Search

The Large Fiber Array Spectroscopic Telescope (LFAST) concept involves the utilization of 2640 individual, 0.76 m "unit telescopes" to collect light from a target object. Through optical fibers, the lights from all telescope foci are directed to a high-resolution spectrograph, with fibers subtending a 1.47 arcsec diameter on the sky. The total light-collecting area of all telescopes combined is 1200 m2. Given the telescope's application for spectroscopy of seeing-limited images, the need for coherence is eliminated. The primary goal of the LFAST prototype is to demonstrate a telescope design that can be rapidly and cost-effectively replicated to achieve a 1200 m2 collecting area and match the capabilities of extremely large telescopes (ELTs) presently under construction. Engineering, manufacturing, and design challenges unique to LFAST differ significantly from those encountered in traditional ELTs. Considering that the unit telescope is to be replicated thousands of times, reducing the manufacturing cost per telescope is essential. The aim of the described design is to achieve this goal, with strong considerations for manufacturability, alignment, few moving parts, and high yield. Experience from the first prototype unit telescope built in 2022 will be leveraged to build the first 20-unit tracking module in 2024, with a collecting area of a 3.4-m-diameter mirror. The design is minimalistic and features commercial tolerances, thereby ensuring cost-effectiveness in manufacturing, assembly, and alignment processes. Moreover, the telescope is designed to operate at angles as low as 70° from the zenith by laterally translating a single lens to correct for atmospheric dispersion. We present a combined average of over 80% encircled energy across 2640 Monte Carlo trials. Simulations were conducted using commercially specified tolerances and capabilities to model the overall performance of the array. Highlights: LFAST is an "array telescope" designed to combine light from multiple telescopes. We design a telescope that is highly performing, even at elevations as low as 70° from the zenith. Monte Carlo trials show that 80% average encircled energy can be achieved with standard tolerances for 2640 telescopes. [ABSTRACT FROM AUTHOR]

We present an analysis of high-dispersion spectroscopic observations of the symbiotic system R Aquarii (R Aqr) obtained with the Manchester Echelle Spectrograph at the 2.1-m telescope of the San Pedro Mártir Observatory (Mexico) in conjunction with available narrow-band images. The data are interpreted by means of the shape software to disclose the morpho-kinematics of the nebulosities associated with R Aqr. The model that best reproduces narrow-band images and position–velocity diagrams consists of three structures: an outer (large) hourglass structure surrounding an inner bipolar with a spiral-like filament entwined around the latter. The expansion velocity pattern of each structure is defined by different homologous expansion laws, which correspond to kinematic ages of |$\tau _1$|  = 450 |$\pm$|  25 yr (outer hourglass), |$\tau _2$|  = 270 |$\pm$|  20 yr (inner bipolar), and |$\tau _3$|  = 285 |$\pm$|  20 yr (spiral-like filament). We suggest that the spiral-like filament is tracing the regions of the interaction of a precessing jet with the circumstellar material, which simultaneously carves the inner bipolar structure. If a similar process created the large hourglass structure, it means that the action of the jet ceased for about 170 yr. We discuss the implications for other unresolved symbiotic systems detected in X-rays. [ABSTRACT FROM AUTHOR]

Measuring the absolute brightness of the zodiacal light (ZL), which is the sunlight scattered by interplanetary dust particles, is important not only for understanding the physical properties of the dust but also for constraining the extragalactic background light (EBL) by subtracting the ZL foreground. We describe the results of high-resolution spectroscopic observations of the night sky in the wavelength range of 300–900 nm with the double spectrograph on the Hale telescope to determine the absolute brightness of the ZL continuum spectra from the Fraunhofer absorption line intensities. The observed fields are part of the fields observed by the Spitzer Space Telescope for the EBL study. Assuming that the spectral shape of the zodiacal light is identical to the solar spectrum in a narrow region around the Fraunhofer lines, we decomposed the observed sky brightness into multiple emission components by amplitude parameter fitting with spectral templates of the airglow, ZL, diffuse Galactic light, integrated starlight, and other isotropic components including EBL. As a result, the ZL component with the Ca  ii  λλ 393.3, 396.8 nm Fraunhofer lines around 400 nm is clearly separated from the others in all fields with uncertainties around 20%, mainly due to the template errors and the time variability of the airglow. The observed ZL brightness in most of the observed fields is consistent with the modeled ZL brightness calculated by combining the most conventional ZL model at 1250 nm based on the Diffuse Infrared Background Experiment and the observational ZL template spectrum based on the Hubble Space Telescope. However, the ecliptic plane observation is considerably fainter than the ZL model, and this discrepancy is discussed in terms of the optical properties of the interplanetary dust accreted in the ecliptic plane. [ABSTRACT FROM AUTHOR]

The proposed lunar telescope for optical and infrared astronomy aims at very large aperture, 600 m2, at a fundable cost. It comprises an array of 18 separate telescopes, each of 6.5 m aperture. The 200 m diameter array will be located within 1/2° (15 km) of a lunar pole on approximately level ground, with a perimeter screen deployed to provide shade and cooling to cryogenic temperature. The 500 m diameter screen will allow unobscured access down to 8° elevation. All 18 telescopes will reflect light into a central beam combiner to form a single image covering wavelengths from 0.4 µm to 10 µm. The initial instrument complement will include high-resolution and multi-object spectrographs to exploit the single combined field of view of two arcminute diameter, with the diffraction limited resolution of 6.5 m aperture. Scientific applications include the search for molecular biosignatures in transiting exoplanets, and the study of galaxy evolution using red-shifted spectra to beyond z = 10. The array cost, including delivery to the Moon by SpaceX Starship for installation using lunar base infrastructure, is around $10 billion, similar to that of the 25 m2 JWST. To test the concept, first a single prototype 6.5 m unit would be operated at the lunar south pole. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades (part 2)'. [ABSTRACT FROM AUTHOR]

