LOCNES (LO-Cost NIR Extended Solar telescope) is a solar telescope installed at the TNG (Telescopio Nazionale Galileo) in the Canary Islands. It feeds the Sun’s light into the NIR spectrograph GIANO-B through a 40-m patch of optical fibers. LOCNES has been designed to obtain high signal-to-noise ratio spectra of the Sun as a star with an accurate wavelength calibration through molecular-band cells. This is an entirely new area of investigation that will provide timely results to improve the search of telluric planets with NIR spectrographs such as iSHELL, CARMENES, NIRPS, and GIANO-B. We will extract several disc-integrated activity indicators and average magnetic field measurements for the Sun in the NIR. These parameters will then be correlated with both the RV of the Sun as a star and the resolved images of the solar disc in visible and NIR. Such an approach will allow for a better understanding of the origin of activity-induced RV variations in the two spectral domains and will help in improving the techniques for their corrections. LOCNES has been installed on the outer part of the TNG dome and it started its operation in the 2023 Springtime when we performed the commissioning of the solar telescope. The main results of the commissioning will be highlighted in this paper.
LOCNES (Low Cost NIR Extended Solar Telescope) is a newly installed solar telescope at the Telescopio Nazionale Galileo. This small telescope has been specifically developed to examine the infrared spectrum of the Sun with the GIANO-B high resolution infrared spectrograph. LOCNES observes the Sun by integrating the entire solar disk, so its observations lack any spatial resolution and are comparable to what can typically be obtained for any other star. This observational method is commonly referred to as” Sun-as-a-star” observations. In this paper we provide an overview of the LOCNES Instrument Control Software (ICSS), which is in charge of controlling the dome, the telescope, and enable the acquisition of spectra with GIANO-B. We illustrate the control network, the instrument functions and elements to be controlled, the overall design of LOCNES Instrument Control Software and its main components.
In this paper, we introduce the scheduler for Radial Velocity (RV) measurements at the TNG telescope which is currently under development. The scheduler is a web-based application designed to optimize RV observations for GAPS community science projects. Additionally, it will be made available to all other follow-up RV programs that wish to benefit from it. We will detail the process of inputting, prioritizing, and selecting targets for observation with HARPS-N and GIANO-B at the TNG, while ensuring appropriate allocation, respecting the timing and constraint, among all the programs that use this scheduler to optimize their measurements. This fully automated software will be able to flank the observer with a night-by-night ordered list of optimal targets, as well as optimal backups in case observing conditions change, enabling users to adapt to rapid changes due to weather conditions that require a swift response, without compromising the optimization process, ensuring high-quality observations. We foresee to provide the scheduler with a web-based panel that interrogates the underlying application programming interfaces to load/reload/edit the calculated OBs list and export them for execution by the telescope operator.
We present the results of the ground-based observing campaign to build the grid of Spectro-Photometric Standard Stars (SPSS) for the absolute flux calibration of data gathered by Gaia, the European Space Agency (ESA) astrometric mission. The spectro-photometric standard stars catalog is characterized by an internal ≅1% accuracy (and sub-percent precision) and it is tied to the CALSPEC Vega and Sirius systems within ≅1%. The final list of SPSS and their flux tables are presented, together with all the quality parameters and associated stellar properties derived from Gaia and the literature. Improvements with respect to the previous SPSS release (Pancino et al. 2021) are discussed, concerning especially the flux accuracy in the red part of the spectrum, above 800 nm. The grid will be used to calibrate Gaia photometry and spectra fluxes in the DR4 and DR5 releases.
KEYWORDS: Off axis mirrors, Dielectric mirrors, Spectrographs, Spherical lenses, Light sources and illumination, Parabolic mirrors, Telescopes, Signal to noise ratio, Optical components, Windows
The first generation of ELT instruments includes an optical-infrared High Resolution Spectrograph: ANDES (ArmazoNes high Dispersion Echelle Spectrograph). This paper describes the design of the Integral Field Unit (IFU): the focal plane of the ELT is reimaged at different scales (down to the diffraction limit) and fed into a bundle of fibers that covers a small hexagonal field of view that terminate in a linear structure aligned along the spectrometer slit.
In 2014 TNG also offered GIANO-B to the scientific community, providing a near-infrared (NIR) cross-dispersed echelle spectrograph covering 0.97 − 2.45 µm at a resolution of 50000. The possibility of simultaneously using GIANO-B together with the HARPS-N spectrograph (GIARPS observing mode) has been particularly appealing especially for the search of exoplanets by means high precision radial velocities. Moreover, GIANO-B triggered the possibility to observe in the NIR the Sun as a star by means of LOCNES, a solar telescope that feeds the spectrograph by a bundle of NIR fibers, for study the activity of the Sun as a star in the NIR wavelength range and its impact on the radial velocity measurements. Both science cases, include high-precision radial-velocity studies down to 3 m/s which demand for specialized, highly accurate wavelength calibration techniques. In this paper we present a developed absorption gas-cell to enable high-precision wavelength calibration for GIANO-B as a modified model of the CRIRES+ Absorbing Cell. We also discuss the manufacturing difficulties and the new design of the vessel. Furthermore, the AIT and the commissioning of the cells is also reported.
