TANSPEC: TIFR-ARIES Near Infrared Spectrometer

Abstract

We present the design and performance of the TANSPEC, a mediumresolution 0.55 − 2.5 µm cryogenic spectrometer and imager, now in operation at the 3.6-m Devasthal Optical Telescope (DOT), Nainital, India. The TANSPEC provides three modes of operation which include, photometry with broad-and narrow-band filters, spectroscopy with short slits of 20 length and different widths (from 0.5 to 4.0 ) in cross-dispersed mode at a resolving power R of ∼2750, and spectroscopy with long slits of 60 length and different widths (from 0.5 to 4.0 ) in prism mode at a resolving power R of ∼100-350. TANSPEC's imager mode provides a field of view of 60 × 60 with a plate scale of 0.245 /pixel on the 3.6-m DOT. The TANSPEC was successfully commissioned during April-May 2019 and the subsequent characterization and astronomical observations are presented here. The TANSPEC has been made available to the worldwide astronomical community for science observations from October 2020.