Cosmological and exoplanetary science using transformative telescopes like the ELT will demand precise calibration of astrophysical spectrographs in the blue-green, where stellar absorption lines are most abundant. Astrocombs—lasers providing a broadband sequence of regularly-spaced optical frequencies on a multi-GHz grid—promise an atomically-traceable calibration scale, but their realization in the blue-green is challenging for current infrared-laser-based technology. Here, we introduce a concept achieving a broad, continuous spectrum by combining second-harmonic generation and sum-frequency-mixing in an MgO:PPLN waveguide to generate 390–520 nm light from a 1 GHz Ti:sapphire frequency comb. Using a Fabry-Pérot filter, we extract a 30 GHz sub-comb spanning 392–472 nm, visualizing its thousands of modes on a high-resolution spectrograph. Experimental data and simulations demonstrate how the approach can bridge the spectral gap present in second-harmonic-only conversion. Requiring only ≈ 100 pJ pulses, our concept establishes a new route to broadband UV-visible generation at GHz repetition rates. Astrocombs serve as precision calibrators for astrophysical spectrographs by providing a regular sequence of optical lines on a multi-GHz grid. Here, the authors report the first broadband astrocomb in the UV to blue-green spectral region, where stellar absorption lines are most abundant. [ABSTRACT FROM AUTHOR]

We present a description and status of the first‐generation science instruments for the Giant Magellan Telescope (GMT), and the current plans for their scientific detectors. The first‐generation suite includes two visible (G‐CLEF and GMACS) and two infrared (GMTNIRS and GMTIFS) instruments, which will deliver data from wide‐band imaging to R 200,000 spectroscopy, with a combined spectral coverage from 300 nm to 5 μ$$ \mu $$m. All four instruments are designed for use with diffraction‐limited or ground‐layer adaptive optics modes. G‐CLEF is already in fabrication, while the other three are still in preliminary design. The first‐generation suite also includes a robotic fiber‐feed system called MANIFEST, which enables spectroscopy on objects anywhere in the 20 arcmin field of view of the telescope with custom fibers for G‐CLEF and GMACS. An additional facility instrument, GMagAO‐X, is being developed to provide high‐contrast imaging at visible and near‐infrared wavelengths. We also discuss the cameras that will be used for alignment, verification, and commissioning of the active and adaptive optics modes of the telescope and enable early science activities: ComCam and AOTC. [ABSTRACT FROM AUTHOR]

The paper describes an improved spectrograph of the Cassegrain focus of the 2-meter ShAO reflector using a CCD camera. The classic Universal Astro Grid Spectrograph (UAGS) was adapted to use the Andor CCD camera to obtain spectra of objects with low brightness in the range of 3600–8000 Å. A spectrograph with a diffraction grating of 651 lines/mm makes it possible to obtain the spectra of stars on the 2‑m ShAO telescope up to 18 mag with the resolution R = 1200, with a signal-to-noise ratio of about 50 for half an hour of exposure. The maximum allowable resolution is R = 3400 with binning 1 × 1. The complex can be used for observations of various types of transient objects, variable stars, and extragalactic objects. [ABSTRACT FROM AUTHOR]

We explain the details of the photometric operation mode of the ASTRONICAM near-IR spectrograph camera mounted on the 2.5-m telescope of the Caucasian Mountain Observatory of the Sternberg Astronomical Institute and describe algorithms used for primary correction and overall pipeline reduction of the acquired data. We present the transformation equations from the 2MASS photometric system to the instrumental -band system. We derive color transformation coefficients between the instrumental photometric system and standard MKO-NIR (Mauna Kea Observatories Near-Infrared) system for the , , and -band filters and show that the camera system is close to the standard photometric system. We found that in the case of observations at zenith, average background brightness level, and seeing the stars with , , can be measured with a 3000-s exposure at the signal-to-noise ratio . [ABSTRACT FROM AUTHOR]

We performed photometric observations of the S 255, S 257, S 140, NGC 7358, and the Orion Bar photo-dissociation regions (PDRs) at 2 m using narrow-band filters centered on the Br , H , and [Fe II] lines, as well as the narrow-band and the broad-band filters for continuum subtraction. The observations were done with the 2.5-m telescope of the SAI Caucasian Mountain Observatory and the near-infrared camera and spectrograph ASTRONIRCAM. We find several high-density arc-like structures in the Br and [Fe II] images of the ionized gas in NGC 7538 and extended shells and arcs visible through the H emission. The H ionization front and H dissociation front are merged in NGC 7538. In S 255 and S 257 we detected only Br emission from the H II regions and bright H emission from the PDRs. The projected distance between the H ionization and H dissociation fronts is approximately 0.3–0.4 pc, which cannot be explained using models of a uniform medium. Most probably, the ionized and neutral gas in these PDRs is clumpy. The H I-to-H transitions in the NGC 7538, S 255, S 257 and S 140 PDRs are gradual with no sharp borders. This conclusion also agrees with the suggestion of a clumpy medium. [ABSTRACT FROM AUTHOR]

The results of the analysis of photometric and spectral monitorings of the recurrent symbiotic nova T CrB, carried out using the low-resolution spectrograph TDS of the 2.5-m telescope and the CCD photometer of the 0.6-m telescope of the CMO SAI, are presented. It is shown that the fluxes in the emission lines H , H , He I 5876 change by 6–16 , and in the emission line He II 4686 by about 60 on timescales of 20–60 minutes. The line flux curves on August 25, 2020 are similar to the light curve of T CrB, but with a time delay of up to 600 s for different lines. The observed spectrum is approximated by the radiation of the system components with the following parameters: a red giant of spectral type M4 III, a nebula with K and emission measure of cm , and the accretion disk with , (at inclination ). [ABSTRACT FROM AUTHOR]

Focal Ratio Degradation (FRD) in optical fibres can result in light loss. In astronomical instrumentation, FRD must be controlled because light levels are low. A new Integral Field Spectrograph (IFS) instrument called Hector, was recently completed and was installed on the Anglo-Australian Telescope (AAT) in Australia in 2021 December. The integral field units (IFUs) for Hector made with hexagonally packed multi-mode fibres are called hexabundles. In this paper, we introduce a cone-beam measurement method to measure FRD at optical wavelengths. We present the FRD and throughput performance of the hexabundles for Hector and show that the process for making hexabundles introduced no additional significant FRD beyond that of the bare fibre. [ABSTRACT FROM AUTHOR]

We present an estimation and analysis of Near Infrared (NIR) background for the astronomical site at Mount Abu. Mount Abu Observatory is situated at Gurushikhar, Rajasthan, India, operated by the Physical Research Laboratory. Data obtained from the NIR observations of various sources using the Near Infrared Camera/Spectrograph (NICS) on the 1.2-m telescope are used to derive the NIR background estimates. We notice seasonal variations in these values, with the summer months showing brighter background compared to the winter. We also present a comparison of synthetic atmospheric transmission at Mount Abu with other Indian observatories at various altitudes. We identify the plausible contributors to the NIR background in our observations and discuss the potential ones that can contribute to the noticed seasonal variations. Overall, we found that the NIR background does not show any systematic variation over the period of observations from 2010 to 2019. The results reported here are specific to the NICS instrument on the 1.2-m telescope. [ABSTRACT FROM AUTHOR]

