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Published June 2020 | Published + Submitted
Journal Article Open

HD 165054: An Astrometric Calibration Field for High-contrast Imagers in Baade's Window

Abstract

We present a study of the HD 165054 astrometric calibration field that has been periodically observed with the Gemini Planet Imager (GPI). HD 165054 is a bright star within Baade's Window, a region of the galactic plane with relatively low extinction from interstellar dust. HD 165054 was selected as a calibrator target due to the high number density of stars within this region (~3 stars per square arcsecond with H < 22), necessary because of the small field of view of the GPI. Using nine epochs spanning over five years, we have fit a standard five-parameter astrometric model to the astrometry of seven background stars within close proximity to HD 165054 (ρ < 2''). We achieved a proper motion precision of ~0.3 mas yr⁻¹ and constrained the parallax of each star to be ≾1 mas. Our measured proper motions and parallax limits are consistent with the background stars being a part of the galactic bulge. Using these measurements, we find no evidence of any systematic trend of either the plate scale or the north angle offset of GPI between 2014 and 2019. We compared our model describing the motions of the seven background stars to observations of the same field in 2014 and 2018 obtained with Keck/NIRC2, an instrument with excellent astrometric calibration. We find that the predicted position of the background sources is consistent with that measured by NIRC2, within the uncertainties of the calibration of the two instruments. In the future, we will use this field as a standard astrometric calibrator for the upgrade of GPI and potentially for other high-contrast imagers.

Additional Information

© 2020 The American Astronomical Society. Received 2019 October 25; revised 2020 March 30; accepted 2020 April 2; published 2020 May 1. This work is based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), under a cooperative agreement with the National Science Foundation (NSF) on behalf of the Gemini partnership: the NSF (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil). Some of the data presented herein were obtained at the W. M. Keck Observatory, which was made possible by the generous financial support of the W. M. Keck Foundation and is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. This work has also made use of data from the European Space Agency mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This research has made use of the SIMBAD database and the VizieR catalog access tool, both operated at the CDS, Strasbourg, France. This research has made use of the Washington Double Star Catalog maintained at the U.S. Naval Observatory. Supported by NSF grants AST-1411868 (E.L.N., K.B.F., B.M., and J.P.), AST-141378 (G.D.), and AST-1518332 (M.M.N., R.J.D.R., T.M.E., J.R.G., P.K., G.D.). Supported by NASA grants NNX14AJ80G (E.L.N., B.M., F.M., and M.P.), NNX15AC89G and NNX15AD95G/NExSS (M.M.N., R.J.D.R., B.M., T.M.E., J.J.W., G.D., J.R.G., P.K.), and NN15AB52l (D.S.). M.M.B. was supported by NASA through Hubble Fellowship grant #51378.01-A, awarded by the Space Telescope Science Institute, which is operated by AURA, for NASA, under contract NAS5-26555. K.W.D. is supported by an NRAO Student Observing Support Award SOSPA3-007. J.J.W. is supported by the Heising-Simons Foundation 51 Pegasi b postdoctoral fellowship. This work benefited from NASA's Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA's Science Mission Directorate. Software: Gemini Planet Imager Data Pipeline (Perrin et al. 2014, 2016, http://ascl.net/1411.018), pyKLIP (Wang et al. 2015, http://ascl.net/1506.001), emcee (Foreman-Mackey et al. 2013, http://ascl.net/1303.002), Astropy (The Astropy Collaboration et al. 2013). Facilities: Gemini:South - Gemini South Telescope, Keck:II (NIRC2). -

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Published - Nguyen_2020_AJ_159_244.pdf

Submitted - 2004.02923.pdf

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Created:
August 22, 2023
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