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.<p> </p> 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.<p> </p> 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.
The quality of SiFAP (Silicon Fast Astronomical Photometer) at the TNG has already shown its ability to easily detect optical pulses from transitional millisecond pulsars and from other slower neutron stars. Up to now the photometer based on Silicon Photo Multipliers manufactured by Hamamatsu Photonics (MPPC, Multi Pixel Photon Counter) was mounted (on and manually aligned with) a MOS mask at the F/11 focal plane of the telescope. In order to have a more versatile instrument with the possibility to remotely center and point several targets during the night we have decided to build a new mechanical support for the MPPCs and mount it on the Namsyth Interface (NI), where originally OIG and later GIANO were hosted. The MPPC module devoted to observe the target will be placed at the center of the FoV (on-axis), while the reference signal will be collected from a peripheral star in the FoV (Field of view) by means of the MPPC module that will be set at this position by a combination of a linear stage movement and a derotator angle. At the same time we have introduced the option for a polarimetric mode, with a 3rd MPPC module and a polarizing cube beam-splitter that separates the states between this and the on axis MPPC. SiFAP has been developed with 3 independent custom electronic chains for data acquisition, exploiting the 3 different outputs (analog, digital, USB pre-processed) provided by the MPPCs modules. The electronic chain fed by the analog output is able to tag a single photon ToA (Time of Arrival) with a time resolution of 25 ns, while the remaining electronic chains can integrate the signal into time bins from 100 ms down to 20 μs. The absolute time is provided by a GPS unit with a time resolution of 25 ns at 50% of the rising edge of the 1PPS (1 Pulse Per Second) signal which is linked to the UTC (Universal Time Coordinated). Apart from the versatility with the remotely controlled on sky configuration of the MPPCs, the mounting of SiFAP2 at the NI allows for a permanent hosting of the instrument, readily available for observations. The new polarimetric mode will then offer other scientific opportunities that have not been explored so far in high-temporal resolution astronomy.
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.
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.
This paper, “Astrometry at micro-arcsec resolution: optical design aspects and technology issues," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.
Using a turn-key Ti:sapphire femtosecond laser frequency comb, an off-the-shelf supercontinuum device and Fabry-Perot mode filters, we report the generation of a 16-GHz frequency comb spanning a 90-nm band about a center wavelength of 566 nm. The light from this astro-comb is used to calibrate the HARPS-N astrophysical spectrograph for precision radial velocity measurements. The comb-calibrated spectrograph achieves a stability of ∼1 cm/s within half an hour of averaging time. We also use the astro-comb as a reference for measurements of solar spectra obtained with a compact telescope and as a tool to study intrapixel sensitivity variations on the spectrograph detector.
The Multi-AO Imaging Camera for Deep Observations (MICADO), a first light instrument for the 39 m European Extremely Large Telescope (E-ELT), is being designed and optimized to work with the Multi-Conjugate Adaptive Optics (MCAO) module MAORY (0.8-2.5 μm). The current concept of the MICADO instrument consists of a structural cryostat (2.1 m diameter and 2 m height) with the wavefront sensor (WFS) on top. The cryostat is mounted via its central flange with a direct interface to a large 2.5-m-diameter high-precision bearing, which rotates the entire camera (plus wavefront sensor) assembly to allow for image derotation without individually moving optical elements. The whole assembly is suspended at 3.6 m above the E-ELT Nasmyth platform by a Hexapod-type support structure. We describe the design of the MICADO derotator, a key mechanism that must precisely rotate the cryostat/SCAO-WFS assembly around its optical axis with an angular positioning accuracy better than 10 arcsec, in order to compensate the field rotation due to the alt-azimuth mount of the E-ELT. Special attention is being given to simulate the performance of the derotator during the design phase, in which both static and dynamics behaviors are being considered in parallel. The statics flexure analysis is done using a detailed Finite Element Model (FEM), while the dynamics simulation is being developed with the mathematical model of the derotator implemented in Matlab/Simulink. Finally, both aspects must be combined through a realistic end-to-end model. The experiment designed to prove the current concept of the MICADO derotator is also presented in this work.
GIARPS (GIAno and haRPS) is a project devoted to have on the same focal station of the Telescopio Nazionale Galileo (TNG) both the high resolution spectrographs HARPS-N (VIS) and GIANO (NIR) working simultaneously. This could be considered the first and unique worldwide instrument providing cross-dispersed echelle spectroscopy at a high resolution (R=115,000 in the visual and R=50,000 in the IR) 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 the large wavelength range. A number of outstanding science cases encompassing mainly extra-solar planet science starting from rocky planet search and hot Jupiters, atmosphere characterization can be considered. Furthermore both instrument can measure high precision radial velocity by means the simultaneous thorium technique (HARPS - N) and absorbing cell technique (GIANO) in a single exposure. Other science cases are also possible. Young stars and proto- planetary disks, cool stars and stellar populations, moving minor bodies in the solar system, bursting young stellar objects, cataclysmic variables and X-ray binary transients in our Galaxy, supernovae up to gamma-ray bursts in the very distant and young Universe, can take advantage of the unicity of this facility both in terms of contemporaneous wide wavelength range and high resolution spectroscopy.
