TIFR Near Infrared Imaging Camera-II on the 3.6 m Devasthal Optical Telescope

Tata Institute of Fundamental Research (TIFR) Near Infrared Imaging Camera-II (TIRCAM2) is a closed-cycle Helium cryo-cooled imaging camera equipped with a Raytheon 512 x 512 pixels InSb Aladdin III Quadrant focal plane array (FPA) having sensitivity to photons in the 1-5 mu m wavelength band. In this paper, we present the performance of the camera on the newly installed 3.6m Devasthal Optical Telescope (DOT) based on the calibration observations carried out during 2017 May 11-14 and 2017 October 7-31. After the preliminary characterization, the camera has been released to the Indian and Belgian astronomical community for science observations since 2017 May. The camera offers a field-of-view (FoV) of similar to 86.5 " x 86.5 " on the DOT with a pixel scale of 0.169 ". The seeing at the telescope site in the near-infrared (NIR) bands is typically sub-arcsecond with the best seeing of similar to 0.45 " realized in the NIR K-band on 2017 October 16. The camera is found to be capable of deep observations in the J, H and K bands comparable to other 4m class telescopes available world-wide. Another highlight of this camera is the observational capability for sources up to Wide-field Infrared Survey Explorer (WISE) W1-band (3.4 mu m) magnitudes of 9.2 in the narrow L-band (nbL; lambda(cen) similar to 3.59 mu m). Hence, the camera could be a good complementary instrument to observe the bright nbL-band sources that are saturated in the Spitzer-Infrared Array Camera (IRAC) ([3.6] less than or similar to 7.92 mag) and the WISE W1-band ([3.4] less than or similar to 8.1 mag). Sources with strong polycyclic aromatic hydrocarbon (PAH) emission at 3.3 mu m are also detected. Details of the observations and estimated parameters are presented in this paper.