Photometric System Research Articles

Mass Computations of the Brightness of Stars in an Arbitrary Spectral Band

The problem of calculating the brightness of an array of stars in an arbitrary photometric band, which is not the standard band of astronomical photometry, is considered from their multicolor photometry in some other photometric system. A similar problem is to transfer photometric measurements of stars from one multicolor photometric system to another. This task includes methods for calculating and comparing magnitudes, as well as merging photometric catalogs. The questions of choice of various zero-points of photometry and reduction of measurements for the atmosphere are considered. The issues of reducing the error of the proposed methods are discussed. The article is partly based on a report presented at the conference “Modern Stellar Astronomy-2022”, held at the Caucasian Mountain Observatory of the Sternberg State Astronomical Institute, Moscow State University, in November 8–10, 2022.

A measure of perceived quality to secure the polishability of new paint systems

The automotive industry continuously strives to reduce their environmental impact. For the paint shop it means to introduce more sustainable paint concepts, while maintaining the production rate and retain the right surface appearance that is crucial for the vehicle’s perceived quality. Today most painted parts are visually inspected and, if needed, manually repaired by abrasive polishing to eliminate spot defects. The repair process consists of one sanding step to remove the defect, and one or two rubbing/polishing steps to restore the surface, but still it tends to be a non-reliable process leaving patterns or clusters of shallow micro scratches seen as three-dimensional shapes moving over the surface when viewed from different angles like holograms. These so called ‘polishing roses’ are hard to detect in artificial light but clearly visible in Sunlight and therefore they constitute a constant quality issue. Accurate polishing procedures in combination with more objective inspection techniques would secure a high surface quality—but what is ‘accurate’? The overall scope of the study was to deepen the knowledge of paint systems to develop test routines for the polishability of coatings already during the development stage, and thereby ease the implementation of new coating systems in production. The study was based on collected process data from professional polishers to define a process window based on key parameters for successful end-of-line repairs of coated surfaces, i.e. strategies minimizing the occurrence of visible polishing traces. A CNC-machine was built up for the purpose to systematically test and evaluate new coating systems and repair procedures. The surface estimation was made by visual inspections as well as by a further developed photometric stereo system providing quantitative images of remaining repair traces.

Power-2 limb-darkening coefficients for the uvby, UBVRIJHK, SDSS ugriz, Gaia, Kepler, TESS, and CHEOPS photometric systems

Context. The phenomenon of limb-darkening is relevant to many topics in astrophysics, including the analysis of light curves of eclipsing binaries, optical interferometry, measurement of stellar diameters, line profiles of rotating stars, gravitational microlensing, and transits of extrasolar planets Aims. Multiple parametric limb-darkening laws have been presented, and there are many available sources of theoretical limb-darkening coefficients (LDCs) calculated using stellar model atmospheres. The power-2 limb-darkening law allows a very good representation of theoretically predicted intensity profiles, but few LDCs are available for this law from spherically symmetric model atmospheres. We therefore present such coefficients in this work. Methods. We computed LDCs for the space missions Gαiα, Kepler, TESS, and CHEOPS and for the passbands uυby, UBVRIJHK, and SDSS ugriz, using the PHOENIX-COND spherical models. We adopted two methods to characterise the truncation point, which sets the limb of the star: the first (M1) uses the point where the derivative dI(r)/dr is at its maximum – where I(r) is the specific intensity as a function of the normalised radius r – corresponding to µcri, and the second (M2) uses the midpoint between the point µcri and the point located at µcri–1. The LDCs were computed adopting the Levenberg–Marquardt least-squares minimisation method, with a resolution of 900 equally spaced µ points, and covering 823 model atmospheres for a solar metallicity, effective temperatures of 2300–12000 K, log g values from 0.0 to 6.0, and microturbulent velocities of 2 km s−1. As our previous calculations of LDCs using spherical models included only 100 µ points, we also updated the calculations for the four-parameter law for the passbands listed above, and compared them with those from the power-2 law. Results. Comparisons between the quality of the fits provided by the power-2 and four-parameter laws show that the latter presents a lower merit function, χ2, than the former for both cases (M1 and M2). This is important when choosing the best approach for a particular science goal.

