Abstract:
We present the design and performance of the TANSPEC, a medium-resolution 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 narrowband 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−1 on the 3.6 m DOT. The TANSPEC was successfully commissioned during 2019 April–May, and
the subsequent characterization and astronomical observations are presented here. The TANSPEC was made available
to the worldwide astronomical community for science observations from 2020 October.
