Observations with the 3.6-meter Devasthal optical telescope
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J. Astrophys. Astr. (2020) 41:33 https://doi.org/10.1007/s12036-020-09652-9
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Observations with the 3.6-meter Devasthal optical telescope RAM SAGAR1,2,* , BRIJESH KUMAR2 and SAURABH SHARMA2 1
Indian Institute of Astrophysics, Sarjapur Road, Koramangala, Bengaluru 560 034, India. Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263 001, India. E-mail: [email protected] 2
MS received 20 August 2020; accepted 5 October 2020 Abstract. The 3.6-meter Indo–Belgian Devasthal optical telescope (DOT) has been used for optical and nearinfrared (NIR) observations of celestial objects. The telescope has detected stars of B ¼ 24:5 0:2; R ¼ 24:6 0:12 and g ¼ 25:2 0:2 mag in exposure times of 1200, 4320 and 3600 s 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 ¼ 20 0:1; H ¼ 18:8 0:1 and K ¼ 18:2 0:1 mag can be detected in effective exposure times of 500, 550 and 1000 s 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 with angular separation of 0:00 4 has been resolved by the telescope. Sky images with sub-arcsec 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. Owing to the advantage of its geographical location, the 3.6-meter DOT can provide optical and NIR observations for a number of frontline galactic and extra-galactic astrophysical research problems, including optical follow-up of GMRT and AstroSat sources and optical transient objects. Keywords. Optical telescope—Sky performance—Detection limits at optical and near-infrared wavelengths.
1. Introduction Devasthal (meaning abode of God) is a mountain peak (longitude 79.° 7 E, latitude 29.° 4 N, and altitude 2424 ± 4 m). It is located at a distance of 55 km by road from Nainital in Kumaon region of central Himalaya. Figure 1 shows an aerial view of the Devasthal observatory and a topographic contour map of the region. The location was identified after decades of detailed site survey using modern instruments (Sagar 2000; Stalin 2001 and references therein). After successful installation and technical checks the 3.6-meter Indo–Belgian Devasthal optical telescope (DOT) was activated by the prime ministers of India
This article is part of the Topical Collection: Chemical elements in the Universe: Origin and evolution.
and Belgium from Brussels on March 30, 2016, and since then it is in use for training people, testing backend instruments, and making observations of various types of celestial objects. A description of the actively supported and modern DOT is given in the next se
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