A New Method to Reduce Near-Infrared Data of Palomar Observatory

Abstract

Compared to large optical spectral surveys, near infrared spectra is overwhelmingly outnumbered. Sloan Digital Sky Survey (SDSS), the largest optical spectroscopic survey, has published about 5,789,200 optical spectra in its latest data release DR16, while no large scale near infrared spectra survey has been performed. Typical studies in near infrared are based on limited samples of a few tens to hundreds of near infrared spectra. TripleSpec is one of the workhorses near Infrared (NIR) spectrograph, mounted on the Palomar 200-inch telescope (P200). We have acquired more than 200 new quasar NIR spectra during the past years, compared to the largest sample ever compiled. During the reduction of our latest TripleSpec data, we found that the well accepted data reduction pipeline Spextool (citation: 835) completely ignored one of the five spectral orders (Order 7) of the raw data, probably due to its low throughput. Astronomical observations are always photons starving, we investigate the possibility of incorporation of the photons on Order 7 by developing a new data reduction pipeline. We test the new pipeline on our new quasar NIR data. Compared to the results from Spextool, 1. The pipeline is also featured by its full automaticity, 2. the wavelength coverage extended from 1-2.5 μm to 0.9-2.5 μm, revealing new features such as rest frame Pa ε, [S III] 9531, [C I] 9824, [C I] 9850, [S VIII] 9910, as well as redshifted spectral features for higher redshift targets. 3. The median signal to noise ratio for 0.9-1.1 μm have been elevated by a factor of 2. The pipeline could be easily generalized to accommodate other popular NIR instruments such as IRTF/SPEX, we plan to publish the pipeline and the 200 new quasar NIR spectra to the community. Keck/NIRSPEC.