We recently demonstrated sub-m/s sensitivity in measuring the radial velocity (RV) between the Earth and Sun using a simple solar telescope feeding the HARPS-N spectrograph at the Italian National Telescope, which is calibrated with a green astro-comb. We are using the solar telescope to characterize the effects of stellar (solar) RV jitter due to activity on the solar surface with the goal of detecting the solar RV signal from Venus, thereby demonstrating the sensitivity of these instruments to detect true Earth-twin exoplanets.
Usually observational astronomy is based on direction and intensity of radiation considered as a function of wavelength
and time. Despite the polarisation degree of radiation provides information about asymmetry, anisotropy and magnetic
fields within the radiative source or in the medium along the line of sight, it is commonly ignored. Because of the
importance of high resolution spectropolarimetry to study a large series of phenomena related to the interaction of
radiation with matter, as in stellar atmospheres or more generally stellar envelopes, we designed and built a dual beam
polarimeter for HARPS-N that is in operation at the Telescopio Nazionale Galileo. Since the polarisation degree is
measured from the combination of a series of measurements and accuracy is limited by the instrumental stability, just the
great stability (0.6 m/s) and spectral resolution (R=115000) of the HARPS-N spectrograph should result in an accuracy
in the measurements of Stokes parameters as small as 0.01%. Here we report on the design, realization, assembling,
aligning and testing of the polarimetric unit whose first light is planned in August 2014.
We report on the results of the conceptual design study of a broad band imager for the European Solar Telescope (EST),
a joint project of several European research institutes to design and realize a 4-m class solar telescope. The EST broad
band imager is an imaging instrument whose function is to obtain diffraction limited images over the full field of view of
EST at multiple wavelengths and high frame rate. Its scientific objective is the study of fundamental astrophysical
processes at their intrinsic scales in the Sun’s atmosphere. The optical layout foresee two observational modes: a
maximum field of view mode and a high resolution mode. The imager will have a 2'x2' corrected field of view in the first
mode and an angular resolution better than 0.04" at 500nm in the latter mode. The imager will cover a wavelength range
spanning from 390nm to 900nm through a number of filters with bandpasses between 0.05nm and 0.5nm. The selected
optical layout is an all refractive design. To optimize optical performances and throughput there will be two arms
working simultaneously: a blue arm (covering the 380nm – 500nm range) and a red arm (600nm – 900nm). The blue arm
will have two channels while the red arm only one. Each channel will be divided in three subchannels: one will host
narrow band filters for chromospheric observations, another one, in focus wide band filters used as reference for speckle
reconstruction and photospheric observations, and the last one, out of focus wide band filters for phase diversity
reconstruction of photospheric observations.
Innovative optical interferometry test setups and control software techniques have been proposed for the E-ELT M4
adaptive optics mirror. The system is composed of three sub-systems: a CGH-based optical test tower, delivering a 1.5-
m collimated beam, for fast simultaneous acquisition of large areas; a stitching interferometer, to calibrate at higher
spatial frequencies, on smaller areas; and an optical piston sensor to remove differential piston and tilt between adjacent mirror segments.
The European Solar Telescope (EST) is a joint project of several European research institutes to design and realize a 4-m
class solar telescope. The EST broad band imager is an imaging instrument whose function is to obtain diffraction
limited images over the full field of view of EST at multiple wavelengths and high frame rate. Its scientific objective is
the study of fundamental astrophysical processes at their intrinsic scales in the Sun's atmosphere. The current layout
foresee two observation modes: a maximum field of view mode and a high resolution mode. The imager will have a 2'x2'
corrected field of view in the first mode and an angular resolution better than 0.04" at 500nm in the latter mode. The
imager will cover a wavelength range spanning from 390nm to 900nm through a number of filters with bandpasses
between 0.05nm and 0.5nm. To optimize optical performances and throughput there will be two arms working
simultaneously: a blue arm (covering the 380nm - 500nm range) and a red arm (600nm - 900nm). The blue arm will
have two channels while the red arm only one. Each channel will be divided in three subchannels: one will host narrow
band filters for chromospheric observations, another one, in focus wide band filters used as reference for speckle
reconstruction and photospheric observations, and the last one, out of focus wide band filters for phase diversity
reconstruction of photospheric observations.
