Indian Astronomy Research Articles

A High-resolution Spectrograph at a Metre-class Telescope at Devasthal: What Can Be Gained?

The Indo-Belgian bilateral project titled “Belgo-Indian Network for Astronomy and Astrophysics (BINA)” is an excellent initiative to spark scientific collaboration between Belgian and Indian astronomers. The Belgian university, KU Leuven, owns and operates the semi-robotic Mercator telescope - a 1.2m telescope stationed at the Roque de los Muchachos observatory on the island of La Palma. This telescope is equipped with the High-Efficiency and high-Resolution Mercator Echelle Spectrograph (HERMES). This contribution aims to discuss a long-standing idea - what would BINA, and by extension the entire Indian astronomical community, gain with the addition of a similar 1-m class telescope with a high-resolution spectrograph in Devasthal.

Recent Observations of Peculiar Gamma-Ray Bursts Using the 3.6-m Devasthal Optical Telescope (DOT)

India has been actively involved in the follow-up observations of optical afterglows of gamma-ray bursts (GRBs) for more than two decades, using the country’s meter-class facilities such as the 1.04m Sampurnanand Telescope, 1.3m Devasthal Fast Optical Telescope, 2.01 m Himalayan Chandra Telescope along with many others in the country, utilizing the longitudinal advantage of the place. However, since 2016, Indian astronomers have embarked on a new era of exploration by utilizing the country’s largest optical telescope, the 3.6-m Devasthal Optical Telescope (DOT) at the Devasthal Observatory of ARIES Nainital. This unique telescope has opened up exciting opportunities for transient study. Starting from the installation itself, the DOT has been actively performing the target of opportunity (ToO) observations, leading to many interesting discoveries. Notable achievements include the contributions towards the discovery of long GRB 211211A arising from a binary merger, the discovery of the most delayed optical flare from GRB 210204A along with the very faint optical afterglow (fainter than 25 mag in g-band) of GRB 200412B. We also successfully observed the optical counterpart of the very-high-energy (VHE) detected burst GRB 201015A using DOT. Additionally, DOT has been used for follow-up observations of dark and orphan afterglows, along with the observations of host galaxies associated with peculiar GRBs. More recently, DOT’s near-IR follow-up capabilities helped us to detect the first near-IR counterpart (GRB 230409B) using an Indian telescope. In this work, we summarise the recent discoveries and observations of GRBs using the 3.6-m DOT, highlighting the significant contributions in revealing the mysteries of these cosmic transients.

A Study of Ancient Indian Astronomy through Architectural Marvels

Ancient Indian astronomy has a rich legacy that spans millennia, encompassing intricate observations, advanced calculations, and skillful implementations. This review article explores the intersection of astronomy and architectural marvels in ancient India. By examining the architectural marvel, the profound astronomical knowledge embedded within its design and construction is inspected. The study aims to unveil the celestial alignments, geometric patterns, and symbolic representations reflecting the deep understanding of cosmic phenomena of ancient Indian astronomers and architects. With this review, through a comprehensive analysis of the temple’s architectural elements, it is expected to gain insights into the intricate methods employed by ancient Indians to encode astronomical principles into monumental structures and the cultural significance of these celestial pursuits.

A Study of Ancient Indian Astronomy through Architectural Marvels

Ancient Indian astronomy has a rich legacy that spans millennia, encompassing intricate observations, advanced calculations, and skillful implementations. This review article explores the intersection of astronomy and architectural marvels in ancient India. By examining the architectural marvel, the profound astronomical knowledge embedded within its design and construction is inspected. The study aims to unveil the celestial alignments, geometric patterns, and symbolic representations reflecting the deep understanding of cosmic phenomena of ancient Indian astronomers and architects. With this review, through a comprehensive analysis of the temple's architectural elements, it is expected to gain insights into the intricate methods employed by ancient Indians to encode astronomical principles into monumental structures and the cultural significance of these celestial pursuits.

THE ROLE OF SINDHIND ZIJ AS THE FIRST ISLAMIC ASTRONOMICAL CALCULATION TABLE IN INDIAN CIVILIZATION

Astronomy has developed in India since prehistoric times. However, astronomy’s first work appeared during the Vedanga Jyotisa era, written by Lagadha, the oldest literary book in India. Using qualitative methods with a library research approach, it was found that Indian astronomers researched Astronomy and wrote books. One of the books that first made Muslim scientists interested in the world of astronomy was the book Brāhmasphuṭasiddhānta, which was translated into Arabic by Al-Fazari (d. 796 AD) during the Caliphate of Al-Manṣūr from the Abbasid dynasty. Al-Fazari (d. 796 AD) became the first Muslim astronomer to compile Zij, with his calculations converted into the Hijri Calendar. After Al-Fazari (d. 796 AD) collected this Zij, other Zijs were born, which became the forerunners for the composition of the epimeris and other counts. Around the beginning of the 11th century, Al-Biruni (973-1048 AD) spread da'wah to India and introduced the study of Islamic astronomy in India.

