Astronomical Events Research Articles

Records of Auroras in Arabic Historical Sources: Additional List and Preliminary Analysis

Few studies have collected and analyzed the astronomical events recorded in Arabic literature. In this paper, we present some additional events reported in four Arabic historical sources that could be classified as an aurora. These observations occurred from 9th to 20th century and cover a large geographic area: North Africa, Arabian-Peninsula and Middle-East. Some of them were observed at very low geomagnetic latitude, such as the event seen in Yemen in AD 1919 that can be considered as one of the lowest latitude auroras ever documented by Arabic scholars. In the same Yemenite source, the author describes a twilight phenomenon of 1883 October 03–November 01 which can be considered as an atmospheric-optical phenomenon arising from the major explosive eruptions of Krakatoa in 1883 August 26–27. We also noticed that one of the events which was seen for 7 days coincide probably with the prolonged manifestation of auroras of 1870 September 24–25. Including published records, we compiled a so far most complete catalog of potential auroral candidates in the Arabic sources. This data set can be used in order to study the solar activity variations and magnetic storms in the historical past. One of the interesting auroras was seen in Mecca ($\sim17^{\circ}$ MLAT) in 1872 February 04. This event is further evidence for the equatorward extension of auroral display and the planetary consequences of the great geomagnetic storm of 1872. Finally, it should be underlined that no aurora observations were recorded during the Maunder minimum (MM).

Empowering Science Teachers in Indonesia through NASE Workshops

AbstractYouths and kids in Indonesia since almost two decades ago have been showing significant increase of interest in space sciences, especially astronomy. One of the main factors is due to the annual event of National Science Olympiad which includes Astronomy as the subject. The increasing level of public interest, especially younger generation on astronomical events, such as eclipses, moon sightings, meteor showers has been constantly observed from time to time. Being aware that Astronomy course does not included in primary and secondary education level’s curricula, teachers are somewhat desperate and are not capable to play role as clearing house in science related to space. The IAU Network of Astronomy for School Education Network (IAU-NASE) course was started in 2016 in Machung University, East Java as the pilot project in Indonesia. The course has attracted significant interest from teachers and university staff, especially in East and Middle Java Provinces. Being confident with the enthusiasm of teachers who expressed that NASE course could fulfil their needs to teach and instruct students in a very efficient way, it was organized consecutively at Bandar Lampung, Lampung Province in 2018 and 2019 (hosted by Institut Teknologi Sumatera) and in 2020 at Bandung, West Java Province (hosted by Institut Teknologi Bandung). The most recent NASE course on 21–23 August 2020, conducted in on-line mode, was attended by 74 participants, although primarily aimed at 15 School teachers, and was quite successful. The on-line observational activity turned out to be the most impressive session for the participants. We report and review four years of IAU NASE courses in Indonesia, with various documentation and brief analysis of the positive impact to the teachers and instructors attitude in teaching astronomy at secondary level of education.

Inclusive Eclipse: a sensorial experiencing along Chile

AbstractAn Eclipse is an astronomical event that convenes a large audience. Few days before it, most of the community is aware of the event and the press is activated fully on it. The alignment recovers our most intrinsic human aspects, the curiosity, and enthusiasm for a natural phenomenon. This work is focused to enjoy and perceive it in three different ways: visually, listening, and in an artistic expression.We focused on the construction of more than one hundred LightSound devices, which the main purpose is to record the light intensity and transform it into different tones. Besides, we created an artistic representation of the Eclipse motivated by the ancestral culture of the people residing in the totality zone. This music adds a sensorial joy to the eclipse event.

Young Children’s Ideas About Astronomy

Young children express interest and understanding about science topics through everyday conversations with parents. Little is known about how much interest preschool-aged children show in astronomy. Using a diary report methodology, we asked parents in three communities in coastal California to keep track of conversations with their three to five-year-old children about nature. The communities varied in demographics, including one community with predominantly European-American families, one community with predominantly Latinx families, and one community with families from a variety of backgrounds. Overall, young children showed interest in astronomy through initiation and engagement in conversations about a variety of astronomical objects and events; this was consistent across gender, age, and community. Across all three communities, conversations about astronomy accounted for approximately 15% of the conversations about nature, ranking in the top three most frequent topics for each group. Children initiated the vast majority of conversations with their parents, including those about astronomy. Within astronomy, children were most interested in the sun, moon, stars, and day or night sky. Thus, while science educators may see astronomy as too complex for young children, children observe and comment on astronomical phenomena as part of their everyday life. Finding ways to support educators and parents in talking with children about these observations may productively build on this early astronomy interest and position children for greater understanding and engagement in this domain.

