Optical Observations Research Articles

The Concept of Electronic Pensioner in Some Countries Versus Romania

We aim to introduce the concept of e-pensioner (EP) with the intention of having this term used as a document within the European Union’s strategy on Artificial Intelligence (AI) for the period 2023-2027 and after implemented into the legislation of member countries. The relationship between older generations and emerging forms of digitalization and artificial intelligence is the focal point, aiming to provide an easily approachable dimension for pensioners. This article presents an analytical framework and approaches for integrating pensioners into the digital era. Following the exposition of theoretical foundations, the article delineates the use of pensioner cards in select countries worldwide. The intersection of pensioners with the digital era proves to be a fertile entry point for examining regulatory ordinances in the digital realm. A novel digital form, the AI-based digital portal, involves a technique of facial authentication for pensioners to send digital life certificates. Two key factors are named across all examined countries. The primary driver of digital transformation is propelled by the desire to enhance the efficiency and efficacy of public administration, which becomes particularly crucial as populations age, leading to increased demand for social services and competition for limited resources in the developed public sector. The innovative application of technology presents opportunities for streamlining processes, enhancing productivity, and reducing costs while concurrently improving service quality. The use of artificial intelligence (AI) in the management and administration of public pension funds stands for a natural progression of technology in the public domain. In an environment characterized by complexity and volatility, AI can provide a level of analysis and prediction that exceeds human ability. Presently, there exists a wide array of AI-powered tools for object detection, natural language processing, understanding and inference, optical character recognition, predictive analytics, anomaly detection, noise elimination, model forecasting, recommendation systems, and monitoring and observability.

The Recovery and Re-Calibration of a 13-Month Aerosol Extinction Profiles Dataset from Searchlight Observations from New Mexico, after the 1963 Agung Eruption

The recovery and re-calibration of a dataset of vertical aerosol extinction profiles of the 1963/64 stratospheric aerosol layer measured by a searchlight at 32°N in New Mexico, US, is reported. The recovered dataset consists of 105 aerosol extinction profiles at 550 nm that cover the period from December 1963 to December 1964. It is a unique record of the portion of the aerosol cloud from the March 1963 Agung volcanic eruption that was transported into the Northern Hemisphere subtropics. The data-recovery methodology involved re-digitizing the 105 original aerosol extinction profiles from individual Figures within a research report, followed by the re-calibration. It involves inverting the original equation used to compute the aerosol extinction profile to retrieve the corresponding normalized detector response profile. The re-calibration of the original aerosol extinction profiles used Rayleigh extinction profiles calculated from local soundings. Rayleigh and aerosol slant transmission corrections are applied using the MODTRAN code in transmission mode. Also, a best-estimate aerosol phase function was calculated from observations and applied to the entire column. The tropospheric aerosol phase function from an AERONET station in the vicinity of the searchlight location was applied between 2.76 to 11.7 km. The stratospheric phase function, applied for a 12.2 to 35.2 km altitude range, is calculated from particle-size distributions measured by a high-altitude aircraft in the vicinity of the searchlight in early 1964. The original error estimate was updated considering unaccounted errors. Both the re-calibrated aerosol extinction profiles and the re-calibrated stratospheric aerosol optical depth magnitudes showed higher magnitudes than the original aerosol extinction profiles and the original stratospheric aerosol optical depth, respectively. However, the magnitudes of the re-calibrated variables show a reasonable agreement with other contemporary observations. The re-calibrated stratospheric aerosol optical depth demonstrated its consistency with the tropics-to-pole decreasing trend, associated with the major volcanic eruption stratospheric aerosol pattern when compared to the time-coincident stratospheric aerosol optical depth lidar observations at Lexington at 42° N.