A Catalog of Distance Determinations for the LAMOST DR8 K Giants in the Galactic Halo

We present a catalog of distances for 19,544 K giants drawn from Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) DR8. Most of them are located in the halo of the Milky Way up to ∼120 kpc. There are 15% K giants without Sloan Digital Sky Survey (SDSS) photometry, for which we supplements with Pan-STARRS1 (PS1) photometry calibrated to SDSS photometric system. The possible contamination of the red clumps/horizontal branch are removed according to metallicities and colors before the distance determination. Combining the LAMOST spectroscopic metallicities with the SDSS/PS1 photometry, we estimate the absolute magnitudes in the SDSS r band, the distance moduli, and the corresponding uncertainties through an Bayesian approach devised by Xue et al. for the Sloan Extension for Galactic understanding and exploration halo K giants. The typical distance precision is about 11%. The stars in the catalog lie in a region of 4–126 kpc from the Galactic center, of which with 6320 stars beyond 20 kpc and 273 stars beyond 50 kpc, forming the largest spectroscopic sample of distant tracers in the Milky Way halo so far.

M92 (NGC 6341) Is a Metal-complex Globular Cluster with an Atypical Primordial Population

We present a multiple stellar population study of the metal-poor globular cluster (GC) M92 (NGC 6341), which is long known for the substantial metallicity dispersion, using our own photometric system. We find two groups with slightly different mean metallicities, the metal-poor (MP) stars with [Fe/H] hk = −2.412 ± 0.03 and the metal-rich (MR) ones with −2.282 ± 0.002. The MP constitutes about 23% of the total mass with a more central concentration. Our populational tagging based on the [C/Fe] ch and [N/Fe] nh provides the mean n(P):n(I):n(E) = 32.2:31.6:36.2 (±2.4), where P, I, and E denote the primordial, intermediate, and extreme populations, respectively. Our populational number ratio is consistent with those of others. However, the MP has a significantly different populational number ratio than the mean value, and the domination of the primordial population in the MP is consistent with observations of Galactic GCs that less massive GCs contain larger fractions of the primordial population. Structural and constituent differences between the MP and MR may indicate that M92 is a merger remnant in a dwarf galaxy environment, consistent with recent suggestions that M92 is a GC in a dwarf galaxy or a remnant nucleus of the progenitor galaxy. Discrepancy between our method and those widely used for the Hubble Space Telescope photometry exists in the primordial population. Significant magnesium and oxygen depletions of −0.8 and −0.3 dex, respectively, and helium enhancement of ΔY ≳ 0.03 are required to explain the presence of this abnormal primordial group. No clear explanation is available with limited information of detailed elemental abundances.

Color Transformation Equations between Photometric Systems of the 2MASS Catalog and the ASTRONIRCAM Camera of the SAI MSU 2.5-m Telescope

Color Transformation Equations between Photometric Systems of the 2MASS Catalog and the ASTRONIRCAM Camera of the SAI MSU 2.5-m Telescope

In situ enzymatic generation of Au/Pt nanoparticles as an analytical photometric system: proof of concept determination of tyramine