We report the results of long-term reverberation mapping campaigns of the nearby active galactic nuclei (AGNs) NGC 4151, spanning from 1994 to 2022, based on archived observations of the FAST Spectrograph Publicly Archived Programs and our new observations with the 2.3 m telescope at the Wyoming Infrared Observatory. We reduce and calibrate all the spectra in a consistent way, and derive light curves of the broad H β line and 5100 Å continuum. Continuum light curves are also constructed using public archival photometric data to increase sampling cadences. We subtract the host galaxy contamination using Hubble Space Telescope imaging to correct fluxes of the calibrated light curves. Utilizing the long-term archival photometric data, we complete the absolute flux-calibration of the AGN continuum. We find that the H β time delays are correlated with the 5100 Å luminosities as |$\tau _{\rm H\beta }\propto L_{5100}^{0.46\pm 0.16}$|⁠. This is remarkably consistent with Bentz et al. (2013)'s global size–luminosity relationship of AGNs. Moreover, the data sets for five of the seasons allow us to obtain the velocity-resolved delays of the H β line, showing diverse structures (outflows, inflows, and discs). Combining our results with previous independent measurements, we find the measured dynamics of the H β broad-line region (BLR) are possibly related to the long-term trend of the luminosity. There is also a possible additional ∼1.86 yr time lag between the variation in BLR radius and luminosity. These results suggest that dynamical changes in the BLR may be driven by the effects of radiation pressure. [ABSTRACT FROM AUTHOR]

A modular cryogenic cross-disperser MOBIUS for the Large Binocular Telescope (LBT) is being developed to produce a simultaneous zJHK spectrum with a single LUCI, the LBT Utility Cameras in the Infrared. Its compact and exchangeable optical design fit within the existing focal plane mask frame of the LUCI spectrograph without any other hardware modifications. This unique deployable system enables a rapid acquisition of data over a wide wavelength range to better understand the unknown objects in the universe. [ABSTRACT FROM AUTHOR]

Context. Hyperactive comets are a small group of comets whose activity is higher than expected. They seem to emit more water than would normally be expected given the size of their nucleus. Comet 46P/Wirtanen (hereafter, 46P) is among these objects of interest. Investigating its activity and composition evolution could provide clues about its origins and its formation region in the Solar nebulae. Aims. Given the exceptional close approach of comet 46P to the Earth in 2018, we aim to study the evolution of its activity and composition as a function of heliocentric distances before and after perihelion. Methods. We used both TRAPPIST telescopes to monitor the comet for almost a year with broad and narrow-band filters. We derived the production rates of five gaseous species (OH, NH, CN, C3, and C2) using a Haser model as well as the A(θ)fρ dust proxy parameter. The comet was also observed with the two optical high-resolution spectrographs UVES and ESPRESSO, mounted on the 8-m ESO VLT, to measure the isotopic ratios of C and N, along with the oxygen forbidden-line ratios and the NH2 ortho-to-para ratios. Results. Over nearly a year, we followed the rise and decline of the production rates of different species as well as the dust activity of 46P on both pre- and post-perihelion. Relative abundances with respect to CN and OH along the orbit of the comet show constant and symmetric abundance ratios and a typical coma composition. We determined the rotation period of the nucleus using high-cadence observations and long series of CN images on several nights. We obtained a value of (9.18±0.05) hours at perihelion. Using the high-resolution spectra of 46P coma, we derived C and N isotopic ratios of 100±20 and 150±30 as well as a green-to-red forbidden oxygen [OI] line ratio of 0.23±0.02. We measured a NH2 ortho-to-para ratio of 3.31 ±0.03 and derived an ammonia ratio of 1.19±0.03, corresponding to a spin temperature of 27±1 K. Conclusions. Narrow-band observations show that comet 46P is a hyperactive comet for which 40% of its nucleus surface is active. It has a typical composition, similar to other normal comets; however, an asymmetric behavior with respect to perihelion has been seen in its activity, which is typical of seasonal effects. Photometric measurements show no evidence for a change in the rotation period of the nucleus during this apparition. High-resolution spectra show that 46P has typical NH2 ortho-to-para, [OI] lines ratios, and C and N isotopic ratios. [ABSTRACT FROM AUTHOR]

Magnetic chemically peculiar stars of the main sequence can present rotational periods as long as many decades. Here we report the results of an observational campaign started in 2001 aimed at establishing these very long periods from the variability of the integrated magnetic field modulus, the so-called surface magnetic field B s, as measured from the Zeeman splitting of the Fe  ii  6149.258 Å spectral line. 36 stars have been monitored with various high-resolution spectrographs at different telescopes, totalling 412 newly collected spectra. To improve the phase coverage, we have also exploited all public archives containing high-resolution spectra, many not yet published. On the basis of these new B s variability curves, we (1) confirm or revisit the periods of 24 stars, (2) extend the lower limits to the periods of HD 55719 (P > 38 yr), HD 165474 (P > 27 yr), and HD 177765 (P > 37 yr), (3) establish for the first time the periods of HD 29578 (P  = 10.95 yr), HD 47103 (P  = 17.683 d), HD 150562 (P  = 5.7 yr), and HD 216018 (P  = 34.044 d), and (4) set lower limits to the periods of HD 75445 (P »14 yr), HD 110066 (P » 29 yr), HD 116114 (P > 48 yr), and HD 137949 (P > 27 yr). As to γ Equ, whose period must exceed 90 yr, we point out a clear decrease in the field modulus, the maximum of which coincides within the uncertainties with the minimum of the variation in the integrated longitudinal field. [ABSTRACT FROM AUTHOR]

We present a new study of the Algol-type eclipsing binary system AS Eri based on the combination of the MOST and TESS light curves and a collection of very precise radial velocities obtained with the spectrographs HERMES operating at the Mercator telescope, La Palma, and TCES operating at the Alfred Jensch telescope, Tautenburg. The primary component is an A3 V-type pulsating, mass-accreting star. We fitted the light and velocity data with the package phoebe , and determined the best-fitting model adopting the configuration of a semi-detached system. The orbital period has been improved using a recent (O-C) analysis and the phase shift detected between both light curves to the value 2.6641496 ± 0.0000001 d. The absence of any cyclic variation in the (O-C) residuals confirms the long-term stability of the orbital period. Furthermore, we show that the models derived for each light curve separately entail small differences, e.g. in the temperature parameter T eff,2. The high quality of the new solutions is illustrated by the residuals. We obtained the following absolute component parameters: L 1  = 14.125 L⊙, M 1  = 2.014 M⊙, R 1  = 1.733 R⊙, log g1  = 4.264, L 2  = 4.345 L⊙, M 2  = 0.211 M⊙, R 2  = 2.19 R⊙, log g2  = 3.078  with T eff,2/ T eff,1  = 0.662 ± 0.002. Although the orbital period appears to be stable on the long term, we show that the light-curve shape is affected by a years-long modulation which is most probably due to the magnetic activity of the cool companion. [ABSTRACT FROM AUTHOR]

