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Solar twins are stars of key importance to the field of astronomy and offer a multitude of science applications. Only a small number (≲200) of solar twins are known today, all of which are relatively close to our Sun (⁠|${\lesssim}{800}\, {\rm pc}$|⁠). The goal of our Survey for Distant Solar Twins (SDST) is to identify many more solar twin and solar analogue stars out to much larger distances (⁠|${\sim}{4}\, {\rm kpc}$|⁠). In this paper, we present a new method to identify solar twins using relatively low S/N, medium resolving power (⁠|$R\sim 28\, 000$|⁠) spectra that will be typical of such distant targets observed with HERMES on the |${3.9}\, {\rm m}$| Anglo-Australian Telescope (AAT). We developed a novel approach, namely epic , to measure stellar parameters (SPs) which we use to identify stars similar to our Sun. epic determines the stellar atmospheric parameters (effective temperature T eff, surface gravity log  g , and metallicity [Fe/H]) using differential equivalent width (EW) measurements of selected spectroscopic absorption features and a simple model, trained on previously analysed spectra, that connects these EWs to the SPs. The reference for the EW measurements is a high S/N solar spectrum which is used to minimize several systematic effects. epic is fast, optimized for Sun-like stars and yields SP measurements with small enough uncertainties to enable spectroscopic identification of solar twin and analogue stars up to |${\sim}{4}\, {\rm kpc}$| away using AAT/HERMES, i.e. |$\sigma \left(T_{\mathrm{eff}}, \log g, \textrm {[Fe/H]}\right) = \left({50}\, {\rm K}, {0.08}\, {\rm dex}, {0.03}\, {\rm dex}\right)$| on average at S/N = 25. [ABSTRACT FROM AUTHOR]

Studying light pollution is an interest to researchers in a wide range of fields including astronomy, biology, civil engineering, ecology, and social science. Consequently, numerous sky brightness metrics have been developed over the years. However, what metrics are truly representative of the night sky quality and unique to the measured feature? The US National Park Service Night Skies Program has collected more than 1500 sets of night skies data throughout the United States. For each data set, a maximum of 56 metrics were measured through the combination of the captured images, Sky Quality Meter readings, and visual observations. This paper analyses these measurements and identifies a distinctive set of night sky brightness metrics based on the principal component analysis. Three major findings emerge. First, the commonly used metrics, such as the zenith brightness, horizontal illuminance, maximum vertical illuminance, all-sky light pollution ratio, Bortle class, and limiting magnitude, are highly correlated. Secondly, the observed sky brightness often offers a good estimate of the artificial light level despite the natural varying night sky background. Thirdly, a set of six metrics that consists of the zenith brightness and sky brightness percentiles are more distinctive when used to concisely describe night sky characteristics. These findings suggest that long-term night sky monitoring can be efficiently carried out by measuring the sky brightness percentiles on the observed all-sky images. [ABSTRACT FROM AUTHOR]

Context. Precise continuum normalisation of merged échelle spectra is a demanding task that is necessary for various detailed spectroscopic analyses. Automatic methods have limited effectiveness due to the variety of features present in the spectra of stars. This complexity often leads to the necessity for manual normalisation which is highly time-consuming. Aims. The aim of this work is to develop a fully automated normalisation tool that works with order-merged spectra and offers flexible manual fine-tuning, if necessary. Methods. The core of the proposed method uses the novel, fully convolutional deep neural network (SUPP Network) that was trained to predict a pseudo-continuum. The post-processing step uses smoothing splines that give access to regressed knots, which are useful for optional manual corrections. The active learning technique was applied to deal with possible biases that may arise from training with synthetic spectra and to extend the applicability of the proposed method to features absent in this kind of spectra. Results. The developed normalisation method was tested with high-resolution spectra of stars with spectral types from O to G, and gives a root mean squared (RMS) error over the set of test stars equal to 0.0128 in the spectral range from 3900 Å to 7000 Å and 0.0081 in the range from 4200 Å to 7000 Å. Experiments with synthetic spectra give a RMS of the order of 0.0050. Conclusions. The proposed method leads to results that are comparable to careful manual normalisation. Additionally, this approach is general and can be used in other fields of astronomy where background modelling or trend removal is a part of data processing. [ABSTRACT FROM AUTHOR]

