HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450 nm to 2450 nm with resolving powers from 3500 to 18000 and spatial sampling from 60 mas to 4 mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. The project is preparing for Final Design Reviews. HARMONI is a work-horse instrument that provides efficient, spatially resolved spectroscopy of extended objects or crowded fields of view. The gigantic leap in sensitivity and spatial resolution that HARMONI at the ELT will enable promises to transform the landscape in observational astrophysics in the coming decade. The project has undergone some key changes to the leadership and management structure over the last two years. We present the salient elements of the project restructuring, and modifications to the technical specifications. The instrument design is very mature in the lead up to the final design review. In this paper, we provide an overview of the instrument's capabilities, details of recent technical changes during the red flag period, and an update of sensitivities.
Due to the complexity of scientific instruments, such as spectropolarimeters, managing instrument sequences can be challenging. To address this problem, a Finite-State Machine (FSM) approach has been used to manage solar observation sequences in the GREGOR Infrared Spectrograph (GRIS). FSMs provide a structured and visual representation of control logic, making them well-suited for managing intricate workflows. By using FSMs, both scientists and engineers can clearly define and modify instrument sequences, ensuring the precise coordination of various instrument components. In multiple optical channels spectropolarimeters, such as GRIS, FSMs can effectively synchronize the image acquisition across multiple channels, adjust exposure times, handle errors, and manage the selection of the scanning system. To streamline the implementation process, the CodeDesigner RAD tool was used to create diagrams that illustrate the execution order of the states belonging to a finite-state machine. CodeDesigner’s code generation feature automatically translates these diagrams into C++ code. This approach ensures the precise and reliable operation of the GRIS control software.
EMIR (Espectrografo Multiobjeto Infra-Rojo) is a wide field, near infrared, multiobject spectrograph, with image capabilities, which is currently located at one of the Nasmyth focus of the 10.4m GTC (Gran Telescopio Canarias). It allows observers to obtain many intermediate resolution spectra simultaneously, in the near IR bands: Z, J, H and K. A configurable cryogenic multislit mask unit provides target acquisition too. This paper describes the upgrade of EMIR (to EMIR+) which incorporates a new Teledyne H2RG infrared detector, using the SIDECAR integrated controller and a Markury Scientific MACIE interface card over IP communication. A detailed description of the Data Acquisition System (DAS), integrated into the GTC Control System (GCS) software, is given. It configures the URG or FS acquisition modes, starts the acquisition process, capture the data coming from the H2RG unit, stores the FITS data and propagate the images to produce astronomical files. We also developed a Python-based MACIE Controller Simulator to test and debug the DAS, which works as a real MACIE interface, responding to all petitions and generating test images to feed the DAS or other control programs.
The European Solar Telescope (EST) is a 4.2-metre telescope that will be equipped with a multi-conjugate adaptive optics (MCAO) system to provide a high spatial resolution over a circular field of view with 60” diameter. The EST-MCAO testbed is a downscaled demonstrator of solar MCAO with similar requirements to those defined for EST. It has been designed and developed to identify and better understand the capabilities of this system. Before MCAO implementation, different AO configurations must be first evaluated in the testbed. Single conjugate adaptive optics for point-like sources has been identified as the first step towards MCAO for the EST. This configuration is based on the use of a deformable mirror with 820 actuators and a Shack-Hartmann wavefront sensor with 33x33 subapertures. The main objective of this paper is to present the results obtained in the EST-MCAO testbed when testing different phase reconstruction algorithms and closed-loop schemes to deal with SCAO for point-like sources. Center of gravity technique was proposed for local slope computation when using point-like sources. Both zonal and modal approaches, including SVD and their regularized least-squares versions, were evaluated and tested for the reconstruction. A closed-loop strategy based on a proportional-integral controller was initially proposed. The benefits of pseudo open-loop control were also evaluated. The performance of the algorithms was tested considering different seeing conditions. Finally, a comparison based on RMS wavefront error and Strehl Ratio was conducted.
Once the design phase of the Multi-Conjugated Adaptive Optics (MCAO) testbed for the European Solar Telescope (EST) is completed, the system has been assembled and integrated at the Instituto de Astrofísica de Canarias (IAC). The aim of this highly configurable optical testbed is to study different solar adaptive optics solutions, including Single Conjugated Adaptive Optics (SCAO), Ground Layer Adaptive Optics (GLAO), and MCAO. The testbed will be used to evaluate the performance of different wavefront sensing and correction strategies. It consists of different subsystems that are being integrated with high precision by using optomechanical elements mostly developed at IAC. The testbed emulates a 4-m telescope with a Field of View (FoV) of 70 arcseconds. It currently operates as a SCAO configuration consisting of: an illumination system with point-like and extended source capability coupled with a configurable turbulence simulator based on Phase Screens (PS); a pupil-conjugated Deformable Mirror (DM) with 820 actuators; a high order Shack-Hartmann Wavefront Sensor (SH-WFS) with 33 subapertures across the pupil, which measures on-axis aberrations with a FoV of 10 arcseconds; and the science detector. The next steps include the integration of the elements that will provide GLAO and MCAO capabilities, such as two SH-WFSs with a FoV of 70 arcseconds, and two DMs conjugated to different atmospheric layers. This contribution describes the optomechanical components designed and the alignment procedure carried out to set up each subsystem and configuration to be studied.