We describe the preliminary results of a ground-based observing campaign aimed at building a grid of approximately 200 spectro-photometric standard stars (SPSS), with an internal ≅1% accuracy (and sub-percent precision), tied to CALSPEC Vega and Sirius systems within ≅1%, for the absolute flux calibration of data gathered by Gaia, the European Space Agency (ESA) astrometric mission. The criteria for the selection and a list of candidates are presented, together with a description of the survey's strategy and the adopted data analysis methods. All candidates were also monitored for constancy (within ±5 mmag, approximately). The present version of the grid contains about half of the final sample, it has already reached the target accuracy but the precision will substantially improve with future releases. It will be used to calibrate the Gaia (E)DR3 release of spectra and photometry.
LOCNES (LOw-Cost NIR Extended Solar telescope) is a solar telescope installed at the TNG (Telescopio Nazionale Galileo). It feeds the light of the Sun into the NIR spectrograph GIANO-B through a 40-m patch of optical fibers. LOCNES has been designed to obtain high signal-to-noise ratio spectra of the Sun as a star with an accurate wavelength calibration through molecular-band cells. This is an entirely new area of investigation that will provide timely results to improve the search of telluric planets with NIR spectrographs such as iSHELL, CARMENES, and GIANO-B. We will extract several disc-integrated activity indicators and average magnetic field measurements for the Sun in the NIR. Eventually, they will be correlated with both the RV of the Sun-as-a -star and the resolved images of the solar disc in visible and NIR. Such an approach will allow for a better understanding of the origin of activity-induced RV variations in the two spectral domains and will help in improving the techniques for their corrections. In this paper, we outline the science drivers for the LOCNES project and its first commissioning results.
GIANO-B is the high resolution near-infrared (NIR) spectrograph of the Telescopio Nazionale Galileo (TNG), which started its regular operations in October 2017. Here we present GIANO-B Online Data Reduction Software (DRS) operating at the Telescope.
GIANO-B Online DRS is a complete end-to-end solution for the spectrograph real-time data handling. The Online DRS provides management, processing and archival of GIANO-B scientific and calibration data. Once the instrument control software acquires the exposure ramp segments from the detector, the DRS ensures the complete data flow until the final data products are ingested into the science archive. A part of the Online DRS is GOFIO software, which performs the reduction process from ramp-processed 2D spectra to extracted and calibrated 1D spectra.
A User Interface (UI) developed as a part of the Online DRS provides basic information on the final reduced data, thus allowing the observer to take decisions in real-time during the night and adjust the observational strategy as needed.
GIANO is the IR high resolution spectrograph of the TNG. It covers the 950-2450 nm wavelengths range in a single shot at a resolving power of R=50,000. This document describes the first fundamental steps of the data reduction, namely eliminating the curvature of the traces and the tilt of the slit images. These effects can be accurately modeled and corrected using a physical model of the instrument. We find that the curvature and tilt parameters did not vary during the whole lifetime of the instrument. In particular, they were not affected by thermal cycles or by the works performed to mount the spectrometer on its new interface. A similar ab-initio modeling is also applied to the wavelength calibration that can be accurately (0.03 pixel r.m.s.) defined using a minimum number of parameters to fit. This approach is particularly useful when using a calibration source with an irregular wavelengths coverage; e.g. for the U-Ne lamp that has only few lines in the 2000 nm - 2300 nm wavelengths range.
GIARPS (GIAno and haRPS) is a project devoted to have on the same focal station of the Telescopio Nazionale Galileo (TNG) both high resolution spectrographs, HARPS–N (VIS) and GIANO–B (NIR), working simultaneously. This could be considered the first and unique worldwide instrument providing cross-dispersed echelle spectroscopy at a resolution of 50,000 in the NIR range and 115,000 in the VIS and over in a wide spectral range (0.383−2.45 μm) in a single exposure. The science case is very broad, given the versatility of such an instrument and its large wavelength range. A number of outstanding science cases encompassing mainly extra-solar planet science starting from rocky planets search and hot Jupiters to atmosphere characterization can be considered. Furthermore both instruments can measure high precision radial velocities by means the simultaneous thorium technique (HARPS–N) and absorbing cell technique (GIANO–B) in a single exposure. Other science cases are also possible. GIARPS, as a brand new observing mode of the TNG started after the moving of GIANO–A (fiber fed spectrograph) from Nasmyth–A to Nasmyth–B where it was re–born as GIANO–B (no more fiber feed spectrograph). The official Commissioning finished on March 2017 and then it was offered to the community. Despite the work is not finished yet. In this paper we describe the preliminary scientific results obtained with GIANO–B and GIARPS observing mode with data taken during commissioning and first open time observations.
KEYWORDS: Calibration, Lamps, Sensors, Spectrographs, Signal to noise ratio, Infrared radiation, Spectroscopy, Signal detection, Data processing, Near infrared spectroscopy
The NIR echelle spectrograph GIANO-B at the Telescopio Nazionale Galileo is equipped with a fully automated online DRS: part of this pipeline is the GOFIO reduction software, that processes all the observed data, from the calibrations to the nodding or stare images. GOFIO reduction process includes bad pixel and cosmic removal, flat-field and blaze correction, optimal extraction, wavelength calibration, nodding or stare group processing. An offline version of GOFIO will allow the users to adapt the reduction to their needs, and to compute the radial velocity using telluric lines as a reference system. GIANO-B may be used simultaneously with HARPS-N in the GIARPS observing mode to obtain high-resolution spectra in a wide wavelength range (383-2450 nm) with a single acquisition. In this framework, GOFIO, as part of the online DRS, provides fast and reliable data reduction during the night, in order to compare the infrared and visible observations on the fly.
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