Counting pairs of galaxies or stars according to their distance is at the core of real-space correlation analyses performed in astrophysics and cosmology. Upcoming galaxy surveys (LSST , Euclid) will measure properties of billions of galaxies challenging our ability to perform such counting in a minute-scale time relevant for the usage of simulations. The problem is only limited by efficient access to the data, hence belongs to the big data category. We use the popular Apache Spark framework to address it and design an efficient high-throughput algorithm to deal with hundreds of millions to billions of input data. To optimize it, we revisit the question of non-hierarchical sphere pixelization based on cube symmetries and develop a new one dubbed the 'Similar Radius Sphere Pixelization' (SARSPix) with very close to square pixels. It provides the most adapted indexing over the sphere for all distance-related computations. Using LSST-like fast simulations, we compute autocorrelation functions on tomographic bins containing between a hundred million to one billion data points. In each case, we achieve the construction of a standard pair-distance histogram in about 2 min, using a simple algorithm that is shown to scale, over a moderate number of nodes (16–64). This illustrates the potential of this new techniques in the field of astronomy where data access is becoming the main bottleneck. They can be easily adapted to other use-cases as nearest-neighbours search, catalogue cross-match or cluster finding. The software is publicly available from https://github.com/astrolabsoftware/SparkCorr. [ABSTRACT FROM AUTHOR]

The Gaia early Data Release 3 has delivered exquisite astrometric data for 1.47 billion sources, which is revolutionizing many fields in astronomy. For a small fraction of these sources, the astrometric solutions are poor, and the reported values and uncertainties may not apply. Before any analysis, it is important to recognize and excise these spurious results – this is commonly done by means of quality flags in the Gaia catalogue. Here, we devise a means of separating 'good' from 'bad' astrometric solutions that is an order of magnitude cleaner than any single flag: 99.3 per cent pure and 97.3 per cent complete, as validated on our test data. We devise an extensive sample of manifestly bad astrometric solutions, with parallax that is negative at ≥4.5σ; and a corresponding sample of presumably good solutions, including sources in healpix pixels on the sky that do not contain such negative parallaxes, and sources that fall on the main sequence in a colour–absolute magnitude diagram. We then train a neural network that uses 17 pertinent Gaia catalogue entries and information about nearby sources to discriminate between these two samples, captured in a single 'astrometric fidelity' parameter. A diverse set of verification tests shows that our approach works very cleanly, including for sources with positive parallaxes. The main limitations of our approach are in the very low signal-to-noise ratio and the crowded regime. Our astrometric fidelities for all of eDR3 can be queried via the Virtual Observatory, our code and data are public. [ABSTRACT FROM AUTHOR]

Superclusters are the largest objects in the Universe, and they provide a unique opportunity to study how galaxy clusters are born at the junction of the cosmic web as well as the distribution of magnetic fields and relativistic particles beyond cluster volume. The field of radio astronomy is going through an exciting and important era of the Square Kilometer Array (SKA). We now have the most sensitive functional radio telescopes, such as the MeerKAT, which offers high angular resolution and sensitivity towards diffuse and faint radio sources. To study the radio environments around supercluster, we observed the (core part of) Saraswati supercluster with the MeerKAT. From our MeerKAT Observation of the Saraswati Supercluster (MOSS) project, the initial results of the pilot observations of two massive galaxy clusters, A2631 and ZwCl2341.1+0000, which are located around the dense central part of the Saraswati supercluster, were discussed. In this paper, we describe the observations and data analysis details, including direction-dependent calibration. In particular, we focus on the ZwCl2341.1+0000 galaxy cluster, which hosts double radio relics and puzzling diffuse radio source in the filamentary network. We have imaged these double radio relics in our high resolution and sensitive L -band MeerKAT observation and a puzzling radio source, located between relics, in the low-resolution image. We also derived the spectra of double radio relics using MeerKAT and archival GMRT observations. The following papers will focus on the formation of radio relics and halo, as well as radio galaxy properties in a supercluster core environment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Al-Qadisiya In Arts & Educational Science is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Physics is not a very popular subject at German schools, and several studies indicate that girls are less interested than boys in the traditional physics curriculum. To address this problem, physics education should be up to date, context oriented, interesting for girls and boys, and emerge from their everyday life. The ROSE study shows that astronomy, human biology, and space are interesting for boys and girls and therefore a suitable context for physics lessons. In the field of astronomy and space exploration, the research is both highly current and part of the students' life, as they hear about discoveries and missions in the news. One possible future space mission is the human exploration of Mars. Such a trip is not easy; various factors have to be considered and risks must be minimized. One risk is the vacuum in space while there is higher air pressure in the spaceship itself. This aspect must be taken into account when designing a spaceship, for example, the "Crew Dragon" by Space X. [ABSTRACT FROM AUTHOR]