The low-frequency component of the distortions caused by both the atmospheric turbulence and the behavior of the telescope itself has been studied. A corrector for the position of the center of the star image has been developed and is being used in front of the high-resolution Echelle spectrograph on the 6 m telescope of the Special Astrophysical Observatory, Russian Academy of Sciences. To speed up the calculations and to increase the bandwidth, a laser beam angular stabilization system based on an FPGA platform is considered. The system consists of two tip-tilt mirrors and two quadrant photodiodes. The FPGA analyzes the signals from the photodiodes, calculates and then applies the voltages to the piezo-driven tip-tilt mirrors to minimize the displacement of the beam on the photodiodes. The stabilization system was developed as a part of the adaptive optical system to improve the efficiency of the high-resolution Echelle spectrograph. [ABSTRACT FROM AUTHOR]

We provide here tables of stellar limb-darkening coefficients (LDCs) for the Ariel ESA M4 space mission. These tables include LDCs corresponding to different wavelength bins and white bands for the NIRSpec, AIRS-Ch0 and AIRS-Ch1 spectrographs, and those corresponding to the VISPhot, FGS1 and FGS2 photometers. The LDCs are calculated with the open-source software ExoTETHyS for three complete grids of stellar atmosphere models obtained with the ATLAS9 and PHOENIX codes. The three model grids are complementary, as the PHOENIX code adopts more modern input physics and spherical geometry, while the models calculated with ATLAS9 cover wider ranges of stellar parameters. The LDCs obtained from corresponding models in the ATLAS9 and PHOENIX grids are compared in the main text. All together the models cover the following ranges in effective temperature (1500K ≤ Teff ≤ 50000K), surface gravity (0.0 dex ≤ log g ≤ 6.0 dex), and metallicity (− 5.0 ≤ [M/H] ≤ 1.0). [ABSTRACT FROM AUTHOR]

Abstract—Over the past two decades NES spectrograph attached to the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences was used to perform spectroscopy of stars at advanced stages of evolution spanning a wide range of masses. The studies cover a variety of star types with high mass-loss rates during the preceding and current stages of evolution. All these stars have extended atmospheres and structured circumstellar envelopes produced by strong stellar winds. We have studied luminous blue variables (LBVs) near the Eddington limit; hot supergiants exhibiting B[e] phenomenon, which are very likely intermediate-mass binary systems soon after the fast mass exchange stage; a group of yellow hypergiants, as well as an extensive sample of low-mass post-AGB supergiants. The diverse nature of the types of these stars whose common feature is the presence of a envelope makes the spectroscopy of such objects a comprehensive task. Such studies consist of many etapes, which include not only determining the specifics of the chemical composition and understanding the role of supergiants in the enrichment of the interstellar medium with freshly synthesized elements, but also the determination of the evolutionary stage of the objects considered, as well as search for and analysis of spectroscopic manifestations of kinematic processes in their extended and unstable atmospheres and gas-dust envelopes. We spectroscopically monitored selected objects to study in detail the instability of the kinematic state of the atmospheres of the stars considered. Studies of stars at neighboring evolutionary stages have been initiated. This review reports the most significant observational obtained within the framework of the – programs. [ABSTRACT FROM AUTHOR]

We discuss the results of our spectroscopy for 17 candidates for distant quasars selected by the SRGz classification system based on data from the first and second sky surveys with the eROSITA telescope onboard the SRG X-ray observatory. Most of the quasar candidates were selected within the DaLeQo observing program, whose goal is a search for the most X-ray luminous quasars with luminosities erg s at redshifts . Our spectroscopic observations were carried out at the 6-m BTA telescope with the SCORPIO-2 spectrograph. We have managed to confirm eight new X-ray quasars at , including the quasar SRGe J020142.8-015347 at . Owing to the large diameter of the BTA mirror and the high quantum efficiency of the SCORPIO-2 spectrograph in the range 6000–9000 Å, we have managed to measure the С IV (1549 Å) line parameters and to estimate the supermassive black hole masses and accretion rates for seven quasars. [ABSTRACT FROM AUTHOR]

We present the first measurement of the metallicity gradient in extremely metal-poor galaxies (EMPGs). With Subaru/Faint Object Camera And Spectrograph (FOCAS) Integral Field Unit (IFU), we have observed a nearby, low-mass EMPG, HSC J1631+4426, whose oxygen abundance and stellar mass are known to be 12 + log (O/H) = 6.9 and log10(M */ M ⊙) = 5.8, respectively. The measured metallicity gradient is −0.36 ± 0.04 dex kpc−1 corresponding to −0.049 ± 0.006 dex |$\:R_\mathrm{e}^{-1}$| for the continuum effective radius of R e = 0.14 kpc. Our observation has successfully demonstrated that three-dimensional spectroscopy with 8 m-class telescopes is powerful enough to reveal the metallicity distribution in local EMPGs, providing precious information on the baryon cycle in local analogs of primordial galaxies in the early Universe. [ABSTRACT FROM AUTHOR]

Much of the progress in astronomy has been driven by instrumental developments, from the first telescopes to fiber fed spectrographs. In this review, we describe the field of astrophotonics, a combination of photonics and astronomical instrumentation that is gaining importance in the development of current and future instrumentation. We begin with the science cases that have been identified as possibly benefiting from astrophotonic devices. We then discuss devices, methods and developments in the field along with the advantages they provide. We conclude by describing possible future perspectives in the field and their influence on astronomy. [ABSTRACT FROM AUTHOR]