In situ enzymatic generation of bimetallic nanoparticles, mainly Au/Pt, overcomes the drawbacks (continuous absorbance drift, modest LOQ, and long-time reaction) observed when AuNP alone are produced. In this study, Au/Pt nanoparticles have been characterized by EDS, XPS, and HRTEM images using the enzymatic determination of tyramine with tyramine oxidase (TAO) as a model. Under experimental conditions, the Au/Pt NPs show an absorption maximum at 580 nm which can be related to the concentration of tyramine in the range 1.0 × 10-6M to 2.5 × 10-4M with a RSD of 3.4% (n = 5, using 5 × 10-6M tyramine). The Au/Pt system enables low LOQ (1.0 × 10−6 M), high reduction of the absorbance drift, and a significant shortening of the reaction time (i.e., from 30 to 2 min for a [tyramine] = 1 × 10−4M); additionally, a better selectivity is also obtained. The method has been applied to tyramine determination in cured cheese and no significant differences were obtained compared to a reference method (HRP:TMB). The effect of Pt(II) seems to involve the previous reduction of Au(III) to Au(I) and NP generation from this oxidation state. Finally, a three-step (nucleation-growth-aggregation) kinetic model for the generation of NPs is proposed; this has enabled us to obtain a mathematical equation which explains the experimentally observed variation of the absorbance with time.Graphical abstract

Gamma Scientific Sets High Standards for Light Measurement

Gamma Scientific Sets High Standards for Light Measurement

HectoMAP: The Complete Redshift Survey (Data Release 2)

HectoMAP is a dense redshift survey of 95,403 galaxies based primarily on MMT spectroscopy with a median redshift z = 0.345. The survey covers 54.64 deg2 in a 1.°5 wide strip across the northern sky centered at a decl. of 43.°25. We report the redshift, the spectral indicator D n 4000, and the stellar mass. The red-selected survey is 81% complete for 55,962 galaxies with (g − r) > 1 and r < 20.5; it is 72% complete for 32,908 galaxies with (g − r) > 1, (r − i) > 0.5 and 20.5 < r < 21.3. Comparison of the survey basis SDSS photometry with the HSC-SSP photometry demonstrates that HectoMAP provides complete magnitude-limited surveys based on either photometric system. We update the comparison between the HSC-SSP photometric redshifts with HectoMAP spectroscopic redshifts; the comparison demonstrates that the HSC-SSP photometric redshifts have improved between the second and third data releases. HectoMAP is a foundation for examining the quiescent galaxy population (63% of the survey), clusters of galaxies, and the cosmic web. HectoMAP is completely covered by the HSC-SSP survey, thus enabling a variety of strong- and weak-lensing investigations.

Leukocyte Esterase Strip Quantitative Detection Based on RGB Photometry is a Probable Method to Diagnose Periprosthetic Joint Infection: An Exploratory Study.

Leucocyte esterase (LE) strip test is the most rapid, convenient, and cheap method to diagnose chronic periprosthesis joint infection (PJI). However, the determination of LE strip mainly relies on colorimetric method with strong subjectivity, which leads to low diagnostic accuracy. Therefore, we try to convert LE strip images into digital data through the RGB photometric system to achieve objective diagnosis. This method will greatly improve the accuracy of LE strip detection and diagnosis of PJI. From January 2021 to September 2021, 46 patients with suspected PJI after total hip and knee arthroplasty underwent diagnostic joint puncture. After effective joint fluid samples were harvested, they were divided into original fluid and centrifuged fluid for LE strip detection. Real-time images of LE strip were taken at 90 s, 3min, 5min, 10 min, and 15 min after sampling, and their brightness (Y) was obtained after they were input into an RGB photometric system. Grouping was based on centrifugation, infection, and time points, and then the differences in brightness among groups were compared. The correlation between LE strip image brightness and WBC count was evaluated. Student t-test was used for the parametric data and chi-square test for qualitative data. Simple linear regression was utilized to analyze the correlation between brightness and WBC count in each group. Included were 19 cases of PJI and 27 Non-PJI subjects diagnosed against ICM2018 diagnostic criteria. The brightness was lower in the PJI group than in Non-PJI group (p < 0.05). The brightness of the uncentrifuged group was lower than that of the centrifuged group (p< 0.05). Irrespective of centrifugation or infection, the brightness of LE strip decreased with the exposure time after sampling. The brightness of LE strip was correlated with WBC count at different time points, with the correlation being strongest 5min after sampling (R2 (5min)=0.86, p< 0.0001). The correlation between LE strip brightness and WBC count was also found in the centrifugation group, with the correlation being most robust 15 min after sampling (R2 (15 min)=0.73, p< 0.0001). A remarkable correlation was found between LE strip brightness and the WBC count. It is feasible to directly quantify LE strip image on a RGB photometer to achieve quantitative detection of LE strip to diagnose PJI.