Molecular astronomy is a field that is blooming in the era of large observatories such as the Atacama Large Millimeter/Submillimeter Array (ALMA). With modern, sensitive, and high spectral resolution radio telescopes like ALMA and the Square Kilometer Array, the size of the data cubes is rapidly escalating, generating a need for powerful automatic analysis tools. This work introduces MolPred, a pilot study to perform predictions of molecular parameters such as excitation temperature (Tex) and column density (log(N)) from input spectra by the use of neural networks. We used as test cases the spectra of CO, HCO+, SiO and CH3CN between 80 and 400 GHz. Training spectra were generated with MADCUBA, a state-of-the-art spectral analysis tool. Our algorithm was designed to allow the generation of predictions for multiple molecules in parallel. Using neural networks, we can predict the column density and excitation temperature of these molecules with a mean absolute error of 8.5% for CO, 4.1% for HCO+, 1.5% for SiO and 1.6% for CH3CN. The prediction accuracy depends on the noise level, line saturation, and number of transitions. We performed predictions upon real ALMA data. The values predicted by our neural network for this real data differ by 13% from the MADCUBA values on average. Current limitations of our tool include not considering linewidth, source size, multiple velocity components, and line blending. [ABSTRACT FROM AUTHOR]

For the AstroSat 5-Year Special Issue, we present a tutorial on the usage of the CCDLAB Pipeline for UVIT data reduction from Level 1 raw data to completed science images. The tutorial informs us of the unique data-processing requirements for reducing UVIT data, including one unique development borne out of such reduction applicable to the field of astronomy in general in the form of a novel approach to solving world coordinate solutions. [ABSTRACT FROM AUTHOR]

In this study, a bibliometric evaluation of the articles published between 1975 and 2020 in astronomy education in the Web of Science database is aimed to reveal the trend in this field and to compare the articles from Turkey with other countries. During the article search process, the keyword "astronomy" was scanned both in the title and content of the articles. A total of 284 articles were reviewed under the Education/Educational Research category. VOSviewer (V1.6.15) package program was used to create and visualize bibliometric network maps of the articles examined within the scope of the study. In the findings, it was seen that approximately four-fifths of the articles published in the field of astronomy education have been published in the last ten years. It was determined that the most effective country in which publications are made on astronomy education is the USA, and Turkey is in the second place with 25 articles. It is noteworthy that while the average number of citations per publication for all the articles examined is 14.62, the average number of citations for articles originating from Turkey is 3.56. Based on such findings, Turkey's academic publication performance in astronomy education has been tried to be revealed. [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]

The field of gravitational-wave astronomy has been opened up by gravitational-wave observations made with interferometric detectors. This review surveys the current state-of-the-art in gravitational-wave detectors and data analysis methods currently used by the Laser Interferometer Gravitational-Wave Observatory in the United States and the Virgo Observatory in Italy. These analysis methods will also be used in the recently completed KAGRA Observatory in Japan. Data analysis algorithms are developed to target one of four classes of gravitational waves. Short duration, transient sources include compact binary coalescences, and burst sources originating from poorly modeled or unanticipated sources. Long duration sources include sources which emit continuous signals of consistent frequency, and many unresolved sources forming a stochastic background. A description of potential sources and the search for gravitational waves from each of these classes are detailed. [ABSTRACT FROM AUTHOR]

In the paper, the important role of tools and distributed IT resources in the dynamic development of astrophysics, astronomy, and space exploration are discussed. New possibilities and approaches to conducting research in the field of astronomy and astrophysics with the use of cloud computing and advanced data visualization techniques are also presented. Finally, some examples of the use of digital sky survey databases in scientific research are shown. [ABSTRACT FROM AUTHOR]