We discuss the detection of 14 rovibrational lines of CH+, obtained toward the planetary nebula NGC 7027 with the iSHELL spectrograph on NASA's Infrared Telescope Facility (IRTF) on Maunakea. Our observations in the 3.49–4.13 μm spectral region, obtained with a 0.″375 slit width that provided a spectral resolving power λ/Δλ ∼ 80,000, have resulted in the unequivocal detection of the R(0)−R(3) and P(1)−P(10) transitions within the v = 1−0 band of CH+. The R-branch transitions are anomalously weak relative to the P-branch transitions, a behavior that is explained accurately by rovibronic calculations of the transition dipole moment reported in a companion paper. Nine infrared transitions of H2 were also detected in these observations, comprising the S(8), S(9), S(13), and S(15) pure rotational lines; the v = 1−0 O(4)−O(7) lines; and the v = 2−1 O(5) line. We present a photodissociation model, constrained by the CH+ and H2 line fluxes that we measured, that includes a detailed treatment of the excitation of CH+ by inelastic collisions, optical pumping, and chemical ("formation") pumping. The latter process is found to dominate the excitation of the observed rovibrational lines of CH+, and the model is remarkably successful in explaining both the absolute and relative strengths of the CH+ and H2 lines. [ABSTRACT FROM AUTHOR]

We present the results of spectroscopic follow-up for 1897 low-metallicity star candidates, selected from the Best & Brightest (B&B) Survey, carried out with the GMOS-N/S (Gemini North/South telescopes) and Goodman (SOAR Telescope) spectrographs. From these low-resolution (R ∼ 2000) spectra, we estimate stellar atmospheric parameters, as well as carbon and magnesium abundance ratios. We confirm that 56% of our program stars are metal-poor ([Fe/H] < − 1.0), 30% are very metal-poor (VMP; [Fe/H] < − 2.0), and 2% are extremely metal-poor (EMP; [Fe/H] < − 3.0). There are 191 carbon-enhanced metal-poor (CEMP) stars, resulting in CEMP fractions of 19% and 43% for the VMP and EMP regimes, respectively. A total of 94 confirmed CEMP stars belong to Group I (A(C) ≳ 7.25) and 97 to Group II (A(C) ≲ 7.25) in the Yoon–Beers A(C)−[Fe/H] diagram. Moreover, we combine these data with Gaia EDR3 astrometric information to delineate new target-selection criteria, which have been applied to the Goodman/SOAR candidates, to more than double the efficiency for identification of bona fide VMP and EMP stars in comparison to random draws from the B&B catalog. We demonstrate that this target-selection approach can achieve success rates of 96%, 76%, 28%, and 4% for [Fe/H] ≤ − 1.5, ≤ − 2.0, ≤ − 2.5 and ≤ − 3.0, respectively. Finally, we investigate the presence of dynamically interesting stars in our sample. We find that several VMP/EMP ([Fe/H] ≤ − 2.5) stars can be associated with either the disk system or halo substructures like Gaia-Sausage/Enceladus and Sequoia. [ABSTRACT FROM AUTHOR]

Mt. Abu Faint Object Spectrograph and Camera – Pathfinder (MFOSC-P) is an imager-spectrograph developed for the Physical Research Laboratory (PRL) 1.2m telescope at Gurushikhar, Mt. Abu, India. MFOSC-P is based on a focal reducer concept and provides seeing limited imaging (with a sampling of 3.3 pixels per arc-second) in Bessell's B, V, R, I and narrow-band H-α filters. The instrument uses three plane reflection gratings, covering the spectral range of 4500-8500Å, with three different resolutions of 500, 1000, and 2000 around their central wavelengths. MFOSC-P was conceived as a pathfinder instrument for a next-generation instrument on the PRL's 2.5m telescope which is coming up at Mt. Abu. The instrument was developed during 2015-2019 and successfully commissioned on the PRL 1.2m telescope in February 2019. The designed performance has been verified with laboratory characterization tests and on-sky commissioning observations. Different science programs covering a range of objects are being executed with MFOSC-P since then, e.g., spectroscopy of M-dwarfs, novae & symbiotic systems, and detection of H-α emission in star-forming regions. MFOSC-P presents a novel design and cost-effective way to develop a FOSC (Faint Object Spectrograph and Camera) type of instrument on a shorter time-scale of development. The design and development methodology presented here is most suitable in helping the small aperture telescope community develop such a versatile instrument, thereby diversifying the science programs of such observatories. [ABSTRACT FROM AUTHOR]

The Near-Infrared High Throughput Spectrograph (NIHTS) is in operation on the 4.3 m Lowell Discovery Telescope (LDT) in Happy Jack, AZ. NIHTS is a low-resolution spectrograph (R ∼ 200) that operates from 0.86 to 2.45 microns. NIHTS is fed by a custom dichroic mirror which reflects near-infrared wavelengths to the spectrograph and transmits the visible to enable simultaneous imaging with the Large Monolithic Imager (LMI), an independent visible wavelength camera. The combination of premier tracking and acquisition capabilities of the LDT, a several arcminutes field of view on LMI, and high spectral throughput on NIHTS enables novel studies of a number of astrophysical and planetary objects including Kuiper Belt Objects, asteroids, comets, low mass stars, and exoplanet hosts stars. We present a summary of NIHTS operations, commissioning, data reduction procedures with two approaches for the correction of telluric absorption features, and an overview of select science cases that will be pursued by Lowell Observatory, Northern Arizona University, and LDT partners. [ABSTRACT FROM AUTHOR]

Spectroscopy in the visible and near-infrared has been the main tool for characterising the surface properties of asteroids for decades. For a given target, the two wavelength regimes are usually acquired by different telescopes/instruments, separated by years. They are seldom obtained simultaneously. However, it is not straightforward to combine datasets from different sources because of the spectral reddening linked with phase angle. We present the first-light result of SOVAG (Spectrographe pour l'Observations dans le Visible et infrarouge proche d'Astéroïdes Géocroiseurs), a new concept of spectrograph for observing both wavelength ranges at the same time. It is compact in design and portable. We developed a prototype of this instrument between 2016 and 2018. In July 2018, we mounted SOVAG on the 1 m-telescope in Pic du Midi observatory (for which it was designed) and conducted its on-sky first light experiment. We present a spectrum of (4) Vesta which demonstrates the reliability of observations and the accuracy of the calibration. Ongoing development will allow us to push observation-limits toward fainter objects. [ABSTRACT FROM AUTHOR]