NEOROCKS project: surface properties of small near-Earth asteroids

ABSTRACT We present new results of the observing program which is a part of the NEOROCKS project aimed to improve knowledge on physical properties of near-Earth Objects (NEOs) for planetary defense. Photometric observations were performed using the 1.2-m telescope at the Haute-Provence observatory (France) in the BVRI filters of the Johnson–Cousins photometric systems between June 2021 and April 2022. We obtained new surface colours for 42 NEOs. Based on the measured colours, we classified 20 objects as S-complex, nine as C-complex, nine as X-complex, two as D-type, one object as V-type, and one object remained unclassified. For all the observed objects, we estimated their absolute magnitudes and diameters. Combining these new observations with the previously acquired data within the NEOROCKS project extended our data set to 93 objects. The majority of objects in the data set with diameters D &amp;lt; 500 m belongs to a group of silicate bodies, which could be related to observational bias. Based on MOID and ΔV values we selected 14 objects that could be accessible by a spacecraft. Notably, we find D-type asteroid (163014) 2001 UA5 and A-type asteroid 2017 SE19 to be of particular interest as possible space mission targets.

SmaEPho–Smart Photometry in Education 4.0

Digitization offers new perspectives for educational research to identify the effects of visualizations regarding cognitive processing. In addition, new types of data can be generated, expanding the possibilities for visualizing cognitive processes and understanding human learning. Digital twins are already used in Industry 4.0, as an additional visualization to a real object, for data mining and data analysis for process optimization. The increasing integration of digital twins in the industrial sector requires the formulation of corresponding educational goals to ensure high-quality and future-oriented education. Therefore, future generations must be introduced to technologies from industry during their education. In this paper, an intelligent photometric measurement system called SmaEPho with a digital twin for science, technology, engineering, and mathematics (STEM) learning is presented. In addition to its function as a photometric measurement device, an intelligent sensor technology allows for data generation on the user’s usage behavior. The digital twin reflects and visualizes these data in real-time. This enables a variety of new didactic and methodological approaches in teaching. A first study evaluating the hardware and tracking components of SmaEPho shows that the deviation accuracy of the measurement system is sufficient for experimental applications in schools. Another study with n=52 students confirmed the excellent usability of the SmaEPho hardware platform. These research results lay the foundation for a variety of future research questions on data analysis and machine learning algorithms with the aim of increasing the quality of education. The use of intelligent digital twins as an element of digitization in educational contexts offers the extended possibility of identifying cognitive processing steps using this technology.

Interplay between lymphocyte subpopulation, inflammatory cytokines and their correlation with oxidative stress parameters in COVID-19

Our objective was to investigate the inflammatory and oxidative stress markers in patients with moderate and severe form of COVID-19. In addition, we show the correlation between changes in lymphocyte subsets and markers of oxidative stress as a tool for patient classification. IL-6 and VEGF were analysed by utilizing a High Sensitivity Evidence Investigator™ Biochip Array technology. The total antioxidant capacity (PAT) and the free radical concentrations (d-ROM) were measured in serum utilizing analytical photometric system FRAS5. Peripheral blood was used to determine CD45 + mononuclear, B, T, and NK cells using a multi-parameter flow cytometric immunophenotypic test.&#x0D; Statistically significant differences in IL-6 and VEGF levels were observed between the two patient groups. Decreased values of the absolute number of lymphocytes and their CD4 + and CD8 + positive T cells, NK cells, and CD8 were obtained. In the moderate group, good correlations were found between IL-6 and VEGF and NK cells (r = 0.6973, p &lt;0.05; for IL6 and r = 0.6498, p &lt;0, for VEGF. 05). Cytokines were correlated with CD45+ (r = 0.5610, p &lt;0.05; for IL-6 and r = 0.5462, p &lt;0.05 for VEGF). The oxidative stress index can be used as a cheaper alternative and as a triage tool between severe and moderate illnesses, after showing good correlation with more expensive patient classification analysis.