Nested sampling is an important tool for conducting Bayesian analysis in Astronomy and other fields, both for sampling complicated posterior distributions for parameter inference, and for computing marginal likelihoods for model comparison. One technical obstacle to using nested sampling in practice is the requirement (for most common implementations) that prior distributions be provided in the form of transformations from the unit hyper-cube to the target prior density. For many applications – particularly when using the posterior from one experiment as the prior for another – such a transformation is not readily available. In this letter, we show that parametric bijectors trained on samples from a desired prior density provide a general purpose method for constructing transformations from the uniform base density to a target prior, enabling the practical use of nested sampling under arbitrary priors. We demonstrate the use of trained bijectors in conjunction with nested sampling on a number of examples from cosmology. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Surra Man Ra'a is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Geodetic very long baseline interferometry (VLBI) observations are carried out, with the legacy system, using two well‐separated frequency bands in order to determine first‐order ionospheric delay corrections corresponding to the combined effect of total electron content (TEC) at two stations forming a baseline. On the other hand, it is possible to obtain the vertical TEC (VTEC) above the VLBI antennas from VLBI data. This research intends to investigate the role of the ionospheric spatial gradient on VTEC which is derived from VLBI observations based on the latest four Continuous VLBI Campaigns (CONT08 to CONT17‐L1). For this purpose, station‐based VTEC values were computed in two modes, with and without spatial gradients. Then, these two approaches were evaluated by comparison to global ionospheric maps (GIMs). The differences between the GIM‐based VTEC values and the VLBI VTEC values derived using two parameterization approaches were used to compute the Root Mean Square Error (RMSE) for each VLBI station during the CONTs. In addition, the improvement percentages of the VLBI VTEC's error were calculated to understand the spatial gradient role. Based on the obtained results, the role of spatial gradient is more significant on the equatorial region as compared to the polar area. Using the ionospheric spatial gradient decreases the RMSE values of VLBI‐derived VTEC values from CONT08, CONT11, CONT14, and CONT17‐L1 by 26.4%, 37.6%, 32.4%, and 27.4%, respectively. In addition, it is also shown that this parameter reduces the RMSE values during the high solar activity, as in 2011 and 2014. Plain Language Summary: In this study, we tried to use a special tool to estimate part of the atmosphere. To use the data of this technique, we used two common models. Here we examined them and identified the effect of the component in which they differ. The results showed that different geographical locations and years of study of this quantity are very effective. Key Points: The role of spatial gradient is more significant on the equatorial region as compared to other areasSpatial gradients improve accuracy of the VTEC (vertical total electron content) estimates from very long baseline interferometry (VLBI) observation, especially in periods when the solar activity is highThe role of the spatial gradient in estimating VLBI VTEC is related to the latitude of the VLBI station [ABSTRACT FROM AUTHOR]

Starting in the late 19th century, the Harvard Observatory hired women to study stars via the Astronomical Photographic Glass Plate Collection. Some of these women—such as Annie Jump Cannon, Henrietta Leavitt, and Cecilia Payne-Gaposchkin—made discoveries that changed astrophysics forever. However, they were far from the only women working at the Harvard Observatory during the era of astronomical glass plate photography. Historically, most of these women have been anonymous. The names found on over 400,000 glass plate envelopes were compiled into a list of all the women who left their mark on the collection between 1875 and 1975. Through this list of names, it is revealed that Harvard's glass plate collection acted as a haven for women who wanted to study the stars, long before they found equality in the field of astronomy. [ABSTRACT FROM AUTHOR]

In this contribution, we seek to identify points of contact between the conceptions about space, time, and Cosmos, carried out by thinkers and scientists throughout history, and the corresponding cosmogonic view of the Inka culture. We conclude that a proper understanding and interpretation of the Inka legacy in the fields of astronomy and archeoastronomy can only be carried out properly when inserted in the context of the Inka culture and its worldview. [ABSTRACT FROM AUTHOR]

Confidence in astrology remains a visible phenomenon in contemporary society, and this is a constant topic of academic interest. A survey based on 512 valid questionnaires were obtained from a non-probability sample of university students from Bucharest, in order to observe possible statistical relations between confidence in astrology, confidence in sciences such as medicine and mathematics, but also fields such as astronomy and horoscope. On the other hand, several statements have been used to measure the level of religiosity. Notable is the moderate positive correlation obtained between astrology and astronomy, but also the strong correlation between astrology and horoscope (this last correlation was expected). Broadly speaking, it is observed that astrology correlates positively with the variables that constitute the ‘inward’ component of religiosity, while the ‘outward’ component shows a rather negative correlation, but which does not enjoy a similar statistical significance. Astronomy, like medicine, outlines negative relation with the level of religiosity. Instead, the correlations that involve trust in medicine have a negative and moderate value, in relation to religiosity. In conclusion, it is observed that the trust in “strong sciences” generates more prompt correlations compared to the trust in astrology, while further studies are needed to clarify the reasons for such uncertain correlations between astrology and religiosity. [ABSTRACT FROM AUTHOR]

As the field of space-based astronomy opened up in the 1970s, Canadian astronomers began to think about how they could use these new tools to advance their research. While discussions were stimulated when work began on the Hubble Space Telescope, a proposal was made in the late 1970s to orbit an ultraviolet survey telescope, the Canadian Space Telescope. The CST was put aside starting in 1980 in favour of a proposal for Canadians to join U.S. and Australian astronomers in placing a similar instrument along with a spectrograph on board Starlab, which would fly in the Space Shuttle payload bay and later on a space platform that would be deployed and retrieved by the Shuttle. The Starlab project came to an end in 1984 without ever leaving the drawing board when Canada withdrew. This paper examines Canada's early work in space astronomy and the problems all three partners in Starlab faced in their attempt to bring the concept to fruition. [ABSTRACT FROM AUTHOR]