Optical observation and combustion properties during paper sludge fast heating

Optical observation and combustion properties during paper sludge fast heating

The Influence of Sudden Stratospheric Warming on the Development of Ionospheric Storms: The Alma-Ata Ground-Based Ionosonde Observations

This paper examines the response of the ionosphere to the impact of two moderate geomagnetic storms observed on January 17 and 26–27, 2013, under conditions of strong sudden stratospheric warming. The study uses data from ground-based ionosonde measurements at the Alma-Ata ionospheric station (43.25 N, 76.92 E) combined with optical observation data (The Spectral Airglow Temperature Imager (SATI)). Ionosonde data showed that the geomagnetic storms under consideration do not generate ionospheric storms but demonstrate some unusual types of diurnal foF2 variations with large (up to 60%) deviations in foF2 from median values observed during the night/morning periods on 13–15 and 20–23 January, which do not have any relation to solar or geomagnetic activity. Wave-like disturbances in foF2, h’F, and daily averaged foF2 values with a quasi-period of 5–8 days and peak-to-peak amplitude from about 1 MHz to 2 MHz (from 20% to 40%) and ~40 km are observed during the period 9–28 January, after registration of the occurrence of the major SSW event on 6–7 January. The observed variations in the OH emission rate are found to be quite similar to those observed in the ionospheric parameters that assume a community of processes in the stratosphere/mesosphere/ionosphere system. The study shows that the F region of the ionosphere is influenced by processes in the lower ionosphere, in this case by processes associated with sudden stratospheric warming SSW-2013, which led to modification of the structure of the ionosphere and compensation of processes associated with the development of the ionospheric storms.

Orbit Determination of Asteroid (469219) Kamo‘oalewa Using a Combination of Historical and New Observations

Abstract The orbit solution of near-Earth asteroids heavily relies on ground-based optical observations. The orbit uncertainty is limited by the insufficient observation quantity and quality. The Chinese Tianwen-2 mission targets a near earth asteroid (469219) Kamo‘oalewa and a main belt comet, 311P/PANSTARRS. To accurately determine the orbit of Kamo‘oalewa, more optical observations are needed. Autonomous observation experiments focusing on Kamo‘oalewa were carried out using the 2.16 m telescope at the Xinglong Observatory of the National Astronomical Observatory of China. We found that this telescope could observe near-Earth asteroids as faint as a magnitude of 22.8. Based on the stacking method and trailed star extraction algorithm, fourteen optical observations were obtained from 2022 to 2024. The orbit for Kamo‘oalewa was determined by combining our observations with historical observations between 2004 and 2024. The inclusion of our observations results in improved orbital uncertainties of Kamo‘oalewa by 18.67 km, 7.93 km, and 11.12 km (1σ) in the X, Y, and Z directions, respectively. Furthermore, by combining all existed and simulated observations, the uncertainty of the orbital determination of Kamo‘oalewa was analysed. When using an additional 180 group observations from three Chinese observatories over two years, the orbital uncertainties of Kamo‘oalewa in the three directions could be reduced to 30 km (1σ).

Possible X-ray cocoon emission from GRB 050709

Abstract The detection of the short gamma-ray burst (SGRB) 050709 by the HETE-2 satellite opened the door to understanding the nature of SGRBs, offering clues about their emission mechanism and progenitors, with the crucial aid of optical follow-up observations. Here, we revisit the prompt emission of GRB 050709. Our analysis reveals an initial hard spike ∼200 ms long, followed by a subsequent soft-tail emission lasting ∼300 ms. These components could be common among other SGRBs originating from binary neutron merger events, such as GW 170817 and GRB 170817A. Detailed temporal and spectral analyses indicate that the soft-tail emission might be attributed to the cocoon formed by the relativistic jet depositing energy into the surrounding material. We find the necessary cocoon parameters at the breakout, as consistent with numerical simulation results. We compared the physical parameters of this cocoon with those of other SGRBs. The relatively higher cocoon pressure and temperature in GRB 050709 may indicate a more on-axis jet compared with GRB 170817A and GRB 150101B.

Effect of annealing treatment of hot-rolled AZ31 magnesium alloy on properties and stress corrosion resistance of MAO coatings

PurposeThis study aims to study the formation mechanism of micro-arc oxidation (MAO) coating on AZ31 magnesium alloy and how the annealing process affects its corrosion resistance.Design/methodology/approachThis study involved immersion experiments, electrochemical experiments and slow strain rate tensile experiments, along with scanning electron microscopy, optical microscopy observation and X-ray diffraction analysis.FindingsThe findings suggest that annealing treatment can refine the grain size of AZ31 magnesium alloy to an average of 6.9 µm at 300°C. The change in grain size leads to a change in conductivity, which affects the performance of MAO coatings. The MAO coating obtained by annealing the substrate at 300°C has smaller pores and porosity, resulting in better adhesion and wear resistance.Originality/valueThe coating acts as a barrier to prevent corrosive substances from entering the substrate. However, the smaller pores and porosity reduce the channels for the corrosive solution to pass through the coating. When the coating cracks or falls off, the corrosive medium and substrate come into direct contact. Smaller and uniform grains have better corrosion resistance.

