Tsewang Dorjai | Searcharxiv

arXiv2022

India's first robotic eye for time domain astrophysics: the GROWTH-India telescope

We present the design and performance of the GROWTH-India telescope, a 0.7 m robotic telescope dedicated to time-domain astronomy. The telescope is equipped with a 4k back-illuminated camera giving a 0.82-degree field of view and sensitivity of m_g ~20.5 in 5-min exposures. Custom software handles observatory operations: attaining high on-sky observing efficiencies (>~ 80%) and allowing rapid response to targets of opportunity. The data processing pipelines are capable of performing PSF photometry as well as image subtraction for transient searches. We also present an overview of the GROWTH-India telescope's contributions to the studies of Gamma-ray Bursts, the electromagnetic counterparts to gravitational wave sources, supernovae, novae and solar system objects.

astro-ph.IM↗

arXiv2018

Installation of Solar Chromospheric Telescope at the Indian Astronomical Observatory, Merak

We report the observations of the solar chromosphere from a newly commissioned solar telescope at the incursion site near Pangong Tso lake in Merak (Leh/Ladakh). This new H$_α$ telescope at the Merak site is identical to the Kodaikanal H$_α$ telescope. The telescope is installed in the month of August, 2017 at the Merak site. A 20-cm doublet lens with additional re-imaging optics makes the telescope. A Lyot filter with 0.5~Å~passband isolates the Balmer line of the hydrogen spectra to make the observations of the solar chromosphere. The observations made in H$_α$ wavelength delineates the magnetic field directions at the sunspot and the quiet regions. A CCD detector records the images of the chromosphere with a pixel resolution of 0.27$^{\prime\prime}$ and covers 9.2$^{\prime}$ field-of-view. This telescope has a good guiding system that keeps the FOV in the intended position. We report the development of control software for tuning the filter unit, control detector system, observations, and calibration of the data to make it useful for the scientific community. Some preliminary results obtained from the Merak H$_α$ telescope are also presented. This high altitude facility is a timely addition to regularly available H$_α$ images around the globe.

astro-ph.SR↗