A 20 m space telescope is described with an unvignetted 1° field of view—a hundred times larger in area than fields of existing space telescopes. Its diffraction-limited images are a hundred times sharper than from wide-field ground-based telescopes and extend over much if not all the field, 40 arcmin diameter at 500 nm wavelength, for example. The optical system yielding a 1°, 1.36 m diameter image at f/3.9 has relatively small central obscuration, 9% by area on axis, and is fully baffled. Several carousel-mounted instruments can each access directly the full image. The initial instrument complement includes a 400 gigapixel silicon imager with 2 µm pixels (0.005 arcsec), and a 60 gigapixel HgCdTe imager with 5 µm pixels (0.012 arcsec). A multi-object spectrograph with 10 000 fibres will allow spectroscopy with 0.02 arcsec resolution. Direct imaging and spectroscopy of exoplanets can take advantage of the un-aberrated, on-axis image (5 nm RMS wavefront error). While this telescope could be built for operation in free space, a site accessible to a human outpost at the Moon's south pole would be advantageous, for assembly and repairs. The lunar site would allow also for the installation of new instruments to keep up with evolving scientific priorities and advancing technology. Cooling to less than 100E K would be achieved with a surrounding cylindrical thermal shield. [ABSTRACT FROM AUTHOR]

Multi-object spectroscopy has become a valuable technique in numerous modern astronomical facilities. Most spectrographs have thousands of fibre positioners packed at a focal plane with shared working space. Therefore, positioners might collide with each other, which can lead to them being damaged. In this study, we first analysed the types of collisions between hexagonal patterned theta–phi positioners and the possibility of these collisions. Based on this, we proposed a motion planning method by deploying a proposed 'safety zone' within the positioner patrol area. Simulated experiments validated that our method could completely solve collisions between positioners with equal arms, such as the Large-sky-Area Multi-Object fibre Spectroscopic Telescope (LAMOST) and the Dark Energy Spectroscopic Instrument (DESI), or between positioners with unequal arms, such as the Multi-Object Optical and Near-infrared Spectrograph (MOONS). [ABSTRACT FROM AUTHOR]

The Transient Double-beam Spectrograph (TDS) is designed for low-spectral-resolution optical observations of nonstationary and extragalactic sources at the 2.5-m telescope of the Caucasus Mountain Observatory (CMO) of SAI MSU. The spectra are recorded simultaneously in two channels, short-wavelength (360–577 nm, reciprocal dispersion 1.21 Å/pixel, resolution with a -wide working slit) and long-wavelength (567–746 nm, 0.87 Å/pixel, ) ones, with the light between them being split by a dichroic mirror with a 50 transmittance at 574 nm. In the "blue" channel, it is possible to automatically replace the main grating by an additional one with a double resolving power. Two CCD cameras based on E2V 42-10 detectors cooled down to C with a readout noise of 3 electrons at a readout rate of 50 kHz serve as detectors. The height of the entrance slit is 3 arcmin. The spectrograph incorporates a back-slit viewing camera and a calibration unit to record the line spectrum of a gas-discharge lamp and a continuum LED source ("flat field") to take into account the vignetting and slit width nonuniformity. The transmittance of the entire optical path without losses on the slit at the zenith is 20 and 35 in the "blue" and "red" channels, respectively. Excluding the atmosphere and the telescope, the efficiency of the TDS itself reaches 47 and 65 at maximum, respectively. The spectrograph is permanently mounted at the Cassegrain focus of the 2.5-m CMO SAI MSU telescope together with a wide-field photometric CCD-camera; the light is fed into the spectrograph by a flat diagonal mirror inserted into the optical path. Regular observations of nonstationary stars and extragalactic sources to with a signal-to-noise ratio above 5 in 2 h of observations have been carried out with the TDS since November 2019. [ABSTRACT FROM AUTHOR]

We present a new analysis of the multiple-star V1200 Centauri based on the most recent observations for this system. We used the photometric observations from the Solaris network and the Transiting Exoplanet Survey Satellite telescope, combined with the new radial velocities from the CHIRON spectrograph and those published in the literature. We confirmed that V1200 Cen consists of a 2.5-d eclipsing binary orbited by a third body. We derived the parameters of the eclipsing components, which are |$M_{\mathrm{ Aa}} = 1.393\pm 0.018\,$| M⊙, |$R_{\mathrm{ Aa}} = 1.407\pm 0.014\,$| R⊙, and |$T_{{\rm eff},\mathrm{ Aa}} = 6588\pm 58\,$| K for the primary, and |$M_{\mathrm{ Ab}} = 0.8633\pm 0.0081\,$| M⊙, |$R_{\mathrm{ Ab}} = 1.154\pm 0.014\,$| R⊙, and |$T_{{\rm eff},\mathrm{ Ab}} = 4475\pm 68\,$| K for the secondary. Regarding the third body, we obtained significantly different results than those previously published. The period of the outer orbit is found to be 180.4 d, implying a minimum mass of |$M_\mathrm{ B} = 0.871\pm 0.020\,$| M⊙. Thus, we argue that V1200 Cen is a quadruple system with a secondary pair composed of two low-mass stars. Finally, we determined the ages of each eclipsing component using two evolution codes, namely mesa and cestam. We obtained ages of 16–18.5 and 5.5–7 Myr for the primary and the secondary, respectively. In particular, the secondary appears larger and hotter than that predicted at the age of the primary. We concluded that dynamical and tidal interactions occurring in multiples may alter the stellar properties and explain the apparent non-coevality of V1200 Centauri. [ABSTRACT FROM AUTHOR]

Typically large telescope construction and operation costs scale up faster than their collecting area. This slows scientific progress, making it expensive and complicated to increase telescope size. We review the argument that a metric that represents the capability of an imaging survey telescopes, and that captures a wide range of science objectives, is the telescope grasp—the amount of volume of space in which a standard candle is detectable per unit time. We show that in a homogeneous Euclidean universe, and in the background-noise dominated limit, the grasp is: , where Ω is the telescope field of view, Aeff is the effective collecting area of the telescope, σ is the instrumental or atmospheric seeing or the pixel-size, whichever dominates, tE is the exposure time, and tD is the dead time. In this case, the optimal exposure time is three times the dead time. We also introduce a related metric we call the information-content grasp, which summarizes the variance of all sources observed by the telescope per unit time. We show that, in the background-noise dominated regime, the information-content grasp scales like the grasp. For seeing-dominated sky surveys, in terms of grasp, étendue, or collecting-area optimization, recent technological advancements make it more cost effective to construct multiple small telescopes rather than a single large telescope with a similar grasp or étendue. Among these key advancements are the availability of large-format back-side illuminated CMOS detectors with ≲4 μm pixels, well suited to sample standard seeing conditions given typical focal lengths of small fast telescopes. We also discuss the possible use of multiple small telescopes for spectroscopy and intensity interferometers. We argue that if all the obstacles to implementing cost-effective wide-field imaging and multi-object spectrographs using multiple small telescopes are removed, then the motivation to build new single large-aperture (≳1 m) visible-light telescopes which are seeing-dominated, will be weakened. These ideas have led to the concept of the, currently under construction, Large-Array Survey Telescope. [ABSTRACT FROM AUTHOR]