Modification of the Dielectric and Thermal Properties of Organic Frameworks Based on Nonterminal Epoxy Liquid Crystal with Silicon Dioxide and Titanium Dioxide.

A nonterminal liquid crystal epoxy monomer is used to create an epoxy-amine network with a typical diamine 4,4'diaminodiphenylmethane. The plain matrix is compared to matrices modified with inorganic fillers: TiO2 or SiO2. Conditions of the curing reaction and glass transition temperatures in the cured products are determined through differential scanning calorimetry and broadband dielectric spectroscopy. The curing process is also followed through optical and electrical observations. The dielectric response of all investigated networks reveals a segmental α-process related to structural reorientation (connected to the glass transition). In all products, a similar process associated with molecular motions of polar groups also appears. The matrix modified with TiO2 exhibits two secondary relaxation processes (β and γ). Similar processes were observed in the pure monomer. An advantage of the network with the TiO2 filler is a shorter time or lower temperature required for optimal curing conditions. The physical properties of cured matrices depend on the presence of a nematic phase in the monomer and nonterminal functional groups in the aliphatic chains. In effect, such cured matrices can have more flexibility and internal order than classical resins. Additional modifiers used in this work shift the glass transition above room temperature and influence the fragility index in both cases.

A Highly Optical Anisotropic Hybrid Perovskite for Efficient Manipulation of Light Polarization

AbstractOptical anisotropic (e.g., birefringent) crystals can manipulate the polarization of light and thus are widely applied in modern optical fields. Common birefringent crystals are almost exclusively limited to inorganic oxides with small birefringence. Here, a new 1D hybrid halide perovskite PZPbCl3 (PZ = phenazine) is reported, which consists of perfectly parallel Pb–Cl chains and PZ cations. Remarkably, polarized optical observations show that even a PZPbCl3 crystal with micrometer thickness can modulate the polarized light efficiently. Furthermore, PZPbCl3 exhibits exceptional birefringence up to 0.65@546 nm, which is significantly larger than that of commercial oxide crystals. According to first‐principles calculations and polarizability anisotropy analyses, it is found that this birefringence is mainly ascribed to the linear polymerization of π‐conjugated rings in PZ cations. Due to the rich physical properties and structural diversity of hybrid perovskites, it is believed that the introduction of excellent birefringence into the hybrid perovskites will bring unprecedented opportunities to the future explorations of polarization‐dependent functional materials.

Consequences of a low-mass, high-pressure, star formation mode in early galaxies

Abstract High resolution X-ray spectra reveal hidden cooling flows depositing cold gas at the centres of massive nearby early-type galaxies with little sign of normal star formation. Optical observations are revealing that a bottom-heavy Initial Mass Function is common within the inner kpc of similar galaxies. We revive the possibility that a low-mass star formation mode is operating due to the high thermal pressure in the cooling flow, thus explaining the accumulation of low-mass stars. We further explore whether such a mode operated in early, high-redshift galaxies and has sporadically continued to the present day. The idea links observed distant galaxies with black holes which are ultramassive for their stellar mass, nearby red nuggets and massive early-type galaxies. Nearby elliptical galaxies may be red but they are not dead.

Optical spectroscopic and photometric classification of the X-ray transient EP240309a (EP J115415.8−501810) as an intermediate polar

ABSTRACT We report on optical follow-up observations of an X-ray source initially detected by the Einstein Probe mission. Our investigations categorize the source as an intermediate polar, a class of magnetic cataclysmic variables, exhibiting an orbital period of 3.7614(4) h and a white dwarf spin period of 3.97 min. The orbital period was identified through TESS observations, while our high-speed photometric data, obtained using the 1.9m and Lesedi 1.0m telescopes at the South African Astronomical Observatory, revealed both the spin and beat periods. Additionally, we present orbitally phase-resolved spectroscopic observations using the 1.9m telescope, specifically centred on the H β emission line, which reveal two emission components that exhibit Doppler variations throughout the orbital cycle.