Pulsars are highly magnetized, rotating neutron stars with small volume and high density. The discovery of pulsars is of great significance in the fields of physics and astronomy. With the development of artificial intelligent, image recognition models based on deep learning are increasingly utilized for pulsar candidate identification. However, pulsar candidate datasets are characterized by unbalance and lack of positive samples, which has contributed the traditional methods to fall into poor performance and model bias. To this end, a general image recognition model based on adversarial training is proposed. A generator, a classifier, and two discriminators are included in the model. Theoretical analysis demonstrates that the model has a unique optimal solution, and the classifier happens to be the inference network of the generator. Therefore, the samples produced by the generator significantly augment the diversity of training data. When the model reaches equilibrium, it can not only predict labels for unseen data, but also generate controllable samples. In experiments, we split part of data from MNIST for training. The results reveal that the model not only behaves better classification performance than CNN, but also has better controllability than CGAN and ACGAN. Then, the model is applied to pulsar candidate dataset HTRU and FAST. The results exhibit that, compared with CNN model, the F-score has increased by 1.99% and 3.67%, and the Recall has also increased by 6.28% and 8.59% respectively. [ABSTRACT FROM AUTHOR]

Copyright of Al-Adab / Al-ādāb is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article highlights the participation of the Ukrainian scientist, Professor Vitaly Mikhailovich Grigorevsky, doctor of physical and mathematical sciences, and representative of the scientific school of Vladimir Platonovich Tsesevich, in the organization and development of international cooperative partnership in the field of satellite astronomy and photometric studies of artificial satellites of the Earth. The activity of the scientist in the coordination of scientific research of the countries of Eastern Europe in 1965- 1973 under the SPIN program, carried out under the auspices of the Astronomical Council of the USSR Academy of Sciences, is discussed. The article explores the main forms of Grigorevsky's scientific cooperation with the world's leading experts in the field of satellite astronomy--the British scientist Desmond King-Hele, the Czech astronomer František Link, Hungarian researchers Iván Almár and D. Toth, and others. Also, the achievements of the Latvian researchers Māris Ābele and Kasimirs Lapushka in the creation of photographic cameras of surveillance of satellites are analysed. [ABSTRACT FROM AUTHOR]

The formation and evolution of binary stars are critical components of several fields in astronomy. The most numerous sources for gravitational wave observatories are inspiraling or merging compact binaries, while binary stars are present in nearly every electromagnetic survey regardless of the target population. Simulations of large binary populations serve to both predict and inform observations of electromagnetic and gravitational wave sources. Binary population synthesis is a tool that balances physical modeling with simulation speed to produce large binary populations on timescales of days. We present a community-developed binary population synthesis suite, COSMIC, which is designed to simulate compact-object binary populations and their progenitors. As a proof of concept, we simulate the Galactic population of compact binaries and their gravitational wave signals observable by the Laser Interferometer Space Antenna. [ABSTRACT FROM AUTHOR]

Carl Friedrich Gauss (1777–1855) was one of the most eminent scientists of all time. He was born in Brunswick, studied in Göttingen, passed his doctoral examination in Helmstedt, and from 1807 until his death, was the director of the Göttingen Astronomical Observatory. As a professor of astronomy, he worked in the fields of astronomy, mathematics, geodesy, and physics, where he made world-famous and lasting contributions. In his honour, and to preserve his memory, the Gauss Society was founded in Göttingen in 1962. The present paper aims to give nonspecialists a brief introduction into the life of Gauss and an introduction into the Gauss Society and its history. [ABSTRACT FROM AUTHOR]