Abstract—We briefly discuss the stages of the development of high-resolution spectroscopy methods used with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, which are related to the problem considered. We consider the possibility of the multiple increase of the stellar spectroscopy efficiency as a result of application of state-of-the-art solutions in the field of adaptive optics. At the first stage, we plan to perform tasks involving the image control and correction based on the central star. This stage should be naturally started with a spectrograph with the highest spectral resolution where the relatively bright star studied can serve as the reference source in the method of adaptive optics. [ABSTRACT FROM AUTHOR]

The Faint Intergalactic Medium Redshifted Emission Balloon (FIREBall) is a mission designed to observe faint emission from the circumgalactic medium of moderate-redshift (z ∼ 0.7) galaxies for the first time. FIREBall observes a component of galaxies that plays a key role in how galaxies form and evolve, likely contains a significant amount of baryons, and has only recently been observed at higher redshifts in the visible. Here we report on the 2018 flight of the FIREBall-2 Balloon telescope, which occurred on 2018 September 22 from Fort Sumner, New Mexico. The flight was the culmination of a complete redesign of the spectrograph from the original FIREBall fiber-fed integral field unit to a wide-field multiobject spectrograph. The flight was terminated early owing to a hole in the balloon, and our original science objectives were not achieved. The overall sensitivity of the instrument and telescope was 90,000 LU, due primarily to increased noise from stray light. We discuss the design of the FIREBall-2 spectrograph, including modifications from the original FIREBall payload, and provide an overview of the performance of all systems. We were able to successfully flight-test a new pointing control system, a UV-optimized, delta-doped, and coated electron multiplying CCD, and an aspheric grating. The FIREBall-2 team is rebuilding the payload for another flight attempt in the fall of 2021, delayed from 2020 as a result of COVID-19. [ABSTRACT FROM AUTHOR]

We have carried out observations of a peculiar comet, C/2016 R2 (Pan-STARRS), using a low-resolution spectrograph mounted on the 1.2-m telescope at Mount Abu Infrared Observatory, India. The comet was observed on two dates in 2018 January, when it was at a heliocentric distance of 2.8 au. A study based on our observations has revealed that the optical spectrum of this comet is quite unusual compared with general cometary spectra. Most major cometary emissions, such as C2, C3 and CN, were absent in comet C/2016 R2. However, the comet's spectrum showed very strong emission bands from ionic species such as CO+ and N |$_{2}^{+}$|⁠. A mean N2/CO ratio of 0.09 ± 0.02 was derived from the spectra and an extremely low depletion factor of 1.6 ± 0.4 has been estimated for this ratio compared with the solar nebula. We have also detected minor emission features beyond 5400 Å, albeit marginally. The column densities of CO+ and N |$_{2}^{+}$| were calculated from their emission bands. The optical spectrum suggests that the cometary ice is dominated by CO. The low depletion factor of the N2/CO ratio in this comet, compared with the solar nebula, and the unusual spectrum of the comet are consequences of distinctive processing at the location of its formation in the early solar nebula. [ABSTRACT FROM AUTHOR]

Abstract—The paper presents complete results of measurements of the magnetic-field longitudinal component Be and radial velocities VR for 163 objects, mainly main-sequence chemically peculiar stars and standards. Observations were carried out in 2012 at the 6-m BTA telescope using the Main Stellar Spectrograph (MSS) equipped with a Zeeman analyzer. Six new chemically peculiar magnetic stars were discovered: HD84 882, HD109 030, HD170 054, HD189 775, HD341 037, and BD + 61°2436. The observations were carried out during 18 nights, 560 circularly-polarizedspectra were detected. New data were obtained for 120 magnetic stars (including 5 standard stars) and 43 non-magnetic stars (including nine standard stars). The radial velocities of all objects were measured; for 46 stars, they were obtained for the first time. Observations of standard magnetic and non-magnetic stars confirm the absence of any significant systematic errors capable of introducing distortions into the measurement results of Be. The paper provides comments on the research results for each of 163 stars. [ABSTRACT FROM AUTHOR]

Abstract—This work is a continuation of the studies of the ultrafast variability of line profiles in the spectra of early-type stars. Line profile variations in the spectrum a chemically peculiar A0Vp star α2 CVn are investigated using the January 6, 2020 observations carried out with the 6-meter BTA telescope at SAO RAS equipped with the MSS spectrograph. Regular short-term periodic variations of the Hβ, FeII, and CrII lines were detected with periods ranging from 4 to 140 minutes. The magnetic field of the star was determined for all observations. The average measured longitudinal magnetic field component over the entire duration of observations is about 600 G, which is close to the value expected from the well-known magnetic field phase curve. [ABSTRACT FROM AUTHOR]

We report the detection of emission in the v = 1 − 0 P(1) (3.51629 μm) and P(2) (3.60776 μm) rovibrational lines of the helium hydride cation (HeH+) from the planetary nebula NGC 7027. These detections were obtained with the iSHELL spectrograph on NASA's Infrared Telescope Facility on Maunakea. They confirm the discovery of HeH+ reported recently by Güsten et al., who used the GREAT instrument on the SOFIA airborne observatory to observe its pure rotational J = 1 − 0 transition at 149.137 μm. The flux measured for the HeH+v = 1 − 0 P(1) line is in good agreement with our model for the formation, destruction, and excitation of HeH+ in NGC 7027. The measured strength of the J = 1 − 0 pure rotational line, however, exceeds the model prediction significantly, as does that of the v = 1 − 0 P(2) line, by factors of 2.9 and 2.3 respectively. Possible causes of these discrepancies are discussed. Our observations of NGC 7027, covering the 3.26–3.93 μm spectral region, have led to the detection of more than 60 spectral lines including nine rovibrational emissions from CH+. The latter are detected for the first time in an astronomical source. [ABSTRACT FROM AUTHOR]