The Adaptive Optics Module of the Telescopio Nazionale Galileo (AdOpt@TNG) has enjoyed a huge refurbishment. A new WaveFront Sensing CCD (EEV39 80x80pixels by SciMeasure) has been mounted, allowing for up to 1KHz frame rate. Thanks to the versatility of the pyramid wavefront sensor, the fast changing of the 4x4 and 8x8 pupil sampling has been easily and successfully implemented. A dual pentium processor PC with Real-Time Linux has substituted the old VME as Real Time Computer. The implementation of the new Deformable Mirror by Xinetics will be also discussed. A new Graphical User Interface has been built to allow for user-friendly utilization of the module by astronomers. On-sky observations will be presented in terms of FWHM and Strehl Ratio for different values of guiding star magnitudes and seeing conditions. The encouraging on-sky results and overall system stability pushed to offer AdOpt@TNG to the international astronomical community.
The Adaptive Optics System of the Galileo Telescope (AdOpt@TNG) is the only adaptive optics system mounted on a telescope which uses a pyramid wavefront snesor and it has already shown on sky its potentiality. Recently AdOpt@TNG has undergone deep changes at the level of its higher orders control system. The CCD and the Real Time Computer (RTC) have been substituted as a whole. Instead of the VME based RTC, due to its frequent breakdowns, a dual pentium processor PC with Real-Time-Linux has been chosen. The WFS CCD, that feeds the images to the RTC, was changed to an off-the-shelf camera system from SciMeasure with an EEV39 80x80 pixels as detector. While the APD based Tip/Tilt loop has shown the quality on the sky at the TNG site and the ability of TNG to take advantage of this quality, up to the diffraction limit, the High-Order system has been fully re-developed and the performance of the closed loop is under evaluation to offer the system with the best performance to the astronomical community.
Since 1999 the National Telescope Galileo (TNG) is offering observative nights to the astronomical community. With the aim of increase the efficiency of the telescope and minimize downtime many changes have been done from the original project. Recently it has been taken the decision to completely renew the electronic hardware and software of the active optics system, essencially based on VMEs and on the obsolete transputers processors. From the optical point of view some important modifications have also been implemented in order to allow the off-axis Shack-Hartmann analisys. Also the CCD cameras and their controllers have been redeveloped and the whole control software has been ported to a new architecture to by-pass the VMEs system and directly interact with the actuators and the CCD controllers.
Layer Oriented represented in the last few years a new and promising aproach to solve the problems related to the limited field of view achieved by classical Adaptive Optics systems. It is basically a different approach to multi conjugate adaptive optics, in which pupil plane wavefront sensors (like the pyramid one) are conjugated to the same altitudes as the deformable mirrors. Each wavefront sensor is independently driving its conjugated deformable mirror thus simplifying strongly the complexity of the wavefront computers used to reconstruct the deformations and drive the mirror themselves, fact that can become very important in the case of extremely large telescopes where the complexity is a serious issue. The fact of using pupil plane wavefront sensors allow for optical co-addition of the light at the level of the detector thus increasing the SNR of the system and permitting the usage of faint stars, improving the efficiency of the wavefront sensor. Furthermore if coupled to the Pyramid wavefront sensor (because of its high sensitivity), this technique is actually peforming a very efficient usage of the light leading to the expectation that, even by using only natural guide stars, a good sky coverage can be achieved, above all in the case of giant telescopes. These are the main reasons for which in the last two years several projects decided to make MCAO systems based on the Layer Oriented technique. This is the case of MAD (an MCAO demonstrator that ESO is building with one wavefront sensing channel based on the Layer Oriented concept) and NIRVANA (an instrument for LBT). Few months ago we built and successfully tested a first prototype of a layer oriented wavefront sensor and experiments and demonstrations on the sky are foreseen even before the effective first light of the above mentioned instruments. The current situation of all these projects is presented, including the extensive laboratory testing and the on-going experiments on the sky.
The Adaptive Optics for the Telescopio Nazionale Galileo module (namely AdOpt@TNG) implements the pyramid wavefront sensor as a unique feature. This allows to get valuable information on its performance on the sky. An updated overview of the results obtained
so far is shown, including a discussion on the sources of errors in the closed loop operation, distinguishing them between the ones specific of the pyramid wavefront sensor and the one more related to the system as a whole. This system allows also for a number of experiments and check of the sensitivity of such a wavefront sensor, especially in comparison with other types of sensing units. The ways to accomplish such an experiment in a convincing way are shown along with the first results obtained so far. Finally, we describe how and up to which extent a number of practical problems encountered in the near past can be solved implementing the recent new ideas on the pyramid theme, many of which popped up from our "lessons learned".
