Development of ProtoPol: a medium-resolution echelle spectro-polarimeter for PRL telescopes, Mt. Abu, India—Part II: the data-reduction pipeline, on-sky characterization and performance verification, and first science results

We present the development of ProtoPol—a medium-resolution echelle spectro-polarimeter for the PRL 1.2 and 2.5 m telescopes at Mt. Abu observatory, India. In this second and final part of the paper series, we report on the development of a dedicated data reduction pipeline of ProtoPol along with several characterization, performance evaluation, and scientific observations to quantify the performance of the instrument. ProtoPol provides a spectral resolution in the range of ∼0.4 to 0.75 Å across various orders in the visible wavelength range of 4000 to 9600 Å. On PRL 2.5 m telescope, a signal-to-noise ratio of 10 is achieved for mV∼13.2 source in 1 h of integration time, and its throughput is estimated to be ∼6%, including all the contributing factors such as atmospheric transmission, telescope reflectivity, the instrument’s optics, and CCD efficiency. ProtoPol achieved a linear polarization accuracy δP≈0.1 to 0.2% in 2 h of integration time for a source with mV≈8. The instrumental polarization is determined to be around 0.1%. We also present the first science results with ProtoPol to demonstrate the capabilities of the instrument. Samples of Herbig Ae/Be stars, classical Be stars, symbiotic stars, and AGB/post-AGB stars were observed over the period of one and half years for their spectro-polarimetry measurements covering various physical mechanisms such as intrinsic line polarization in Herbig and classical Be stars, Raman scattered features in symbiotic stars, and continuum polarization in AGB/post-AGB stars to verify the polarization performance of the instrument.