Multicolour photometry of LEO mega-constellations Starlink and OneWeb

ABSTRACT The development of low earth orbit (LEO) mega-constellation fundamentally threatens ground-based optical astronomical observations. To study the photometric properties of the LEO mega-constellations, we used the Xinglong 50 cm telescope to conduct a large-sample, high-precision, and multicolour target-tracking photometry of two typical LEO mega-constellations: Starlink and OneWeb. Over a three-month observation period starting on 2022 January 1, we collected 1447 light curves of 404 satellites in four typical versions: Starlink v1.0, DarkSat, VisorSat, Starlink v1.5, and OneWeb. According to data statistics, Starlink v1.0 has the smallest median magnitude at clear and Sloan Digital Sky Survey gri band, and OneWeb is the dimmest bus. The brightness of Starlink v1.5 is slightly brighter than VisorSat. We construct a detailed photometric model with solar phase angle variations by calculating the illumination-visibility geometry based on the orbital parameters. Our data analysis shows that the solar phase angle is the significant characteristic which influencing Starlink satellites’ brightness, but it is not sensitive to OneWeb satellites. VisorSat and Starlink v1.5 versions, which are equipped with deployable visors, have significantly reduced scattered light compared to the previous Starlink v1.0 version. The multiband LOWESS and colour index are analysed in characterizing the energy and colour features of LEO mega-constellation satellites. This work found that the proportion of scattered sunlight mitigation achieved with VisorSat and Starlink v1.5 was 55.1 and 40.4 per cent, respectively. The colour index of different buses shows an evident clustering feature. Our observation and analysis could provide valuable quantitative data and photometric models, which can contribute to assessing the impact of LEO mega-constellations on astronomical observations.

Project Hephaistos – II. Dyson sphere candidates from Gaia DR3, 2MASS, and WISE

ABSTRACT The search for extraterrestrial intelligence is currently being pursued using multiple techniques and in different wavelength bands. Dyson spheres, megastructures that could be constructed by advanced civilizations to harness the radiation energy of their host stars, represent a potential technosignature, that in principle may be hiding in public data already collected as part of large astronomical surveys. In this study, we present a comprehensive search for partial Dyson spheres by analysing optical and infrared observations from Gaia, 2MASS, and WISE. We develop a pipeline that employs multiple filters to identify potential candidates and reject interlopers in a sample of five million objects, which incorporates a convolutional neural network to help identify confusion in WISE data. Finally, the pipeline identifies seven candidates deserving of further analysis. All of these objects are M-dwarfs, for which astrophysical phenomena cannot easily account for the observed infrared excess emission.

Celestial Mechanics Leading up to the AAS Division on Dynamical Astronomy

This talk reviewed key developments leading to the establishment of the AAS Division on Dynamical Astronomy. In the 1890s, Simon Newcomb calculated astronomical constants and ephemerides for solar system bodies that were internationally adopted and used for 80 yr. The introduction of punch card equipment in the 1940s and computers in the 50s allowed much faster computations. Launches of Sputnik, Explorer, Vanguard, and Mercury satellites led to computing the orbits of satellites around the Earth and the field of astrodynamics. Dirk Brouwer's death in 1966 resulted in the celestial mechanics faculty at Yale spreading across the country. The space program, radar observations, and faster computers propelled advances in celestial mechanics. Teams at the Jet Propulsion Laboratory and Massachusetts Institute of Technology developed solar system ephemerides using numerical integrations fit to optical observations and radar ranging measurements. It was time for the AAS Division on Dynamical Astronomy.

Radar and Optical Observations and Physical Modeling of Binary Near-Earth Asteroid 2018 EB

