NICSPol: A near-infrared polarimeter for the 1.2-m telescope at Mount Abu Infrared Observatory

Near infrared camera spectrograph and polarimeter (NICSPol) is a near-infrared (NIR) imaging polarimeter developed for the Near-Infrared Camera and Spectrograph (NICS), one of the backend instruments of the 1.2-m Cassegrain telescope at the Mount Abu Infrared Observatory, India. The polarimeter consists of a rotating wire grid polarizer, which is mounted between the telescope optics and the NICS. The polarimetric observations are carried out by rotating the polarizer using a motorized mechanism to determine the Stokes parameters, which are then converted into the polarization fraction and polarization angle. We report the details of the instrument and the results of observations of infrared polarimetric standards. A set of polarized and unpolarized standards were observed using NICSPol over J, H, and Ks bands covering 0.8 to 2.5 μm. The observations of polarized standards using NICSPol show that NICSPol can constrain polarization within ∼1 % for sources brighter than ∼16 magnitude in J, H, and Ks bands. NICSPol is a general purpose instrument that could be used to study variety of astrophysical sources such as AGNs, pulsars, XRBs, supernovae, and star-forming regions. With few NIR polarimeters available worldwide so far, NICSPol would be the first imaging NIR polarimeter in India.