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arXiv · 1902.05857

First-light images from low dispersion spectrograph-cum-imager on 3.6-meter Devasthal Optical Telescope

Amitesh Omar·T. S. Kumar·B. Krishna Reddy·Jayshreekar Pant·Manoj Mahto
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Abstract

A low dispersion spectrograph-cum-imager has been developed and assembled in ARIES, Nainital. The optical design of the spectrograph consists of a collimator and a focal reducer converting the f/9 beam from the 3.6-m Devasthal optical telescope to a nearly f/4.3 beam. The instrument is capable of carrying out broad-band imaging, narrow-band imaging and low-resolution ({\lambda}/{\Delta}{\lambda}<2000) slit spectroscopy in the wavelength range 350-1050 nm. A closed-cycle cryogenically cooled charge-coupled device camera, also assembled in ARIES, is used as the main imaging device for the spectrograph. The first images from the spectrograph on the telescope assert seeing-limited performance free from any significant optical aberration. An i-band image of the galaxy cluster Abell 370 made using the spectrograph shows faint sources down to ~25 mag. The quality and sensitivity of the optical spectrums of the celestial sources obtained from the spectrograph are as per the expectations from a 3.6-m telescope. Several new modes of observations such as polarimetry, fast-imaging, and monitoring of the atmospheric parameters are being included in the spectrograph. Using a test setup, single optical pulses from the Crab pulsar were detected from the telescope. The spectrograph is one of the main back-end instruments on the 3.6-m telescope for high sensitivity observations of celestial objects.

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Amitesh Omar, T. S. Kumar, B. Krishna Reddy, Jayshreekar Pant, Manoj Mahto. 2019-02-15. First-light images from low dispersion spectrograph-cum-imager on 3.6-meter Devasthal Optical Telescope. https://doi.org/10.18520/cs%2Fv116%2Fi9%2F1472-1478

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