We report radar, photometric, and visible-wavelength spectrophotometry observations of NEA 2018 EB obtained in 2018. The radar campaign started at Goldstone (8560 MHz, 3.5 cm) on April 7, and it was followed by more extensive observations from October 5 to 9 by both Arecibo (2380 MHz, 12.6 cm) and Goldstone. 2018 EB was observed optically on April 5, 8, and 9 and again on October 18. Spectrophotometry was obtained on October 19 with the SOAR telescope, and the data suggest that 2018 EB is an Xk-class object. The echo power spectra and delay-Doppler radar images revealed that 2018 EB is a binary system. Radar images constrained the satellite's diameter to 0.15−0.05+0.02 km, but the data were not sufficient for shape modeling. Shape modeling of lightcurves and radar data yielded an oblate primary with an effective diameter D = 0.30 ± 0.04 km and a sidereal rotation period of 4.3−0.5+0.6 hr. Measurements of delay-Doppler separations between the centers of mass of the primary and the satellite, along with the timing of a radar eclipse observed on October 9, resulted in an orbit fit for the satellite with a semimajor axis of 0.50−0.01+0.04 km, an eccentricity of 0.15 ± 0.04, a period of 16.85−0.26+0.33 hr, and an orbit pole constrained to the ecliptic longitudes and latitudes of λ=93−43°+27° and β=48−18°+7° . The system mass was estimated to be 2.03−0.08+0.52×1010 kg, which yielded a bulk density of 1.4−0.5+0.6 g cm−3. Our analysis suggests that 2018 EB has a low optical albedo of p V = 0.028 ± 0.016 and a relatively high radar albedo of η OC = 0.29 ± 0.11 at Arecibo and η = 0.22 ± 0.10 at Goldstone.

Mid-infrared Fine Structure Lines from the Galactic Warm Ionized Medium

The Warm Ionized Medium (WIM) hosts most of the ionized gas in the Galaxy and occupies perhaps a quarter of the volume of the Galactic disk. Decoding the spectrum of the Galactic diffuse ionizing field is of fundamental interest. This can be done via direct measurements of ionization fractions of various elements. Based on current physical models for the WIM we predicted that mid-IR fine structure lines of Ne, Ar and S would be within the grasp of the Mid-Infrared Imager-Medium Resolution Spectrometer (MIRI-MRS), an Integral Field Unit (IFU) spectrograph, aboard the James Webb Space Telescope (JWST). Motivated thus we analyzed a pair of commissioning data sets and detected [Ne ii] 12.81 μm, [S iii] 18.71 μm and possibly [S iv] 10.51 μm. The inferred emission measure for these detections is about 10 cm−6 pc, typical of the WIM. These detections are broadly consistent with expectations of physical models for the WIM. The current detections are limited by uncorrected fringing (and to a lesser extent by baseline variations). In due course, we expect, as with other IFUs, the calibration pipeline to deliver photon-noise-limited spectra. The detections reported here bode well for the study of the WIM. Along most lines-of-sight hour-long MIRI-MRS observations should detect line emission from the WIM. When combined with optical observations by modern IFUs with high spectral resolution on large ground-based telescopes, the ionization fraction and temperature of neon and sulfur can be robustly inferred. Separately, the ionization of helium in the WIM can be probed by NIRspec. Finally, joint JWST and optical IFU studies will open up a new cottage industry of studying the WIM on arcsecond scales.

Laser Irradiation of Carbonaceous Chondrite Simulants: Space-weathering Implications for C-complex Asteroids

Surfaces of carbonaceous asteroids (C-complex) have shown diverse, contrasting spectral variations, which may be related to space weathering. We performed laser irradiation experiments on CI and CM simulant material under vacuum to mimic the spectral alteration induced by micrometeorite impacts. We used in situ ultraviolet-visible and near-infrared reflectance spectroscopy to analyze spectral alterations in response to pulsed laser irradiation, as well as scanning electron microscopy and X-ray photoelectron spectroscopy to search for microstructural and compositional changes. Laser irradiation causes an increase in spectral slope (reddening) and a decrease in the albedo (darkening), and these changes are stronger in the ultraviolet-visible region. These spectral changes are likely driven by the excess iron found in the altered surface region although other factors, such as the observed structural changes, may also contribute. Additionally, while the 0.27 μm band appears relatively stable under laser irradiation, a broad feature at 0.6 μm rapidly disappears with laser irradiation, suggesting that space weathering may inhibit the detection of any feature in this spectral region, including the 0.7 μm band, which has typically been used an indicator of hydration. Comparing our laboratory results with optical spectrophotometry observations of C-complex asteroids, we find that the majority of objects are spectrally red and possess colors that are similar to our irradiated material rather than our fresh samples. Furthermore, we also find that “younger” and “older” C-complex families have similar colors, suggesting that the space-weathering process is near equal or faster than the time it takes to refresh the surfaces of these airless bodies.