Conjunction of planets: procedures and examples from Indian astronomy texts

Conjunction of planets: procedures and examples from Indian astronomy texts

Planetary nodes and apses in the Sūrya-Siddhānta

There are a few aspects of Indian astronomy that border on the implausible, and none more so than the nodal and apsidal movements of planetary orbits as specified in the Sūrya-Siddhānta. In this paper we examine some aspects of this data in the light of modern astronomy. Given the very-slow rates of motion specified for these two parameters, we speculate that this data might be heliocentric (as opposed to geocentric), and proceed with that assumption in this paper. It is determined that while this assumption proves true for the outer planets (Mars, Jupiter and Saturn), it does not conform well with the inner planets (Mercury and Venus). It is also determined that while the directions specified in the Sūrya-Siddhānta for these subtle motions are correct, the rates of motion given are slower by a couple orders of magnitude compared to actuality. Further analysis also appears to confirm that the data is genuine, and the epoch of the data is likely many thousands of years old.

Plans for building a prototype SKA regional centre in India

In order to deliver the full science potential of the Square Kilometer Array (SKA) telescope, several SKA Regional Centres (SRCs) will be required to be constructed in different SKA member countries around the world. These SRCs will provide high performance compute and storage for the generation of advanced science data products from the basic data streams generated by the SKA Science Data Handling and Processing system, critically necessary to the success of the key science projects to be carried out by the SKA user community. They will also provide support to astronomers to enable them to carry out analysis on very large SKA datasets. Construction of such large data centres is a technical challenge for all SKA member nations. In such a situation, each country plans to construct a smaller SRC over the next few years (2022 onwards), known as a proto-SRC. In India, we propose to construct a proto-SRC which will be used for the analysis of data from SKA pathfinders and precursors with strong Indian involvement such as uGMRT, Meerkat and MWA. We describe our thinking on some aspects of the the storage, compute and network of the proto-SRC and how it will be used for data analysis as well as for carrying out various simulations related to SKA key science projects led by Indian astronomers. We also present our thoughts on how the proto-SRC plans to evaluate emerging hardware and software technologies and to also begin software development in areas of relevance to SKA data processing and analysis such as algorithm implementation, pipeline development and data visualisation software.

Probing early Universe through redshifted 21-cm signal: Modeling and observational challenges

Cosmic dawn (CD) and the epoch of reionization (EoR) are the most important parts of cosmic history during which the first luminous structures emerged. These first objects heated and ionized the neutral atomic hydrogen in the intergalactic medium. The redshifted 21-cm radiation from the atomic hydrogen provides an excellent direct probe to study the evolution of neutral hydrogen (Hi) and thus reveal nature of the first luminous objects, their evolution and role in this last phase transition of the Universe and formation and evolution of the structures thereafter. Direct mapping of the Hi density during the CD–EoR is rather difficult with the current and forthcoming instruments due to stronger foreground and other observational contamination. The first detection of this redshifted Hi signal is expected to be done through statistical estimators. Given the upmost importance of the detection and analysis of the redshifted 21-cm signal, physics of CD–EoR is considered as one of the objective of the upcoming SKA-low telescope. This paper summarizes the collective effort of Indian astronomers to understand the origin of the redshifted 21-cm signal, sources of first ionizing photons, their propagation through the IGM, various cosmological effects on the expected 21-cm signal, various statistical measures of the signal like power spectrum, bispectrum, etc. A collective effort on detection of such signal by developing estimators of the statistical measures with rigorous assessment of their expected uncertainties, various challenges like that of the large foreground emission and calibration issues are also discussed. Various versions of the detection methods discussed here have also been used in practice with the Giant Meterwave Radio Telescope with successful assessment of the foreground contamination and upper limits on the matter density in reionization and post-reionization era. The collective efforts compiled here has been a large part of the global effort to prepare proper observational technique, analysis procedure for the first light of the CD–EoR through the SKA-low.

Reassessing European impressions of Indian astronomy (1750–1850)

The early colonial rule in India was characterised by, among other things, an increasing interest in various disciplines of Indian knowledge traditions. Within the vast array of Indian knowledge systems, the astronomical sciences and corresponding Sanskrit treatises attracted the attention of many prominent orientalists such as Henry Thomas Colebrooke and John Warren. This essay is an attempt to highlight and critically examine some prominent eighteenth century accounts of Indian astronomy.