In order to get first-hand results in the laboratory and possibly on the sky with the Layer-Oriented approach we designed, built, and tested a bread-board for this type of wavefront sensor. This device consists of a single wavefront sensor able to look simultaneously at four references. The positioning of three of the four reference stars with respect to the central one is made by the means of manually adjustable positioning units. A few additional degrees of freedom have been intentionally placed in the system in a way to test the sensitivity of the unit to misplacement and/or misalignment of some optical components. The laboratory set-up includes a crude system to mimic a telecentric F/32 focal plane illuminated by a number of fiber sources that can be placed in several different configurations. Wavefront deformation can be accomplished by placing some fixed deformating plates optically conjugated to several altitudes on the atmosphere. The system is designed in a way to be easily fitted to the existing AdOpt@TNG system, allowing for multiple references, one DM, closed loop operations. Any preliminar result from this activity will be reported. Laboratory experiments includes checking of the theoretical predictions, especially the effectiveness in sensing up to a certain spatial frequency the layers not specifically conjugated to the detector. The results of a demonstrative experiment, showing how the wavefront sensor is able to disentangle layers contribution, are also reported.
For reasonable Field of View (of the order of several arcmin), the pupil overlap in the high altitude layers is marginal or non existing for 8m class telescopes and dominant for 100m class apertures. Starting from this matter of fact, we formulated a multiple resolution, multiple Field of View version of the layer oriented adaptive optics approach which looks at the same layer with field apertures and spatial resolution that are mutually compensating each other: a larger field, allowing for the collection of more photons from natural stars, is used to sample the layer with a finer spatial detail, and viceversa. In this way the small field of view, with coarse spatial sampling, gives information on the behavior of the atmosphere for a large thickness around the focused layer, at the expense of the detailed information in a thin slab centered on the layer itself. Such lacking information is obtained from the wider field channel. This requires the coaddition of the two pieces of information at the level of the Fourier pair of the reimaged layer, which can be accomplished, in a practical way, directly in the spatial domain rather than in the Fourier one. The consequences on the sky coverage estimations and on the hardware implementations are discussed. Finally some comments are given about other degrees of freedom that can be used to improve the performance of layer oriented adaptive optics.
The concept of Pyramid Wavefront sensor has been introduced as a more compact and flexible alternative to Shack--Hartmann wavefront sensing. In the past five years, however, such a novel concept promised a much larger sensitivity and an inherent easiness to be implemented in a multiple reference wavefront sensor. AdOptTNG, a natural guide star based adaptive optics module implemented at the 3.5m TNG telescope is equipped with such a sensor. We report here on the updated status, including on-sky experimental verification of various of the several features of such a sensor. We discuss the results obtained, their scalability and the lessons learned in building, aligning and operating it. Some comparison with theoretical and laboratory-based result, is also tentatively reported.
Within a Technology Research Program funded by the European Space Agency, a team led by Alenia Aerospazio has investigated and started the development of some technologies which are considered fundamental for the achievement of the scientific objectives of the future astrometric mission GAIA. The activities have been focused on the design of a two-aperture optical interferometer and of a system for the active stabilization of its configuration within few picometers. A laboratory prototype of the active stabilization system has been implemented and tested. The results achieved in the laboratory tests proved that the very challenging requirements imposed by the GAIA astrometric goal of 10 micro-arcsec accuracy can be fulfilled.
Some solutions for the case of two-mirror three-reflection telescope assuming to use really two mirrors (first reflection on a surface strictly equal to the one related to the third reflection) are briefly described. This work is a by-product of the efforts of a larger team for the conceptual design of wide field UV space mission.
The active real-time cophasing of an interferometer, that is, the fulfillment of the condition (Delta) (OPD) >> (lambda) (OPD is the Optical Path Difference between every pair of light beams, each coming from every telescope of the array is a crucial requirement for high resolution and long exposure image formation. So the optical concept is a possible design of a Cophasing System (CS hereafter) for a space interferometer, e.g. the Multimirror Ultraviolet Solar Telescope (MUST), will be presented. A collimator and a pair of achromatic wedges are two of its components; the former has the target to collimate light beams which enter in the CS preserving the instrumental errors due to aberrations much less than (lambda) in the Optical Path Length (OPL) of the light beams; the latter allows to choose any region of the Field of View (FoV) of the beams by their simple rotation (two degree of freedom correspond to a FoV point) in order to have high contrast features used in telescopes pre- alignment subsystem included in the CS. Ray tracing results on these optical components will be show. Their tolerance analysis will also be discussed. A mechanical approach for each wedge rotation will be shown together with a preliminary CAD arrangement of the subsystem in a cylindrical package of diameter approximately equals 300 mm and approximately equals 100 mm height.