The joint detection of gravitational wave (GW) and electromagnetic radiation from the binary neutron star merger event GW170817 marks a breakthrough in the field of multi-messenger astronomy. The short gamma-ray burst (sGRB) GRB 170817A, associated with this binary neutron star merger event, has an isotropic-equivalent gamma-ray radiation luminosity of 1.6 × 1047 erg s−1, which is much lower than that of other sGRBs. The measurement of the superluminal movement of the radio afterglow emission confirms the presence of the relativistic jet, and the emission features can be well explained by the structured jet model. In this paper, we calculate the luminosity distribution of sGRBs and its evolution with redshift based on the structured (Gaussian) jet model, and find that the typical luminosity increase with redshift, for nearby sGRBs (such as for luminosity distance less than 200 Mpc) the typical gamma-ray luminosity is just around 1047–1048 erg s−1, which naturally explains the very low radiation luminosity of GRB 170817A. We derived the detection probability of sGRBs by Fermi-GBM and found that the expected detection rate of sGRBs is only about 1 yr−1 within the distance of several hundred Mpc. We explored the effect of the power-law index α of the merger time distribution on the observed characteristics and found that it had little effect on the observed luminosity and viewing-angle distributions. However, it is very interesting that, for different values of α, the distributions of the number of observed sGRBs are quite different, so it is possible to determine the value of α through observed distributions of the number of sGRBs. We used the Bayesian method to make a quantitative analysis and found that the value of α may be identified when the number of observed sGRBs with known redshifts is more than 200. Finally, we compare our results of gamma-ray luminosity distribution with sGRBs with known redshifts, and found that our results are consistent with the observation, which implies that our simulation results can reproduce the observed luminosity distribution well. [ABSTRACT FROM AUTHOR]

The GW170817 event opened a new window to test modifications to General Relativity with the aim of discard or impose strong constraints in extra dimension theories of gravity. Concerning these theories, the Randall–Sundrum brane-world theory – 4+1 spacetime model where its covariant Einstein field equations are composed with new extra terms that comes from extra dimensions – is begin tested in the multi-messenger astronomy field. In the same context, the aim of this paper is to impose new constrictions through measurements of the time-delay between the gravitational and electromagnetic signals: GW170817 and the recent S190425z, over the free cosmological parameters of this modified model. We assume that Gravitational Waves travel along a shortcut on the extra dimension. In addition, we consider the standard Λ CDM model and perform a likelihood analysis in order to study effects like the H 0 tension in comparison to this extra-dimensional theory, obtaining a reduced H 0 value of the order of 0.2 % in the low energy limit of this theory. [ABSTRACT FROM AUTHOR]

The article is devoted to the creative achievements of scientists of the second half of the nineteenth – beginning of the twentieth centuries, whose research contributed to the formation of new scientific thought. In the intellectual space of the time, scientific societies were one of the effective forms of organization of domestic research. In particular, in 1889 the Kyiv Physical and Mathematical Society was founded. According to the charter, the society was required not only to carry out research work in mathematics and physics, but also to teach and promote scientific knowledge. At the meetings of the Society, such prominent scientists as: in the field of mechanics – H. K. Suslov, P. V. Voronets, M. Ye. Zhukovskyi, I. I. Rakhmaninov, in the field of mathematics - Ye. P. Yermakov, B. Ya. Bukreiev, H. V. Pfeiffer, D. O. Hrave, M. Ye. Vashchenko-Zakharchenko, in the field of physics - M. P. Avenarius, M. M. Shyller, K. M. Zhuk, Y. Y. Kosonohov, H. H. De-Metts, in the field of astronomy – M. F. Khandrikov and others. The topics of the reports were quite diverse and covered all major fields of science, usually containing original material. Then it was processed in the form of articles, and sometimes monographs and published in well-known Russian and foreign mathematical journals, in the news of the Kyiv University or in the protocols of the society. Thus, many new theorems and original thoughts and solutions were first announced at the meetings of the society, and subsequently spread in the scientific society. Research topics were determined mainly by the interests of scientists and sometimes by regional needs. Only since 1914, in connection with the needs of the war, researchers began to engage in radiography, vacuum machinery, optics etc. However, these trends started actively develop after 1917. [ABSTRACT FROM AUTHOR]

The lunar crescent visibility criterion study is one of the most nontrivial discussions in the field of astronomy. A lunar crescent visibility criterion is used for calendrical determination, and a different lunar crescent visibility criterion results in different dates of calendar. This paper endeavors to provide an assessment for modern lunar crescent visibility criterion using swarm plot analysis, contradiction rate analysis, and regression analysis, based on 8290 collected data of lunar crescent sighting. The result analysis provides new comparative insight on modern lunar crescent visibility criterion, and suggest a new criterion based on the data of lunar crescent sighting. • This study compares lunar crescent visibility criteria, revealing limitations, successes, and proposing alternatives for discussion based on 8290 data. [ABSTRACT FROM AUTHOR]

