Observations with the 3.6 meter Devasthal Optical Telescope

TL;DR

The 3.6 meter Devasthal Optical Telescope has demonstrated high-quality optical and near-infrared observations, detecting faint celestial objects and resolving binary stars, confirming its performance is comparable to global telescopes and suitable for advanced astrophysical research.

Contribution

This paper reports the first observational results and performance assessment of the 3.6 meter Devasthal Optical Telescope, highlighting its capabilities in detecting faint objects and resolving close binaries.

Findings

Detected stars up to magnitude 25 in optical bands.

Resolved a binary star with 0.4 arc-sec separation.

Achieved sub-arcsecond sky imaging at optical and NIR wavelengths.

Abstract

The 3.6 meter Indo-Belgian Devasthal optical telescope (DOT) has been used for optical and near-infrared (NIR) observations of celestial objects. The telescope has detected stars of B = 24.5+-0.2; R = 24.6+-0.12 and g = 25.2+-0.2 mag in exposure times of 1200, 4320 and 3600 seconds respectively. In one hour of exposure time, a distant galaxy of 24.3+-0.2 mag and point sources of ~ 25 mag have been detected in the SDSS i band. The NIR observations show that stars up to J = 20+-0.1; H = 18.8+-0.1 and K = 18.2+-0.1 mag can be detected in effective exposure times of 500, 550 and 1000 seconds respectively. The nbL band sources brighter than ~9.2 mag and strong (> 0.4 Jy) PAH emitting sources like Sh 2-61 can also be observed with the 3.6 meter DOT. A binary star having angular separation of 0.4 arc-sec has been resolved by the telescope. Sky images with sub-arc-sec angular resolutions are observed with the telescope at wavelengths ranging from optical to NIR for a good fraction of observing time. The on-site performance of the telescope is found to be at par with the performance of other similar telescopes located elsewhere in the world. Due to advantage of its geographical location, the 3.6 meter DOT can provide optical and NIR observations for a number of front line Galactic and extra-galactic astrophysical research problems including optical follow up of GMRT and AstroSat sources and optical transient objects.