Astronomy and Calendrical Science in Early Mikkyō in Japan: Challenges and Adaptations

This study examines the use, adaptation, modification and omission of astronomical and calendrical elements in early Japanese Mikkyō (ninth century) in large part from the perspective of exact sciences. Shingon and Tendai inherited a Sinicized system of Indian astrology from their respective beginnings, but the significance of this fact in the study of Japanese religions is underrecognized despite the reality that astrology was both studied and technically required in Mikkyō. This study will examine how Mikkyō negotiated the demand for orthopraxical use of Indian models with the contingent realities of only possessing in practice a Chinese calendar and system of observational astronomy. Japanese monks were compelled to observe Indian astrology according to their own scriptures, which by extension necessitated knowledge of Indian astronomy, but substitutions and omissions had to be made in the absence of the required resources and knowledge.

The Brilliance of Indian Astronomers and Mathematicians of Kerala School during Medieval Period

This paper is an effort to assemble in a synchronized manner, the brilliant contribution of the illustrious Keralian Mathematician and Astronomers, since Vararuchi (fourteenth century C.E) to Medieval Periods Madhava (C.1340- 1425), Paramesvara (C.1360- 1455), Nilakantha Somayaji (C. 1444 -1545) and his followers. It would entail that Indian Mathematics was well ahead by 350 to 400 years in comparison to European contributors Newton, Leibnitz, Taylor and others.

Chasing change: the lasting legacy of India's 1871 eclipse

Abstract The total eclipse of the Sun on 12 December 1871 offered a timely test of new astrophysical methods – and a priceless opportunity for one Indian astronomer.

Measuring Citation Diffusion of Selective Indian Physics and Astronomy Journals by Citation Swing Factor (CSF)

Measuring Citation Diffusion of Selective Indian Physics and Astronomy Journals by Citation Swing Factor (CSF)

Adaptation to early modern heliocentrism in technical vocabulary of Sanskrit mathematical astronomy

ABSTRACT This article examines aspects of Indian ‘colonial science’ in mathematical astronomy viewed as an active development within the Sanskrit learned tradition of jyotiḥśāstra, rather than merely a passive reception of or reaction to the scientific disciplines of the colonizers. It thus considers a particular Sanskrit knowledge system as the central representative of science in order to explore how contact with different knowledge systems and their institutional and political contexts affected and finally terminated its development as a scientific tradition. The article identifies three distinct though overlapping strands within the long tradition of classical Sanskrit mathematical astronomy – siddhāntic astronomy, which synthesized Vedic calendric and predictive models and Vedāṅga texts with Hellenistic spherical astronomy and Indo-Greek horoscopy; the encounter between siddhāntic astronomy and Greco-Islamic Ptolemaic astronomy from Arabic and Persian sources, which produced a new textual form, the Sanskrit koṣṭhaka/sāraṇī or numeric-array table-text, a popular genre of the second millennium; and the meeting of Indian astronomy and European heliocentric (or crypto-heliocentric) theories, c. 1700, which produced Sanskrit translations of Latin texts. It argues that Sanskrit technical writing in the field accommodated new cosmological concepts, including ones from Latin texts, and integrated them within its own familiar mathematical and expository models.

Exploring 120 years of Indian physics and astronomy journals

This paper traces one hundred and twenty years journey of Indian physics and astronomy journals. Of the 122 journals that have been published since 1902, 36 journals have ceased publication. The oldest physics related article was published in 1788 in Asiatick Researches , the first Indian research periodical. The oldest Indian astronomy journal Publications of the Maharaja Takhtasingji Observatory came into being in 1902 from Pune and ceased in 1912 . The oldest Indian physics journal Bhoutika Kalanidhi or The Treasury of the Physical Sciences started in the year 1911 from Madras (present-day Chennai) and ceased in 1919. In all, 53% of journals belong to broad science discipline but publish articles on physics and astronomy regularly along with other major science disciplines followed by 35% and 12% journals strictly belong to the subject areas, physics, and astronomy respectively. It is observed that nearly 50% of journals are indexed by the Indian Citation Index, while 20% of journals are indexed by the Indian Citation Index, Scopus, and Web of Science. Also, 30% of journals are not indexed by any citation database. In the 120 year period, the highest number of seven journals came into being in the year 2012.

