Analyzing the Atmospheric Dispersion Correction of the Gemini Planet Imager: residual dispersion above design requirements
Abstract: The Atmospheric Dispersion Corrector (ADC) of the Gemini Planet Imager (GPI) corrects the chromatic dispersion caused by differential atmospheric refraction (DAR), making it an important optic for exoplanet observation. Despite requiring less than 5 mas of residual DAR to avoid potentially affecting the coronagraph, the GPI ADC averages $\sim7$ and $\sim11$ mas of residual DAR in $H$ and $J$ band respectively. We analyzed GPI data in those bands to find explanations for the underperformance. We found the model GPI uses to predict DAR underestimates humidity's impact on incident DAR, causing on average a 0.54 mas increase in $H$ band residual DAR. Additionally, the GPI ADC consistently undercorrects in $H$ band by about 7 mas, causing almost all the $H$ band residual DAR. $J$ band does not have such an offset. Perpendicular dispersion induced by the GPI ADC, potentially from a misalignment in the prisms' relative orientation, causes 86% of the residual DAR in $J$ band. Correcting these issues could reduce residual DAR, thereby improving exoplanet detection. We also made a new approximation for the index of refraction of air from 0.7 microns to 1.36 microns that more accurately accounts for the effects of humidity.
- H. G. Roe, “Implications of Atmospheric Differential Refraction for Adaptive Optics Observations,” Publications of the Astronomical Society of the Pacific 114, 450–461 (2002).
- B. Macintosh, J. R. Graham, P. Ingraham, et al., “First light of the Gemini Planet Imager,” Proceedings of the National Academy of Science 111, 12661–12666 (2014).
- P. Hibon, S. Thomas, J. Dunn, et al., “Characterization of the atmospheric dispersion corrector of the Gemini planet imager,” in Ground-based and Airborne Instrumentation for Astronomy V, S. K. Ramsay, I. S. McLean, and H. Takami, Eds., Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series 9147, 91474U (2014).
- R. J. Mathar, “Refractive index of humid air in the infrared: model fits,” Journal of Optics A: Pure and Applied Optics 9, 470–476 (2007).
- J. A. van den Born and W. Jellema, “Quantification of the expected residual dispersion of the MICADO Near-IR imaging instrument,” Monthly Notices of the Royal Astronomical Society 496, 4266–4275 (2020).
- E. L. Nielsen, R. J. De Rosa, B. Macintosh, et al., “The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics from 10 to 100 au,” Astronomical Journal 158, 13 (2019).
- M. D. Perrin, J. Maire, P. Ingraham, et al., “Gemini Planet Imager observational calibrations I: Overview of the GPI data reduction pipeline,” in Ground-based and Airborne Instrumentation for Astronomy V, S. K. Ramsay, I. S. McLean, and H. Takami, Eds., Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series 9147, 91473J (2014).
- M. D. Perrin, P. Ingraham, K. B. Follette, et al., “Gemini Planet Imager observational calibrations XI: pipeline improvements and enhanced calibrations after two years on sky,” in Ground-based and Airborne Instrumentation for Astronomy VI, C. J. Evans, L. Simard, and H. Takami, Eds., Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series 9908, 990837 (2016).
- J. J. Wang, M. D. Perrin, D. Savransky, et al., “Automated data processing architecture for the Gemini Planet Imager Exoplanet Survey,” Journal of Astronomical Telescopes, Instruments, and Systems 4, 018002 (2018).
- Q. M. Konopacky, S. J. Thomas, B. A. Macintosh, et al., “Gemini planet imager observational calibrations V: astrometry and distortion,” in Ground-based and Airborne Instrumentation for Astronomy V, S. K. Ramsay, I. S. McLean, and H. Takami, Eds., Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series 9147, 914784 (2014).
- C. Marois, D. Lafrenière, B. Macintosh, et al., “Accurate Astrometry and Photometry of Saturated and Coronagraphic Point Spread Functions,” Astrophysical Journal 647, 612–619 (2006).
- A. Sivaramakrishnan and B. R. Oppenheimer, “Astrometry and Photometry with Coronagraphs,” Astrophysical Journal 647, 620–629 (2006).
- J. J. Wang, A. Rajan, J. R. Graham, et al., “Gemini planet imager observational calibrations VIII: characterization and role of satellite spots,” in Ground-based and Airborne Instrumentation for Astronomy V, S. K. Ramsay, I. S. McLean, and H. Takami, Eds., Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series 9147, 914755 (2014).
- R. J. De Rosa, M. M. Nguyen, J. Chilcote, et al., “Revised astrometric calibration of the Gemini Planet Imager,” Journal of Astronomical Telescopes, Instruments, and Systems 6, 015006 (2020).
- J. Chilcote, Q. Konopacky, R. J. De Rosa, et al., “GPI 2.0: upgrading the Gemini Planet Imager,” in Ground-based and Airborne Instrumentation for Astronomy VIII, C. J. Evans, J. J. Bryant, and K. Motohara, Eds., Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series 11447, 114471S (2020).
- J. J. Wang, J. K. Wallace, N. Jovanovic, et al., “An atmospheric dispersion corrector design with milliarcsecond-level precision from 1 to 4 microns for high dispersion coronagraphy,” in Ground-based and Airborne Instrumentation for Astronomy VIII, C. J. Evans, J. J. Bryant, and K. Motohara, Eds., Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series 11447, 1144754 (2020).
- C. Y. Hohenkerk and A. T. Sinclair, “The Computation of an Angular Atmospheric Refraction at Large Zenith Angles,” NAO Technical note , 315–316 (1985).
- G. Bönsch and E. Potulski, “Measurement of the refractive index of air and comparison with modified Edlén’s formulae,” Metrologia 35, 133 (1998).
- J. C. Owens, “Optical refractive index of air: dependence on pressure, temperature, and composition,” Applied Optics 6, 51 (1967).
- B. Edlén, “The Refractive Index of Air,” Metrologia 2, 71–80 (1966).
- B. Edlén, “The dispersion of standard air,” Journal of the Optical Society of America (1917-1983) 43, 339 (1953).
- P. E. Ciddor, “Refractive index of air: new equations for the visible and near infrared,” Applied Optics 35, 1566 (1996).
- H. Barrell and J. E. Sears, “The Refraction and Dispersion of Air for the Visible Spectrum,” Philosophical Transactions of the Royal Society of London Series A 238, 1–64 (1939).
- Astropy Collaboration, T. P. Robitaille, E. J. Tollerud, et al., “Astropy: A community Python package for astronomy,” Astronomy & Astrophysics 558, A33 (2013).
- Astropy Collaboration, A. M. Price-Whelan, B. M. Sipőcz, et al., “The Astropy Project: Building an Open-science Project and Status of the v2.0 Core Package,” Astronomical Journal 156, 123 (2018).
Paper Prompts
Sign up for free to create and run prompts on this paper using GPT-5.
Top Community Prompts
Collections
Sign up for free to add this paper to one or more collections.