Armenian Astronomical Heritage and Big Data

AbstractAstronomy in Armenia was popular since ancient times and Armenia is rich in its astronomical heritage, such as ancient and medieval Armenian calendars, records of astronomical events by ancient Armenians, the astronomical heritage of the Armenian medieval great thinker Anania Shirakatsi, etc. Armenian astronomical archives have accumulated vast number of photographic plates, films and other careers of observational data. The Digitized Markarian Survey or the First Byurakan Survey, is the most important low-dispersion spectroscopic database. It is one of the rare science items included in UNESCO “Memory of the World” Documentary Heritage list. The Byurakan Astrophysical Observatory (BAO) Plate Archive Project (2015–2021) will result in digitization and storage of some 37,000 astronomical plates and films and in creation of an Electronic Database for further research projects. Based on these data and archives and development of their interoperability, the Armenian Virtual Observatory was created and joined the International Virtual Observatory Alliance.

Semiolinguistics of Protective Communication

The current paper investigates the notion of protective communication represented by systems of signs, texts, rituals which the authors regard as means of neutralizing cognitive constructs, generated by phobias of varying degrees of irrationality. Classification of phobias on psycho- and sociolinguistic grounds allows developing their typology from the point of view of the cause of their origin: supernatural entities (superstition), individual fearful images (prejudice), social suspicion (bias). As the study showed, sacred horror caused by destructive forces of nature, climatic phenomena not subjected to man, and astronomical events gave rise to supernatural, esoteric phobias reflected in superstitions. Biological phobias appeared in response to real dangers, associated with daily human activities, personal imaginary troubles and fears, which generated a system of prejudice invented by man himself. Social interaction of people, with its negative stereotyping and categorization of social space, entailed a wide range of phobias (racial, religious, age, gender, etc,) which turned into social biases. On his way of development, a man tried hard to find protection against phobias of different nature, creating an extensive system of protective means incorporated in religious, magical and intolerant types of discourse, consequently neutralizing superstitions, prejudices and biases in specific genres, verbal and non-verbal signs, texts and rituals of the above mentioned types of discourse.

Equinox in Petra: Land- and Skyscape in the Nabataean Capital

In earlier works, we had shown the actual possibility that the Nabataeans had used the Equinox, or an astronomical event equivalent to this, as an important milestone to control the calendar, stablish festivals and perform pilgrimages to important sacred sites. In this paper we present evidence that this was indeed the case. In a research carried out in Petra in March 2018, equinoctial phenomena were observed and tested at the Urn Tomb, the Obelisks at Jabal Madbah and the sacred area of Al Madras, showing that the actual astronomical Equinox could be observed together with other related phenomena such as the midday between the solstices. Besides, this campaign was used to obtain data in various isolated places in Petra seldom visited by the general public such as the Obodas Chapel, Sidd al Ma’jin, Parcak’s Platform, or the sacred areas on top of Umm al Biyara. These little known monumental sites have also provided interesting results that are described and discussed in this paper.

Simsurvey: estimating transient discovery rates for the Zwicky transient facility

When planning a survey for astronomical transients, many factors such as cadence, filter choice, sky coverage, and depth of observations need to be balanced in order to optimize the scientific gain of the survey. Here we present a software package called simsurvey for simulating the supernova lightcurves that are expected based on a survey strategy, which can then be used to determine the potential for discoveries of each strategy in question. The code is set up in a modular fashion that allows easy modification of small details of the survey and enables the user to adapt it to any survey design and transient template that they wish to use in planning their survey. As an example of its utility, we use simsurvey to simulate the lightcurve of several types of supernovae that the recently started Zwicky Transient Facility (ZTF) is expected to find and compare the results to the discoveries made during its early operations. We conclude that ZTF will find thousands of bright supernovae per year, of which about 10 could potentially be found with two days of explosion. Over the course of three years the survey will obtain lightcurves of about 1800 type Ia supernovae with z < 0.1 that can be used as distance indicators in cosmology if they are spectroscopically classified using additional telescopes. In a comparison to detections from the ZTF public survey, we found good agreement with the numbers of detections expected from the simulations.

Data Challenges as a Tool for Time-domain Astronomy

Data challenges are emerging as powerful tools with which to answer fundamental astronomical questions. Time-domain astronomy lends itself to data challenges, particularly in the era of classification and anomaly detection. With improved sensitivity of wide-field surveys in optical and radio wavelengths from surveys like the Large Synoptic Survey Telescope (LSST) and the Canadian Hydrogen Intensity Mapping Experiment, we are entering the large-volume era of transient astronomy. We highlight some recent time-domain challenges, with particular focus on the Photometric LSST Astronomical Time series Classification Challenge, and describe metrics used to evaluate the performance of those entering data challenges.