A millenary description of the world as conceived by Chinese culture, appears in the Zhou bi Suanjing or "The book of the Gnomon and the Circular Paths of the Heaven", according Needham. Situated at Zhou (a legendary city) the dimensions of the earth and heaven, including the size of the Sun are presented in this book. The Chinese Gaì Ti'an astronomical model of a flat earth and a flat heaven, is measured with the aid of a gnomon (biao) and the application of the Pythagorean Theorem. Now, after making an adjustment to the scale of the data, the elements to locate the legendary Zhou City have been found making feasible the correspondence between the dimensions of the Zhoubi's given world and those of the actual Earth. Here I show that Zhou, centre of the world from which the measures are done, corresponds to the city Jining located in the province of Shandong, China; also, I confirm that the distance between Jining and the Pole of Zhoubi is 4,285 km as could be found with a geographical tool such as the Google-Earth program. With these results I am confident to say that: The city of Zhou appearing in the Zhoubi exists; and, that the Zhoubi was an accurate description of the Earth at the time of Zhou Dynasty (1045 - 256 BC). Moreover, the location of cities as important as Beijing (at 498 km to the north of Jining) would be related with projection of the heaven on Earth: it is about one diameter of Sun from Jining. Also, it important to know that this city is recognized as the birth place of the great philosopher Confucius, giving to my findings a relevance that goes beyond the field of Astronomy or Mathematics, in which frame the Zhoubi has been analysed through the years. These findings put new perspectives for the search in other non-mathematical or non-astronomical documents elements for these disciplines. [ABSTRACT FROM AUTHOR]

Copyright of Al-Mustansiriya Journal of Arts is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The measurement of ultra-high energy (UHE) neutrinos (E > 1016 eV) opens a new field of astronomy with the potential to reveal the sources of ultra-high energy cosmic rays especially if combined with observations in the electromagnetic spectrum and gravitational waves. The ARIANNA pilot detector explores the detection of UHE neutrinos with a surface array of independent radio detector stations in Antarctica which allows for a cost-effective instrumentation of large volumes. Twelve stations are currently operating successfully at the Moore's Bay site (Ross Ice Shelf) in Antarctica and at the South Pole. We will review the current state of ARIANNA and its main results. We report on a newly developed wind generator that successfully operates in the harsh Antarctic conditions and powers the station for a substantial time during the dark winter months. The robust ARIANNA surface architecture, combined with environmentally friendly solar and wind power generators, can be installed at any deep ice location on the planet and operated autonomously. We report on the detector capabilities to determine the neutrino direction by reconstructing the signal arrival direction of a 800 m deep calibration pulser, and the reconstruction of the signal polarization using the more abundant cosmic-ray air showers. Finally, we describe a large-scale design – ARIA – that capitalizes on the successful experience of the ARIANNA operation and is designed sensitive enough to discover the first UHE neutrino. [ABSTRACT FROM AUTHOR]

In the last years, Astroinformatics has become a well-defined paradigm for many fields of Astronomy. In this work, we demonstrate the potential of a multidisciplinary approach to identify globular clusters (GCs) in the Fornax cluster of galaxies taking advantage of multiband photometry produced by the VLT Survey Telescope using automatic self-adaptive methodologies. The data analysed in this work consist of deep, multiband, partially overlapping images centred on the core of the Fornax cluster. In this work, we use a Neural Gas model, a pure clustering machine learning methodology, to approach the GC detection, while a novel feature selection method (ΦLAB) is exploited to perform the parameter space analysis and optimization. We demonstrate that the use of an Astroinformatics-based methodology is able to provide GC samples that are comparable, in terms of purity and completeness with those obtained using single-band HST data and two approaches based, respectively, on a morpho-photometric and a Principal Component Analysis using the same data discussed in this work. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Social Sciences Institute / Sosyal Bilimler Enstitüsü Dergisi is the property of Bingol University / Rectorate and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The field of astronomy dealing with comets is an important component of modern space investigations. This applies both to the study of physical, chemical, and evolutionary parameters and to the determination of connections between meteor showers and their parental bodies. This paper considers the isodensity analysis of Arend‐Roland, 45P/Honda, and Bennett comets using the measurements of photographic plates performed at Engelhardt Astronomical Observatory. On the basis of a software aimed at analyzing the brightness of digital images, structural models for three comets were developed. The isophotes of their nuclei, comas, and tails were determined as well. As the cometary nuclei are the elements of dynamical evolution and processes in the Solar Nebula, the study of a digital database on comets will allow refining the theory of their formation and evolution. [ABSTRACT FROM AUTHOR]