Solar photometric system for indirect measurement of the optical thickness for the surface layer of atmospheric aerosol

The possibility of using solar photometers for indirect measurement of the optical depth of surface aerosol is studied. The proposed method and the corresponding technique for indirect measurement of the optical depth of surface aerosol using solar photometers are theoretically substantiated. Two methods of indirect measurements are proposed. The first method makes it possible to determine the increase in the optical depth of surface aerosol with a single-channel solar photometer by performing two-stage indirect measurements. The second method allows to determine the increment of ground aerosol using a two-channel solar photometer with identical channels. An invariant that makes it possible to verify the accuracy of the obtained measurement data at proposed methods sharing is obtained. Keywords surface aerosol, photometer, optical depth, indirect measurements, surface layer of the troposphere

Simultaneous three-channel photometric system of 1.2 m photoelectric telescope

Simultaneous three-channel photometric system of 1.2 m photoelectric telescope

Very Metal-poor Stars in the Solar Vicinity: Age Determination

The ages of the oldest and most metal-poor stars in the Milky Way bear important information on the age of the universe and its standard model. We analyze a sample of 28 extremely metal-poor field stars in the solar vicinity culled from the literature and carefully determine their ages. To this aim, we critically make use of Gaia data to derive their distances and associated uncertainties. Particular attention has been paid to the estimate of the reddening and its effect on the derivation of stellar ages. We employed different reddenings and superimpose isochrones from different sources on the stars' color–magnitude diagram built up with different photometric systems. We highlight subtle metallicity effects when using the Johnson photometry for low-metallicity stars and finally adopt Gaia photometry. An automatic fitting method is devised to assign ages to each individual star taking into account the uncertainties in the input parameters. The mean age of the sample turns out to be 13.9 ± 0.5 Gyr using Padova isochrones, and 13.7 ± 0.4 Gyr using BASTI isochrones. We found also a group of very metal-poor stars ([Fe/H] = −2.7 to −2.0 dex) with relatively young ages, in the range 8–10 Gyr.

Machine Learning to Search for Accreting Neutron Star Binary Candidates Using Chinese Space Station Telescope Photometric System

Accreting neutron star binary (ANSB) systems can provide some important information about neutron stars (NSs), especially on the structure and the equation of state of NSs. However, only a few ANSBs are known so far. The upcoming Chinese Space Station Telescope (CSST) provides an opportunity to search for a large number of ANSB candidates. We aim to investigate whether or not a machine learning method may efficiently search for ANSBs based on CSST photometric system. In this paper, we generate some ANSBs and normal binaries under CSST photometric system by binary evolution and binary population synthesis method and use a machine learning method to train a classification model. We consider the classical multi-color disk and the irradiated accretion disk, then compare their effects on the classification results. We find that no matter whether the X-ray reprocessing effect is included or not, the machine learning classification accuracy is always very high, i.e., higher than 96%. If a significant magnitude difference exists between the accretion disk and the companion of an ANSB, machine learning may not distinguish it from some normal stars such as massive main sequence stars, white dwarf binaries, etc. False classifications of the ANSBs and the normal stars highly overlap in a color–color diagram. Our results indicate that machine learning would be a powerful way to search for potential ANSB candidates from the CSST survey.