Deep Learning for Image Sequence Classification of Astronomical Events

We propose a new sequential classification model for astronomical objects based on a recurrent convolutional neural network (RCNN) which uses sequences of images as inputs. This approach avoids the computation of light curves or difference images. This is the first time that sequences of images are used directly for the classification of variable objects in astronomy. The second contribution of this work is the image simulation process. We generate synthetic image sequences which take into account the instrumental and observing conditions, obtaining a realistic, unevenly sampled, and variable noise set of movies for each astronomical object. The simulated data set is used to train our RCNN classifier. This approach allows us to generate data sets to train and test our RCNN model for different astronomical surveys and telescopes. Moreover, using a simulated data set is faster and more adaptable to different surveys and classification tasks. We aim to build a simulated data set whose distribution is close enough to the real data set, so that fine tuning could match the distributions. To test the RCNN classifier trained with the synthetic data set, we used real-world data from the High cadence Transient Survey (HiTS), obtaining an average recall of 85%, improved to 94% after performing fine tuning with 10 real samples per class. We compare the results of our RCNN model with those of a light curve random forest classifier. The proposed RCNN with fine tuning has a similar performance on the HiTS data set compared to the light curve random forest classifier, trained on an augmented training set with 10 real samples per class. The RCNN approach presents several advantages in an alert stream classification scenario, such as a reduction of the data pre-processing, faster online evaluation, and easier performance improvement using a few real data samples. The results obtained encourage us to use the proposed method for astronomical alert broker systems that will process alert streams generated by new telescopes such as the Large Synoptic Survey Telescope.

Jet Geometry and Rate Estimate of Coincident Gamma-Ray Burst and Gravitational-wave Observations

Abstract Short gamma-ray burst (SGRB) progenitors have long been thought to be coalescing binary systems of two neutron stars (NSNS) or a neutron star and a black hole. The 2017 August 17th detection of the GW170817 gravitational-wave (GW) signal by Advanced LIGO and Advanced Virgo in coincidence with the electromagnetic observation of the SGRB GRB 170817A confirmed this scenario and provided new physical information on the nature of these astronomical events. We use SGRB observations by the Neil Gehrels Swift Observatory Burst Alert Telescope and GW170817/GRB 170817A observational data to estimate the detection rate of coincident GW and electromagnetic observations by a GW detector network and constrain the physical parameters of the SGRB jet structure. We estimate the rate of GW detections coincident with SGRB electromagnetic detections by the Fermi Gamma-ray Burst Monitor to be between ∼0.1 and ∼0.6 yr−1 in the third LIGO-Virgo observing run and between ∼0.3 and ∼1.8 yr−1 for the LIGO-Virgo-KAGRA network at design sensitivity. Assuming a structured model with a uniform ultrarelativistic jet surrounded by a region with power-law decay emission, we find the jet half-opening angle and the power-law decay exponent to be θ c ∼ 7°–22° and s ∼ 5–30 at a 1σ confidence level, respectively.

Effect of SiC particle additions on the corrosion resistance, thermodynamic stability and surface morphology of Mg–Al alloy in sulphate and chloride media

Application of magnesium materials continues to grow due to their high specific strength and excellent castability. However, low corrosion resistance limits their application in aqueous electrolytes. Understanding their corrosion behaviour is key to the improvement of their corrosion resistance. The effect of SiC at specific weight content on the corrosion polarization behaviour, surface morphology and thermodynamic stability of Mg–Al alloy in 0.05 M H2SO4 and 3.5% NaCl electrolytes was studied through potentiodynamic polarization, optical microscopy and open circuit potential measurement techniques. Results showed SiC additions significantly and progressively decreased the corrosion rate of Mg–Al alloy in both electrolytes due to decrease in the exposed area for the formation of porous Mg(OH)2 on the alloy surface. At 0% SiC wt content the corrosion rate values are 4.930 mm y−1 and 0.259 mm y−1 while at 10% SiC wt content the corresponding values have decreased to 0.429 mm y−1 and 0.090 mm y−1. Anodic potential displacement occurred in H2SO4 at all SiC% wt contents leading to rapid destruction of the protective oxide and absence of passivation characteristics. Mg–Al alloy demonstrated sufficient passivation after anodic polarization in NaCl solution due to the localized electrochemical action of chlorides. Morphological representations showed severe general surface deterioration on Mg–Al specimens from H2SO4 and visible localized deterioration on specimens from NaCl in the absence of SiC. The extent of deterioration on the morphology of Mg–Al alloy decreased at 2.5% and 10% SiC wt Without applied potentials Mg–Al alloy in H2SO4 with SiC was relatively more electropositive due to stability of its protective oxide compare to specimens with SiC. In NaCl solution, the reactivity of chlorides hindered the formation of the protective oxide resulting in more electronegative potential plots. However, the plots of Mg–Al at 2.5% and 10% SiC wt content where thermodynamically unstable due to visible potential transients.