SuperSpec is an on-chip filter bank spectrometer designed for wideband moderate-resolution spectroscopy at millimeter wavelengths, employing TiN kinetic inductance detectors. SuperSpec technology will enable large-format spectroscopic integral field units suitable for high-redshift line intensity mapping and multi-object spectrographs. In previous results, we have demonstrated noise performance in individual detectors suitable for photon noise-limited ground-based observations at excellent mm-wave sites. In these proceedings, we present the noise performance of a full R ∼ 275 spectrometer measured using deployment-ready RF hardware and software. We report typical noise equivalent powers through the full device of ∼ 3 × 10 - 16 W Hz - 1 / 2 at expected sky loadings, which are photon noise dominated. Based on these results, we plan to deploy a six-spectrometer demonstration instrument to the Large Millimeter Telescope in early 2020. [ABSTRACT FROM AUTHOR]

Abstract—We report the results of laboratory tests of the first version of the high-resolution fiber-fed spectrograph designed for the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS). During laboratory tests a spectral resolution of about 70 000 was achieved. The peak efficiency of the entire optical path of the spectrograph (without light losses at the CCD, primary mirror of the 6-m telescope, and in the atmosphere) at 620 nm and with the equivalent slit widths of the 1″.5 and 0″.75 are equal to 8% and 4%, respectively. The resolving power R = 70 000 and 100 000 can be reached with the sky aperture 0″.75 and 0″.4 respectively. In the current version of the spectrograph these regimes of operation are implemented by mechanic aperturing of the slit. A dedicated projecting camera has been developed and is currently manufactured to operate with a collimated 200-mm diameter beam, which will make it possible to increase the spectral resolution up to 100 000. A two-beam image slicer will be used to maintain the luminous efficiency of the instrument at least at the 6% level. [ABSTRACT FROM AUTHOR]

The algorithm for the reduction of spectroscopic observations with the ASTRONIRCAM camera-spectrograph installed at the 2.5-m telescope of the Sternberg Astronomical Institute of the Moscow State University is described. The instrument allows spectra of astronomical objects with long () and short () slits to be taken in the wavelength range from 1 to 2.5 m. The measured resolution reaches for a slit; the light efficiency of the system changes from 6 to in the working wavelength range in the long-slit mode and from 1 to in the cross-dispersion mode. The transmission is limited by the quality of the grisms used. We have estimated the fraction of scattered light and studied the mechanical flexures and temperature drifts of the structure. [ABSTRACT FROM AUTHOR]

The results of ultrahigh-time-resolution ( s) observations of the B1 Iab supergiant Leo with the 1.25-m telescope at the Crimean Astronomical Station of the SAI MSU are presented. Regular line profile variations with periods of 15–30 min have been revealed. Significant changes in the average line profiles on time intervals of 1–3 days have been detected. Evidence for the existence of short-period line profile variations on time scales of 15–25 min is provided. The nature of the short-period line profile variations is discussed. The possibility of studying the fast variations in the profiles of broad lines (mostly the Balmer hydrogen and He I lines) using low-resolution spectrographs with at 1–2-m telescopes is pointed out. [ABSTRACT FROM AUTHOR]

CAFE is a high-resolution spectrograph with high-precision radial velocity capabilities mounted at the 2.2 m telescope of Calar Alto Observatory. It suffered from strong degradation after 4 yr of operations and it has now been upgraded. The upgrades of the instrument (now named CAFE2) aimed at recovering the throughput and improving the stability due to the installation of a new grating, an active temperature control in the isolated coudé room, and a new scrambling system. In this paper, we present the results of the new commissioning of the instrument and a new pipeline (CAFExtractor) that provides the user with fully reduced data including radial velocity measurements of FGK dwarf stars. The commissioning results show a clear improvement in the instrument performance. The room temperature is now stabilized down to 5 mK during one night and below 50 mK over two months. CAFE2 now provides 3 m s−1 precision on the reference ThAr frames and the on-sky tests provide a radial velocity precision of 8 m s−1 during one night (for S/N > 50). The throughput of the instrument is now back to nominal values with an efficiency of around 15 per cent at 550 nm. The limiting magnitude of the instrument for a 1 h exposure and S/N = 20 is V  = 15. With all these properties, CAFE enters into the small family of high-resolution spectrographs at 2–4 m telescopes capable of reaching radial velocity precisions below 10 m s−1. [ABSTRACT FROM AUTHOR]

An example of simultaneous spectroscopic redshift measurements for a large number of galaxies in a cluster by multiobject spectroscopy with the medium- and low-resolution TFOSC spectrograph at the RussianTurkish 1.5-m telescope (RTT150) is presented. The redshifts of galaxies in the cluster at detected previously by the SunyaevZeldovich signal in the Planck all-sky survey have been measured. The spectra of 16 cluster galaxies, 9 of which were determined as ellipticals, were taken in one observation with an exposure time of 3 h and high-quality redshift measurements were made for them. We show that the redshifts of galaxies with magnitudes to , whose number in the TFOSC field can reach dozens, depending on the cluster richness and distance, can be measured in one observation with the TFOSC spectrograph using multiobject masks. Such measurements may be required to refine the redshifts of clusters and to estimate their masses by the dynamical method. [ABSTRACT FROM AUTHOR]

High‐performance instruments at large ground‐based telescopes have made integral field spectroscopy (IFS) a powerful tool for the study of extended objects such as galaxies, nebulae, or even larger survey fields on the sky. Here, we discuss the capabilities of IFS for the study of resolved stellar populations, using the new method of point‐spread‐function‐fitting crowded field IFS, analogous to the well‐established technique of crowded field photometry with image sensors. We review early pioneering work with first‐generation integral field spectrographs, the breakthrough achieved with the multiunit spectral explorer (MUSE) instrument at the European Organisation for Astronomical Research in the Southern Hemisphere (ESO) Very Large Telescope, the remarkable progress accomplished with MUSE in the study of globular clusters, and first results on nearby galaxies. We discuss the synergy of integral field spectrographs at 8–10 m class telescopes with future facilities such as the extremely large telescope (ELT). [ABSTRACT FROM AUTHOR]

Due to its wide wavelength coverage, multi-resolution mode, and high transmission efficiency, the wide field multi-object spectrograph becomes the most common-used universal instrument in extremely large telescopes. It's still a great challenge to build the wide field multi-object spectrograph for a 30 m class telescope because of its sharply increased volume and budget. With the rapid development of astronomy and astrophysics, the innovation of astronomical technology is fundamentally required. In this paper, the research progress of different kinds of wide-field multi-object spectrographs is illustrated and reviewed, the recent status of conceptual designs and the instrument features of the wide field multi-object spectrographs of the three 30 m class telescopes in the world, especially the current effort made by the Chinese team for the wide field multi-object spectrograph of the Thirty Meter Telescope (TMT) are introduced. [ABSTRACT FROM AUTHOR]