Evaluation of fractional clear sky over potential astronomical sites

ABSTRACT The estimation of the night-time cloud fraction (CF) is found to be one of the key parameters for evaluating the number of useful nights at an astronomical site. This work evaluates useful astronomical night-time observation over eight sites using a minimum threshold of CF from 21 years (2000–2020) of ground-based hourly visual and daily satellite data along with 41 years (1980–2020) of long-term hourly reanalysis data. The estimated number of photometric nights is underestimated by 8–24 per cent using the reanalysis data at Indian Astronomical Observatory-Hanle in comparison with the visual observations, while the estimated number of spectroscopic nights is 70–75 per cent per year and in good agreement with the visual observations. Among the astronomical sites, Paranal is found to be the best for astronomical observations, with 87 per cent spectroscopic nights per year. On the other hand, Hanle, Ali and Devasthal, located in the Himalayan region, exhibit an average of 68–78 per cent spectroscopic nights per year based on long-term reanalysis data, while Merak exhibits 61–68 per cent spectroscopic nights per year. Vertical profiles and global horizontal distributions for CF and related variable parameters are further compared among the sites. Global CF trends based on 41 years of reanalysis data show a decreasing tendency over most land regions and an increasing tendency over oceanic regions as well as over the Sahara desert, Middle East, and Indian subcontinent along the adjacent Tibetan Plateau. Such different CF trends between the ocean and land regions are thought to be the result of differential surface warming and water vapour changes associated with climate change.

Examining Amoghavajra’s flat-earth cosmology: religious vs. scientific worldviews in Buddhist astrology

ABSTRACT This study examines the cosmology of the monk Amoghavajra (Bukong 不空; 705–774), as outlined in his astrological manual, the Xiuyao jing 宿曜經 (Sūtra of Lunar Stations and Planets), as well as its historical background and context, in relation to classical Buddhist models of Mt. Meru and the Four Continents in the Āgamas and Abhidharma. These models all use a flat-earth model, in contrast to the spherical-earth model utilized within classical Indian astronomy. This study shows that although the spherical model was known in Chinese from at least the early eighth century via the Jiuzhi li 九執曆 (*Navagraha-karaṇa), a translation of an Indian astronomical treatise, Amoghavajra consciously adopted the flat-earth model in his cosmology, yet at the same time he was willing to introduce new astronomical elements, such as the planets and the zodiac signs. It is argued that Amoghavajra’s cosmology constitutes an intriguing example in Buddhist history of a religious worldview taking precedence over a scientific one, yet at the same time it is demonstrated that Chinese Buddhist literature was not averse to incorporating some scientific astronomical elements before, during and after Amoghavajra’s time.

Multiband Transit Follow-up Observations of Five Hot Jupiters with Critical Noise Treatments: Improved Physical Properties

Abstract The most challenging limitation in transit photometry arises from the noises in the photometric signal. In particular, the ground-based telescopes are heavily affected by the noise due to perturbation in the Earth’s atmosphere. Use of telescopes with large apertures can improve the photometric signal-to-noise ratio to a great extent. However, detecting a transit signal out of a noisy light curve of the host star and precisely estimating the transit parameters call for various noise reduction techniques. Here, we present multiband transit photometric follow-up observations of five hot Jupiters e.g., HAT-P-30 b, HAT-P-54 b, WASP-43 b, TrES-3 b, and XO-2 N b, using the 2 m Himalayan Chandra Telescope at the Indian Astronomical Observatory, Hanle, and the 1.3 m J. C. Bhattacharya Telescope at the Vainu Bappu Observatory, Kavalur. Our critical noise treatment approach includes techniques such as wavelet denoising and Gaussian process regression, which effectively reduce both time-correlated and time-uncorrelated noise components from our transit light curves. In addition to these techniques, use of our state-of-the-art model algorithms have allowed us to estimate the physical properties of the target exoplanets with a better accuracy and precision compared to the previous studies.

RAGOONATHA CHARRY AND OBSERVATIONS OF THE TOTAL SOLAR ECLIPSE OF 1868 FROM VANPURTHY (WANPARTHY), INDIA

The eclipse of 18 August 1868, often called as the 'The Great Indian Eclipse', and described as a 'watershed event', took place at a time when what can be called as 'old eclipse studies' was fading and the era of solar physics, using spectroscopy, photography, polarimeter and so on, was starting to bloom. It was also a notable event in the history of the emergence of modern astronomy and astrophysics in India. Although observations of eclipses were conducted earlier, it was in 1868 that the Madras Observatory organised an eclipse expedition, and for the first time an Indian astronomer led a modern astronomical eclipse expedition. Ragoonatha Charry, the First (head) Assistant at the Observatory led a team of astronomy enthusiasts to observe the eclipse from Vanpurthy (Wanparthy) situated near the central line of the path of totality. While the significant scientific breakthroughs, such as the discovery of helium and the spectral characteristics of prominences and the corona, were made during the 1868 eclipse mainly by the British and French expeditions at Guntur and Masulipatnam, this expedition led by an Indian astronomer, had an impact on the public imagination and subsequently on calendar reform in southern India. In this paper, we focus mainly on Ragoonatha Charry's expedition to Vanpurthy, a principality under the dominion of the Nizam of Hyderabad state. We examine the preparatory scientific work done by Ragoonatha Charry, associated personnel on the expedition, the selection and establishment of their observing station, the scientific instruments that they used, the observations that they made, and the impact that this particular eclipse had on the public imagination.