Possibility of astronomical phenomena to be used to support tourism industry

Several astronomical events in the past have shown their potential to attract tourists. This motivates some astronomers and tourism activists to create tourism related events when an interesting astronomical phenomenon occur. The most attractive recent astronomical phenomenon for tourists was the solar eclipse as was proven during the total solar eclipse of March 9, 2016. Similarly, other phenomena such as the lunar eclipse, meteor shower, Mars Opposition have some potential to be exploited as events to attract tourists. Belitong Geopark had organized a sky observation event, for example super blue blood moon event on January 31, 2018 and Mars opposition event on July 21, 2018. It successfully drew attention far and wide, but it needed more effort and creativity to make these events more attractive and marketable. Other cultural heritage sites which contain inherent astronomical tie-in knowledge, such as Borobudur Temple, are also strong prospective to be developed for astro-tourism destinations. In the future, astro-tourism permanent facilities may be developed, for example, sky observation facilities for amateurs in Dark Sky National Park, near Mount Timau National Observatory in Kupang, East Nusa Tenggara Province.

Possibility of a Coordinated Signaling Scheme in the Galaxy and SETI Experiments

We discuss a Galaxy-wide coordinated signaling scheme with which a SETI observer needs to examine a tiny fraction of the sky. The target sky direction is determined as a function of time, based on high-precision measurements of a progenitor of a conspicuous astronomical event such as a coalescence of a double neutron star binary. In various respects, such a coordinated scheme would be advantageous for both transmitters and receivers, and might be widely prevailing as a tacit adjustment. For this scheme, the planned space gravitational-wave detector LISA and its follow-on missions have a potential to narrow down the target sky area by a factor of $10^{3\textit{-}4}$, and could have a large impact on future SETI experiments.

Indigenous Knowledge Systems for Local Weather Predictions: A Case of Mukonchi Chiefdom in Zambia

The purpose of the study was to unravel constituents of the indigenous knowledge systems (IKS) and appreciate people&amp;rsquo;s experiences in predicting the weather in daily undertakings. The objectives of the study were; to identify factors or systems used, establish the knowledge used in predicting the weather and compare the indigenous and current scientific method of predicting the weather. Qualitative and quantitative research designs were used. Primary data was collected through semi structured, face-to-face and in-depth interviews. This was complemented by secondary data collected through desk reviews of relevant published materials. The findings reveal that indigenous knowledge systems have been employed by people of Mukonchi chiefdom since time immemorial. There has also been reliance on IKS to make decisions pertaining to livelihoods such as agricultural activities. However, IKS in the area remains undocumented. Observation of several occurrences in combination or singularly relating to plants, animals, insects and astronomical events were factors of significant importance in the knowledge of weather extrapolation. Elements such as age, frequency of use of the IKS and level of education were seen to be of momentous prominence in utilisation of the indigenous knowledge as modern means of weather forecasting which are applicable to local community environment.

異分野連携研究における研究基盤データ構築への市民参加の可能性:参加 型ワークショップ「古典オーロラハンター」を事例として

異分野連携研究における研究基盤データ構築への市民参加の可能性:参加 型ワークショップ「古典オーロラハンター」を事例として

Statistical Discrimination of RFI and Astronomical Transients in 2-bit Digitized Time Domain Signals

We investigate the performance of the generalized Spectral Kurtosis (SK) estimator in detecting and discriminating natural and artificial, very short duration transients in the 2-bit sampling time domain Very-Long-Baseline Interferometry (VLBI) data. We demonstrate that, while both types of transients may be efficiently detected, their natural or artificial nature cannot be distinguished if only a time domain SK analysis is performed. However, these two types of transients become distinguishable from each other in the spectral domain, after a 32-bit FFT operation is performed on the 2-bit time domain voltages. We discuss the implication of these findings on the ability of the Spectral Kurtosis estimator to automatically detect bright astronomical transient signals of interests, such as pulsar or fast radio bursts (FRB), in VLBI data streams that have been severely contaminated by unwanted radio frequency interference.

