TIFR-ARIES Near Infrared Spectrometer (TANSPEC) for 3.6-m Devasthal Optical Telescope (DOT)

Abstract:

TIFR-ARIES Near Infrared Spectrometer (TANSPEC) is being built in collaboration with MKIR, Hawaii for the ARIES 3.6-m Devasthal Optical Telescope (DOT), Nainital. It will be a unique spectrograph which provides simultaneous wavelength coverage from 600 nm to 2540 nm, with a resolving power R ~ 2750. It also has a low resolution prism mode with a resolving power R ~ 100-350 for high throughput observations. Built-in slit viewer also provides a 1 x 1 arcmin2 Field-of-View (FoV) imaging in r', i', Y, J, H, Ks broad-band filters & H2 and BrG narrow-band filters. TANSPEC will be used for a wide range of studies from local star formation to extra-galactic astronomy.

D.K. Ojha1, S.K. Ghosh1, J.P. Ninan2, P. Manoj1, S.L.A. D'Costa1, M.B. Naik1, S.S. Poojary1, P.R. Sandimani1, H. Shah1, S.B. Bhagat1,

R.B. Jadhav1, S.M. Gharat1, G.S. Meshram1, C.B. Bakalkar1, B.G. Bagade1, S. Sharma3, A.K. Pandey3 , B. Kumar3

ojha@tifr.res.in 1TIFR (Mumbai, India), 2Penn State University (USA) , 3ARIES (Nainital, India)

TANSPEC Specifications: Site: 3.6-m DOT, Devasthal, Nainital, India. Wavelength coverage: 0.6-2.54 microns. Broad-band: r’, i’, Y, J, H, Ks; Narrow-band: H2 and BrG. Field of View (FoV): 1 x 1 arcmin2

Spectral Resolution:~2750 (XD mode) and ~ 100-350 (prism mode). Built in collaboration with MKIR, HAWAII. Expected First light: First quarter of 2019 . Will be utilized for star formation and extra-galactic astronomy studies

Calibration Unit Using uniform flat field from an integrating sphere outside the dewar as an identical f/9 beam from telescope. Wavelength calibration:Argon & Neon lamps Flat Calibration: 10 Watts Quartz Tungsten Halogen (QTH) lamp and 0.1 Watt bulb.

Optical Layout of the TANSPEC

GUI for instrument control

Unique capability of simultaneous coverage from optical to NIR

Prism Mode

The assembly of the cryostat and all of the mechanisms

TANSPEC Operations and Current Status: Assembly of cryostat and all the mechanisms have been completed. Installation and alignment of optics and Near Infrared (NIR) detectors have been

completed. Array readout software has been tested using MUX and NIR detectors. Final cold run using all the mechanical & optical components and NIR detector has

been successfully done. Spectra in the lab have been analyzed and it matches the optical simulations. TANSPEC is under shipment to India and it will be commissioned at the Devasthal

Optical Telescope (DOT) observatory, during the first quarter of 2019.

First observed spectrum using Neon lamp with optical model overlaid

Future Plan: TANSPEC is under shipment to DOT. It will be installed and tested in the first quarter of 2019.

XD mode Prism Mode

Modes of operation Spectrograph operates in two modes. The spectrum is imaged on a 2K x 2K H2RG array. Prism mode : High throughput mode, low resolving power. XD Mode: High spectral resolution, combination of a grating and two prisms.

Dispersion Maps

TANSPEC 3.6-m ARIES Devasthal Optical Telescope (DOT)

Slit Viewer/Imager Consists of an independent imaging camera with a 1k x 1k H1RG detector. Reflected beam from slit mirror is imaged to the camera through filter wheel. Camera has a field of view of 1 x 1 arcmin2 and is used for guiding the telescope (IR guider) as well as for photometry.

Low resolution mode saturated at the K end

Optics Offner relay foreoptics. f/9 beam from the telescope reimaged as f/12 beam on the slit. Secondary of the telescope is imaged to the secondary of offner working as cold stop to block stray light. Integrated calibration unit.

DAIM -2019

XD Mode