Feedback and ionized gas outflows in four low-radio power AGN at z ∼ 0.15

An increasing number of observations and simulations suggests that low-power (< 1044 erg s−1) jets may be a significant channel of feedback produced by active galactic nuclei (AGN), but little is known about their actual effect on their host galaxies from the observational point of view. We targeted four luminous type 2 AGN hosting moderately powerful radio emission (∼1044 erg s−1), two of which and possibly a third are associated with jets, with optical integral field spectroscopy observations from the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT) to analyze the properties of their ionized gas as well as the properties and effects of ionized outflows. We combined these observations with Very Large Array (VLA) and e-MERLIN data to investigate the relations and interactions between the radio jets and host galaxies. We detected ionized outflows as traced by the fast bulk motion of the gas. The outflows extended over kiloparsec scales in the direction of the jet, when present. In the two sources with resolved radio jets, we detected a strong enhancement in the emission-line velocity dispersion (up to 1000 km s−1) perpendicular to the direction of the radio jets. We also found a correlation between the mass and the energetics of this high-velocity dispersion gas and the radio power, which supports the idea that the radio emission may cause the enhanced turbulence. This phenomenon, which is now being observed in an increasing number of objects, might represent an important channel for AGN feedback on galaxies

Nova 1670 (CK Vulpeculae) was a merger of a red giant with a helium white dwarf

Context. Nova 1670 is a historical transient bearing strong similarities to a recently recognized type of stellar eruption known as the red nova, which is thought to be powered by stellar mergers. The remnant of the transient, CK Vul, is observable today mainly through cool circumstellar gas and dust, and recombining plasma, but we have no direct view on the stellar object. Aims. Within the merger hypothesis, we aim to infer the most likely configuration of the progenitor system that resulted in Nova 1670. Methods. We collected the literature data on the physical properties of the outburst and the remnant (including their energetics), and on the chemical composition of the circumstellar material (including elemental and isotopic abundances). These data, which result from optical and submillimeter observations of the circumstellar gas of CK Vul, are summarized here. We performed simple simulations to analyze the form and the level of mixing within the material associated with the merger. We identified products of nuclear burning, among which we find ashes of hydrogen burning in the CNO cycles and in the MgAl chain, as well as signs of partial helium burning. Results. Based primarily on the luminosity and chemical composition of the remnant, we find that the progenitor primary had to be an evolutionarily advanced red giant branch star of a mass of 1–2 M⊙. The secondary was either a very similar giant, or –more likely– a helium white dwarf. While the eruption event was mainly powered by accretion, we estimate that about 12% of total energy is likely to have come from helium burning activated during the merger. The coalescence of a first-ascent giant with a helium white dwarf created a star with a rather unique internal structure and composition, which resemble those of early R-type carbon stars. Conclusions. Nova 1670 is the result of a merger between a helium white dwarf and a first-ascent red giant and is likely now evolving to become an early R-type carbon star.

Optical observations of the potentially hazardous asteroid (4660) Nereus at opposition 2021

On 11 December 2021 at 11 UTC, the near-Earth asteroid (4660) Nereus passed the Earth at a distance of 0.0263 au, reaching about 13th magnitude that made it an excellent target for ground-based observations. We observed the asteroid photometrically from 11 October 2021, when it was visible at V = 17.7 mag, until 16 February 2022 (at V = 18.0 mag), and spectroscopically on 10 December 2021 (V ∼ 13.1 mag).Lightcurve analysis of (4660) Nereus gave a rotational period of 15.184245±0.000015 h with amplitude of 0.796 ± 0.052 mag. Fitting the magnitude-phase curve with the standard HG, HG1G2, HG12 functions yielded the following values: HR = 18.68−0.13+0.07 mag, G = 0.30−0.11+0.05; HR = 18.64−0.84+0.42 mag, G1 = 0.21−0.11+0.05, G2 = 0.46−0.23+0.22; HR = 18.61−0.07+0.13 mag, G12 = 0.18−0.18+0.18. The color indices of the asteroid at phase angle of 72.9° were found to be as follows: (B−V) = 0.688 ± 0.084, (B−R) = 1.046 ± 0.073, (V−R) = 0.358 ± 0.047, (V−I) = 0.718 ± 0.050. Its equivalent diameter was estimated as 335−158+59 m. These values, as well as the computed values of G1 and G2 coefficients, indicate that (4660) Nereus belongs to E-class asteroids. The same conclusion was made based on the spectra obtained.