Anomalous Cepheids: Updated Theoretical Period–Luminosity–Color and Period–Wesenheit Relations

AbstractIn the context of a project aimed to provide an updated theoretical scenario for various classes of radially pulsating stars, we present the first results obtained for anomalous Cepheids. By adopting reliable and updated evolutionary prescriptions concerning the luminosity levels for various core He-burning stellar models with masses suitable for entering the instability strip, we have computed nonlinear convective pulsation models for both fundamental and first-overtone mode anomalous Cepheids by exploring the impact of varying the metal abundance as well as the efficiency of super-adiabatic convection. These numerical simulations have allowed us to retrieve the boundaries of the instability strip and all relevant pulsation properties, namely period, amplitude, bolometric light and radial velocity curves. This theoretical scenario has been transformed into the Gaia photometric system to derive the first theoretical Period–Luminosity–Colour and Period–Wesenheit relations in the Gaia bands.

AlphaTg: GUI application for flux and limb derivatives of UBVRI, Kepler and TESS pass-bands for asteroseismology applications

The flux derivatives, limb darkening integrals and limb darkening derivatives have been used in many astronomical applications. Among these applications, the flux and limb darkening derivatives are mandatory parameters in asteroseismology whenever determining the theoretical amplitudes of stellar pulsations. The amplitude ratio method, which compares the observed amplitudes of UBVRI color bands with the theoretical amplitudes is widely used in asteroseismology. The computation of theoretical amplitudes is very complex and time-consuming due to the dependency on several parameters, including flux and limb darkening derivatives. Besides, more theoretical amplitude models are needed to compare with the observations for an ideal conclusion. In addition, the computation of synthetic line profiles in spectroscopy is also used the flux and limb darkening derivatives; therefore, we introduce the AlphaTg code to determine flux and limb darkening derivatives in a single application to minimize the complexity of computation. The facility enables to compute flux derivatives for any effective temperature (Teff) within the range of 3500 K ≤ Teff≤ 50000 K and any gravity value within the range of 0.0 ≤ log (g) ≤ 5.0 for UBVRI, Kepler and TESS photometric systems. The limb darkening derivatives can be determined for a spherical degree, l = 0, 1, and 2 for linear, quadratic and non-linear limb darkening laws for the effective temperature range of 3500 K ≤ Teff≤ 50000 K and gravity range of 1.0 ≤ log (g) ≤ 5.0. A case study is also discussed to explain the usage and limitations of the application.

A First Look at Cepheids in a Type Ia Supernova Host with JWST

We report the first look at extragalactic Cepheid variables with the James Webb Space Telescope (JWST), obtained from an archival observation of NGC 1365, host of SNIa 2012fr, a calibration path used to measure the Hubble constant. As expected, the high-resolution observations with NIRCam through F200W show better source separation from line-of-sight companions than Hubble Space Telescope (HST) images at similar near-infrared wavelengths, the spectral region that has been used to mitigate the impact of host dust on distance measurements. Using the standard star P330E as a zero-point and point-spread function reference, we photometered 31 previously known Cepheids in the JWST field, spanning including 24 Cepheids in the longer-period interval of . We compared the resultant period–luminosity (P-L) relations to that of 49 Cepheids in the full period range including 38 in the longer-period range observed with WFC3/IR on HST and transformed to the JWST photometric system (F200W, Vega). The P-L relations measured are in good agreement, with intercepts (at ) of 25.74 ± 0.04 and 25.72 ± 0.05 for HST and JWST, respectively. Our baseline result comes from the longer-period, higher signal-to-noise ratio Cepheids where we find 25.75 ± 0.05 and 25.75 ± 0.06 mag for HST and JWST, respectively. We find good consistency between this first JWST measurement and HST, and no evidence that HST Cepheid photometry is “biased bright” at the ∼0.2 mag level needed to mitigate the Hubble tension, though comparisons from more SN hosts are warranted and anticipated. We expect future optimized JWST observations to surpass these in quality.