An Embedded X-Ray Source Shines through the Aspherical AT 2018cow: Revealing the Inner Workings of the Most Luminous Fast-evolving Optical Transients

Abstract We present the first extensive radio to γ-ray observations of a fast-rising blue optical transient, AT 2018cow, over its first ∼100 days. AT 2018cow rose over a few days to a peak luminosity L pk ∼ 4 × 1044 erg s−1, exceeding that of superluminous supernovae (SNe), before declining as L ∝ t −2. Initial spectra at δt ≲ 15 days were mostly featureless and indicated large expansion velocities v ∼ 0.1c and temperatures reaching T ∼ 3 × 104 K. Later spectra revealed a persistent optically thick photosphere and the emergence of H and He emission features with v ∼ 4000 km s−1 with no evidence for ejecta cooling. Our broadband monitoring revealed a hard X-ray spectral component at E ≥ 10 keV, in addition to luminous and highly variable soft X-rays, with properties unprecedented among astronomical transients. An abrupt change in the X-ray decay rate and variability appears to accompany the change in optical spectral properties. AT 2018cow showed bright radio emission consistent with the interaction of a blast wave with v sh ∼ 0.1c with a dense environment ( for v w = 1000 km s−1). While these properties exclude 56Ni-powered transients, our multiwavelength analysis instead indicates that AT 2018cow harbored a “central engine,” either a compact object (magnetar or black hole) or an embedded internal shock produced by interaction with a compact, dense circumstellar medium. The engine released ∼1050–1051.5 erg over ∼103–105 s and resides within low-mass fast-moving material with equatorial–polar density asymmetry (M ej,fast ≲ 0.3 M ☉). Successful SNe from low-mass H-rich stars (like electron-capture SNe) or failed explosions from blue supergiants satisfy these constraints. Intermediate-mass black holes are disfavored by the large environmental density probed by the radio observations.

Antikythera mechanism – A compound epicyclic gearing for Venus

One undeniable characteristic of Antikythera mechanism is the complex gear arrangements that generously have been used by the constructor. He succeeded the best combination of integer numbers to reach the maximum accuracy, no matter the number of the gears he used for it. One representative example is the “moon train” consisted of eleven meshing gears which he used to simulate the non-uniform lunar motion. Someone could say that the constructor preferred the complexity for the sake of accuracy. Many Scholars, believe that the mechanism could be a kind of planetarium. In that case, there is a possibility of a more complex mechanical subsystem comprised of more imaginative and specialized gear arrangements. The latest decoded inscriptions on the mechanism's surfaces, are referred to planets (Inferiors and Superiors) and show records of astronomical events. The lack of physical evidence of this planetary construction prevents its conception, but on the other hand, challenges the researchers to discover the inimitable thought of its creator. Nevertheless, fitting this excess gearing in a limited space of a compact construction like Antikythera mechanism is really a puzzler. The planetary subsystem which will complete the mechanism should stand out for the maximum possible measurement accuracy and the best space management. This research proposes a feasible epicyclic gearing specialized for a compact planetary construction achieving the highest possible accuracy.

¿Atrapando el Solsticio? Un análisis crítico de la orientación de los templos de Deir el-Bahari

The temples of Deir el-Bahari were studied in earlier campaigns carried out during the last decade within the framework of the Archaeoastronomy Mission of Ancient Egypt; in particular those of Mentuhotep II and Hatshepsut. Although they seem to belong to the family of temples oriented to the rising sun at the winter solstice, this orientation was not as precise as would be expected for temples of such importance. Therefore, after resuming work in Egypt, it was decided to propose alternative hypotheses that could explain the deviations of these two temples to the south and north of the solsticial line, respectively. It is difficult to imagine that they were mere design errors. In December 2017, further fieldwork was carried out in Thebes, in particular at Deir el-Bahari, and observations and measures were made on site during the winter solstice itself, documenting this phenomenon. The verifications carried out seem to confirm some new approaches. On the one hand, the memorial temple of Mentuhotep II could be diverted c. 2º to the south so that there would be a lighting effect during the winter solstice in the chapel closing the complex at the base of the cliff. This would be an astronomical event that could be related to the Wepet Renpet (New Year) at that period (11th Dynasty). On the other hand, the Temple of Millions of Years of Hatshepsut could be oriented towards sunrise on another unique date of the civil calendar during the reign of this sovereign. All in all, astronomical orientations at the site could relate to key dates in the civil calendar at the time when the temples were built.