The European Solar Telescope (EST) is a 4.2-m telescope which has been redesigned with a fully integrated Multi-Conjugate Adaptive Optics (MCAO) into the optical path right after the EST primary mirror. The current baseline configuration considers four altitude Deformable Mirrors (DM) conjugated to 5, 9, 12 and 20 km above the telescope entrance pupil and an Adaptive Secondary Mirror (ASM) conjugated to the entrance pupil. The wavefront sensing will be performed by a set of correlation-based Shack Hartmann wavefront sensors (WFS) combining an on-axis High-Order WFS (HOWFS) to be used either in Single Conjugate AO (SCAO) to drive the ASM as well as operating simultaneously with a Multi-Directional WFS (MDWFS) to drive the MCAO. Beyond the current baseline configuration, different alternatives are currently being investigated both in the wavefront sensing strategy by evolving from a HOWFS+MDWFS into possibly a single High Order Multi Directional WFS (HOMDWFS) and/or wavefront sensors operating at different observing bands.
The GREGOR Infrared Spectrograph (GRIS) can perform spectropolarimetric observations in 1.0-1.8 μm and pure spectroscopic in the band 2.0-2.3 μm. The spectrograph has a Czerny-Turner design and has allowed the operation in the traditional long-slit mode since 2014. And also, in IFU mode since was upgraded in 2018. A third upgrade took place in 2021, where optomechanical, control and software improvements have been conducted to introduce a new spectral channel that receives light below 900 nm. This new spectral channel allows simultaneous observations with the previous infrared camera. Additional improvements include replacing the old diffraction grating with a new one and acquiring a sensor for the new spectral channel. The new grating allows having different order separation and maximising the combination of spectral bands of interest between both channels. Also, a dichroic was placed after the focal plane of the spectrograph, and a reimaging system was introduced in the new spectral channel to match the spatial scale (arcsec/px) in the old and new detectors. The feasibility of operating both cameras simultaneously, and synchronised with the polarisation modulation package, has been already tested. This work describes the optical design for all the spectral channels. We also examine its optical performance, as well as discussing future upgrades in terms of additional spectral channels that are already in progress.
This contribution describes the software and electronic improvements implemented in the GREGOR Infrared Spectrograph (GRIS) installed on the Gregor telescope. It is located at the Teide Observatory, in Tenerife, Islas Canarias, Spain. As a demonstrator for an instrument for the European Solar Telescope (EST), this project aims to perform simultaneous spectropolarimetric observations in several spectral lines using several synchronized detectors that may operate at different synchronized frame rates. Throughout the article, the problems encountered in achieving the synchronization of two or more sensors and the solutions proposed to solve them are explained.
The European Solar Telescope (EST) aims to become the most ambitious ground-based solar telescope in Europe. Its roots lie in the knowledge and expertise gained from building and running previous infrastructures like, among others, the Vacuum Tower Telescope, Swedish Solar Telescope, or the GREGOR telescope. They are installed in the Canary Islands observatories, the selected EST site. Furthermore, the telescope has a novel optical design, including an adaptive secondary mirror (ASM) that allows reducing the number of optical surfaces to 6 mirrors (plus two lenses) before the instruments’ focal plane. The latter, combined with a configuration of mirrors that are located orthogonally oriented to compensate for the instrumental polarisation induced by each surface, makes EST a reference telescope in terms of throughput and polarimetric accuracy. In its main core design, EST also includes a Multi-Conjugated Adaptive Optics (MCAO) system where the ASM compensates for the ground layer turbulence. The rest of the mirrors on the optical train correct for the atmospheric turbulence at different layers of the atmosphere. The MCAO guarantees that the large theoretical spatial resolution of the 4-metre EST primary mirror is achieved over a circular FOV of 60 arcsec. Those main elements, combined with a set of instruments with capabilities for spectropolarimetry, make EST the next frontier in solar ground-based astronomy. In this contribution, we will cover the main properties and status of all the mentioned sub-systems and the following steps that will lead to the construction phase.
For more than ten years, the GREGOR Infrared Spectrograph (GRIS) has been the main spectropolarimeter on the GREGOR telescope since its inauguration in 2012. The instrument mainly performs polarimetric observations of the wavelength regions at 1083 and 1565 nm, with high scientific potential. There, observers can find spectral lines that provide information on the atmospheric parameters over a vast range of atmospheric layers and with high sensitivity to the magnetic field. Due to the high demand for GRIS and the versatility of the GREGOR environment, we decided to upgrade the system once more, allowing it to become one of the instruments with the highest potential in any ground-based solar observatory. This time, the upgrades add two spectral channels for performing multi-wavelength observations, either in long-slit or IFU mode.
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