U. S. KAMATH
Articles written in Journal of Astrophysics and Astronomy
Volume 37 Issue 4 December 2016 Article ID 0038 Review
Stars and planetary systems are formed out of molecular clouds in the interstellar medium. Although the sequence of steps involved in star formation are generally known, a comprehensive theory which describes the details of the processes that drive formation of stars is still missing. The Square Kilometre Array (SKA), with its unprecedented sensitivity and angular resolution, will play a major role in filling these gaps in our understanding. In this article, we present a few science cases that the Indian star formation community is interested in pursuing with SKA, which include investigation of AU-sized structures in the neutral ISM, the origin of thermal and non-thermal radio jets from protostars and the accretion history of protostars, and formation of massive stars and their effect on the surrounding medium.
Volume 42 All articles Published: 22 April 2021 Article ID 0011
A near-infrared photometer based on an InGaAs PIN photodiode and the filter set recommended by Infrared Working Group (IRWG) have been designed and built. It is mounted on the 1-m Carl–Zeiss telescope at the Vainu Bappu Observatory (VBO) in Kavalur, India. The main science goal is to observe bright sources (<5 magnitude) in the iZ, iJ and iH photometric bands. A discussion of the instrument and on-telescope performance during first-light tests are presented in this paper.
Volume 43 All articles Published: 26 February 2022 Article ID 0013
The photometric accuracy in the near-infrared (NIR) wavelength range (0.9–2.6 $\mu$m) is strongly affected by the variability of atmospheric transmission. The Infrared Working Group (IRWG) has recommendedfilters that help alleviate this issue and provide a common standard of NIR filtersets across different observatories. However, accurate implementation of these filters are yet to be available to astronomers. In the meantime, InGaAs based detectors have emerged as a viable option for small and medium telescopes. The present work explores the combination of IRWG filtersets with InGaAs detectors. A few commercially available filtersets that approximate the IRWG profile are compared. Design of more accurate IRWG filtersets suitable for the InGaAs sensitivity range is undertaken using an open-source filter design software – OpenFilters. Along with the photometric filters iZ, iJ and iH, design of a few useful narrow band filters is also presented. These filters present opportunities for small and medium telescopes for dedicated long-termobservation of interesting infrared sources.
Volume 43 All articles Published: 31 May 2022 Article ID 0032 OBSERVATIONAL FACILITIES
G. C. ANUPAMA G. MAHESWAR S. SRIRAM T. SIVARANI P. S. PARIHAR S. NAGABHUSHAN DORJE ANGCHUK S. BARWAY B. C. BHATT R. BANYAL ALIKHAN BASHEER PRASANNA DESHMUKH DEVIKA DIVAKAR TSEWANG DORJAI ARUNA GOSWAMI K. V. GOVINDA SONAM JORPHAIL U. S. KAMATH MADAN MOHAN KEMKAR TASHI TSERING MAHAY S. MUNEER C. MUTHUMARIAPPAN SHANTIKUMAR SINGH NINGOMBAM G. PANDEY B. E. REDDY D. K. SAHU D. S. SANDEEP RAMYA SETHURAM C. S. STALIN S. SUBRAMANIAN STANZIN TSEWANG A. SUBRAMANIAM
An observatory class national large optical-IR telescope (NLOT), is proposed to be built and located in the country. The telescope consists of a 10–12 m segmented primary. In order to cater to a diversity of observational programs, the telescope is designed with high throughput in both the optical and IRregions (0.3–5 $\mu$m). It should perform reasonably well up to 30 $\mu$m. The telescope and instruments should have remote operations capability, allowing for the queue as well as classical scheduling and high reliability and robustness. This article provides a brief description of the science cases that drive the telescope requirements, activities related to optics design and some thoughts on the instruments.
Volume 43, 2022
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