To achieve these goals, visible and near-IR multi-purpose spectrographs are being designed to be compatible with different modes of use: LsSS (Long-slit Standard Spectrograph), multi-slit multi-wavelength spectrograph with an integral field unit, TUNIS (Tunable Universal Narrow-band Imaging Spectrograph), and new generation MSDP (Multi-channel Subtractive Double-pass Spectrograph). In this contribution, these different instrumental configurations are described.

A high-resolution spectrograph for the solar telescope GREGOR

This communication shows the design, layout, mounting and start-up of a high-resolution grating spectrograph for VIS-NIR at GREGOR 1.5m Solar Telescope (Observatorio del Teide, Tenerife, Canary Islands). The instrument will be used together with the Tenerife Infrared Polarimeter (TIP-II). As special characteristics of the design, the following can be mentioned: The first folding mirror of the spectrograph can be placed in two positions to take into account the change of the optical axis introduced by the polarizing beamsplitter of TIP-II. This way the instrument is optimally aligned when used in situations with and without polarimeter. The second and third mirrors rotate the image of the entrance slit, making it parallel to the grating grooves. A system of prisms are used to adequately fit onto the detector the two orthogonal polarized beams generated by the polarimeter. Two output beams are possible, to make feasible simultaneous visible and near-infrared observations.

MuSICa image slicer prototype at 1.5-m GREGOR solar telescope

Integral Field Spectroscopy is an innovative technique that is being implemented in the state-of-the-art instruments of the largest night-time telescopes, however, it is still a novelty for solar instrumentation. A new concept of image slicer, called MuSICa (Multi-Slit Image slicer based on collimator-Camera), has been designed for the integral field spectrograph of the 4-m European Solar Telescope. This communication presents an image slicer prototype of MuSICa for GRIS, the spectrograph of the 1.5-m GREGOR solar telescope located at the Observatory of El Teide. MuSICa at GRIS reorganizes a 2-D field of view of 24.5 arcsec into a slit of 0.367 arcsec width by 66.76 arcsec length distributed horizontally. It will operate together with the TIP-II polarimeter to offer high resolution integral field spectropolarimetry. It will also have a bidimensional field of view scanning system to cover a field of view up to 1 by 1 arcmin.

Feasibility study of high-resolution integral-field spectrographs for EST with multislit and multi-wavelength capabilities

This communication shows the feasibility study of a new instrument designed for the 4 meter European Solar Telescope (EST) for high resolution spectro-polarimetric observations. This paper is specifically focused on the spectrographs that allow the simultaneous observation of 5 visible and 4 near-infrared wavelengths (complying with the science requirements), with 8 entrance slits of 200arcsec each fed by an integral field unit covering an area on the solar surface of 9 x 9 arcsec2.

The participation of the Instituto de Astrofísica de Canarias in the European Solar Telescope

This communication reviews the participation of the Instituto de Astrofísica de Canarias (IAC) in the design of the European Solar Telescope. Apart of being the coordinator institution of the whole project, and, as such, responsible for the project managing, the IAC leads several tasks like overall instrument definition or characterization of the atmospheric turbulence profile with height or the definition of adequate detectors. More in particular, the IAC will design and build two long-base SHABAR (SHAdow BAnd Ranger), instruments to measure medium-altitude seeing. The IAC is also responsible for the design, together with other institutions, of the design of grating spectropolarimeters suitable for multiwavelength high spatial and spectral resolution.

Preliminary design of a multi-slit image slicer for EST

Integral field spectroscopy is a modern technique used in Astronomy to obtain simultaneous spectral information of all points in a bidimensional field of view. This communication presents the preliminary design of a multi-slit image slicer to be coupled to the spectrographs of the 4 meters aperture European Solar Telescope. This integral field unit will provide the observation of an 80 arcsec2 field of view, rearranged into 8 slits of 200 arcsec length by 0.05 arcsec width. Different optical design alternatives with diffraction limited optical quality, as well as the design of a prototype for the GREGOR solar telescope, are presented.

Feasibility study of an image slicer for future space application

This communication presents the feasibility study of an image slicer for future space missions, especially for the integral field unit (IFU) of the SUVIT (Solar UV-Visible-IR telescope) spectro-polarimeter on board the Japanese-led solar space mission Solar-C as a backup option. The MuSICa (Multi-Slit Image slicer based on collimator-Camera) image slicer concept, originally developed for the European Solar Telescope, has been adapted to the SUVIT requirements. The IFU will reorganizes a 2-D field of view of 10 x 10 arcsec2 into three slits of 0.18 arcsec width by 185.12 arcsec length using flat slicer mirrors of 100 μm width. The layout of MuSICa for Solar-C is telecentric and offers an optical quality limited by diffraction. The entrance for the SUVIT spectro-polarimeter is composed by the three IFU slits and one ordinal long slit to study, using high resolution spectro-polarimetry, the solar atmosphere (Photosphere and Chromosphere) within a spectral range between 520 nm (optionally 280 nm) and 1,100 nm.

Multi-purpose grating spectrograph for the 4-meter European Solar Telescope

This communication presents a family of spectrographs designed for the European Solar Telescope. They can operate in four different configurations: a long slit standard spectrograph (LsSS), two devices based on subtractive double pass (TUNIS and MSDP) and one based on an integral field, multi-slit, multi-wavelength configuration. The combination of them composes the multi-purpose grating spectrograph of EST, focused on supporting the different science cases of the solar photosphere and chromosphere in the spectral range from 3900 Å to 23000 Å. The different alternatives are made compatible by using the same base spectrographs and different selectable optical elements corresponding to specific subsystems of each configuration.