Comprehensive data reduction package for the Immersion GRating INfrared Spectrograph: IGRINS Chae Kyung Sim a , Huynh Anh Nguyen Le a , Soojong Pak a,⇑ , Hye-In Lee a , Wonseok Kang b , Moo-Young Chun c , Ueejeong Jeong c , In-Soo Yuk c , Kang-Min Kim c , Chan Park c , Michael D. Pavel d , Daniel T. Jaffe a,d a Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 446-701, Republic of Korea b National Youth Space Center, 200 Deokheungyangjjok-gil, Dongil-myeon, Goheung-gun, Jeollanam-do 548-951, Republic of Korea c Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 305-348, Republic of Korea d University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712, USA Received 13 January 2014; received in revised form 28 February 2014; accepted 28 February 2014 Available online 10 March 2014 Abstract We present a Python-based data reduction pipeline package (PLP) for the Immersion GRating INfrared Spectrograph (IGRINS), an instrument that covers the complete H- and K-bands in one exposure with a spectral resolving power of 40,000. The reduction steps carried out by the PLP include flat-fielding, background removal, order extraction, distortion correction, wavelength calibration, and telluric correction using spectra of A type standard stars. As the spectrograph has no moving parts, the PLP automatically reduces the data using predefined functions for the processes of order extraction, distortion correction, and wavelength calibration. Before the telluric correction of the target spectra, the intrinsic hydrogen absorption features of the standard A star are removed with a Gauss- ian fitting algorithm. The final result is the flux of the target as a function of wavelength. Users can customize the predefined functions for the extraction of the spectrum from the echellogram and adjust the parameters for the fitting functions for the spectra of celestial objects, using “fine-tuning” options, as necessary. Presently, the PLP produces the best results for point-source targets. Ó 2014 COSPAR. Published by Elsevier Ltd. All rights reserved. Keywords: Methods: data analysis; Techniques: spectroscopic 1. Introduction IGRINS (Immersion GRating INfrared Spectrograph) is a cross-dispersed near-infrared spectrograph that uses a silicon immersion echelle grating as its main dispersing element. It covers all of the H- and K-bands in a single exposure with a resolving power of R ¼ k=Dk  40; 000. The H- and K-bands echellograms consist of 23 and 20 orders, respectively (Fig. 1). Since the spectrograph has no moving parts, the transformation functions for the order extraction, distortion correction, and wavelength cal- ibration vary very little from one exposure to the next. Hence, a deliberately designed pipeline is to provide stable quality of data reduction process with minimal human intervention. The full IGRINS hardware and software system is described earlier (Yuk et al., 2010). The IGRINS software consists of six packages to be used before, in the middle of, and after the observation. To prepare the observation, one can use the Exposure Time Calulator (ETC) and a finding- chart produced with the Observational Preparation Pack- age (OPP). During the observation, Housekeeping Package http://dx.doi.org/10.1016/j.asr.2014.02.024 0273-1177/Ó 2014 COSPAR. Published by Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: cksim@khu.ac.kr (C.K. Sim), soojong@khu.ac.kr (S. Pak). www.elsevier.com/locate/asr Available online at www.sciencedirect.com ScienceDirect Advances in Space Research 53 (2014) 1647–1656