The concept of the OOS of spacecraft can be traced back to the 1960s, when the main focus was on providing the necessary maintenance to advance the lifetime of spacecraft and extending the scale and function through on-orbit assembly. During the past decades, the Hubble Space Telescope has made great contributions to the fields of astronomy and physics through both observational data and the success of five OOS missions to overcome big challenges. That included an initial flaw of its primary mirror and subsequent obstacles associated with replacing and upgrading its science instruments. Furthermore, many programs have been carried out in the area of the OOS of spacecraft with successful operations in space. It could be exemplified by the assembly of the International Space Station, service verification of ETS-VII and Orbital Express, and detailed research for future applications including servicer and client satellites and particularly large space systems. This paper attempts to summarize all reported programs of the OOS in terms of engineering developments and provide an overall perspective for investigators in this field. Based on the reviewed programs, an analysis is carried out to elucidate the logical architectures of the mission and technology of the OOS of spacecraft. Further attention is paid to discussions of the enabling technologies that support the development of the OOS and related spacecraft. As an outlook, the future development and challenges of the OOS and the application of novel technologies are finally discussed to extend the present review work. [ABSTRACT FROM AUTHOR]

Copyright of HUM: Journal of the Faculty of Arts at the University of Mostar is the property of University of Mostar, Faculty of Arts and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The combined detection of a gravitational-wave signal, kilonova, and short gamma-ray burst (sGRB) from GW170817 marked a scientific breakthrough in the field of multimessenger astronomy. But even before GW170817, there have been a number of sGRBs with possible associated kilonova detections. In this work, we re-examine these 'historical' sGRB afterglows with a combination of state-of-the-art afterglow and kilonova models. This allows us to include optical/near-infrared synchrotron emission produced by the sGRB as well as ultraviolet/optical/near-infrared emission powered by the radioactive decay of r -process elements (i.e. the kilonova). Fitting the light curves, we derive the velocity and the mass distribution as well as the composition of the ejected material. The posteriors on kilonova parameters obtained from the fit were turned into distributions for the peak magnitude of the kilonova emission in different bands and the time at which this peak occurs. From the sGRB with an associated kilonova, we found that the peak magnitude in H bands falls in the range [−16.2, −13.1] (⁠|$95{{\ \rm per\ cent}}$| of confidence) and occurs within |$0.8\!-\!3.6\, \rm d$| after the sGRB prompt emission. In g band instead we obtain a peak magnitude in range [−16.8, −12.3] occurring within the first 18 h after the sGRB prompt. From the luminosity distributions of GW170817/AT2017gfo, kilonova candidates GRB130603B, GRB050709, and GRB060614 (with the possible inclusion of GRB150101B, GRB050724A, GRB061201, GRB080905A, GRB150424A, and GRB160821B) and the upper limits from all the other sGRBs not associated with any kilonova detection we obtain for the first time a kilonova luminosity distribution in different bands. [ABSTRACT FROM AUTHOR]

Copyright of Felsefelogos is the property of Felsefelogos and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article is a letter from the editor of Astronomische Nachrichten (AN), a scientific journal in the field of astronomy. The editor reflects on the journal's long history and the changes in scientific publishing. They express their appreciation for concise and freely accessible research papers that have been peer-reviewed. The editor highlights the recent editorial changes, including the use of a submission platform and open access as part of the European DEAL treaty. The journal welcomes submissions in various fields of astronomy and related studies. The letter concludes with contact information for the editorial team. [Extracted from the article]

This article provides a comprehensive overview of recent developments in the fields of astronomy and geophysics. It covers a wide range of topics, including space exploration, scientific discoveries, and advancements in technology. Some highlights include the UK Space Agency's successful 'Space for Everyone' tour, the addition of Francis Baily's Gold Medal to the Royal Astronomical Society's archive, and the soft landing of India's Chandrayaan-3 on the Moon. The article also discusses various scientific studies and discoveries, such as the identification of black holes near Earth, the observation of Neptune's cloud cycles, and the investigation of seismic activity in a dormant supervolcano. [Extracted from the article]

The Arecibo Observatory first opened in 1963 and has been a marvel of engineering ever since (Figure 1). It has been a monumental instrument for scientific research in the fields of astronomy, planetary radar, ionospheric probing and high-frequency (HF) heating modification, and optical probing of the atmosphere. [ABSTRACT FROM AUTHOR]

Since finalizing of design in 2016, the digital zenith camera of the University of Latvia was involved in a number of test observations as well as field observations at about 70 different sites. The paper presents analysis of observation results, estimation of instrument’s performance and accuracy. Random and systematic error sources are outlined. Impact of anomalous refraction on vertical deflection determination is discussed. Results of adaptation of GAIA reference star catalog for astrometric data reduction are reported.