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Joint Survey Processing II: Stellar Proper Motions in the COSMOS Field, from Hubble Space Telescope ACS and Subaru Telescope HSC Observations

Fajardo-Acosta, Sergio B. and Faisst, Andreas and Grillmair, Carl J. and Chary, Ranga-Ram and Paladini, Roberta and Rusholme, Ben and Stickley, Nathaniel (2022) Joint Survey Processing II: Stellar Proper Motions in the COSMOS Field, from Hubble Space Telescope ACS and Subaru Telescope HSC Observations. . (Unpublished)

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We analyze stellar proper motions in the COSMOS field to assess the presence of bulk motions. At bright magnitudes (G-band 18.5-20.76 AB), we use the proper motions of 1,010 stars in the Gaia DR2 catalog. At the faint end, we computed proper motions of 11,519 point-like objects at i-band magnitudes 19-25 AB using Hubble ACS and Subaru HSC, which span two epochs about 11 years apart. In order to measure these proper motions with unprecedented accuracy at faint magnitudes, we developed a foundational set of astrometric tools which will be required for Joint Survey Processing (JSP) of data from the next generation of optical/infrared surveys. The astrometric grids of Hubble ACS and Subaru HSC mosaics were corrected at the catalog level, using proper motion-propagated and parallax-corrected Gaia DR2 sources. These astrometric corrections were verified using compact extragalactic sources. Upon comparison of our measured proper motions with Gaia DR2, we estimate the uncertainties in our measurements to be ~2--3 mas/yr per axis, down to 25.5 AB mag. We corrected proper motions for the mean motion of the Sun, and we find that late-type main-sequence stars predominantly in the thin disk in the COSMOS field have space velocities mainly towards the Galactic center. We detect candidate high-velocity (> 220 km/s) stars, 6 of them at ~0.4-6 kpc from the Gaia sample, and 5 of them at ~20 kpc from the faint star HSC and ACS sample. The sources from the faint star sample may be candidate halo members of the Sangarius stream.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Fajardo-Acosta, Sergio B.0000-0001-9309-0102
Faisst, Andreas0000-0002-9382-9832
Grillmair, Carl J.0000-0003-4072-169X
Chary, Ranga-Ram0000-0001-7583-0621
Paladini, Roberta0000-0002-5158-243X
Rusholme, Ben0000-0001-7648-4142
Stickley, Nathaniel0000-0003-0987-5738
Additional Information:Received 2021 Nov 20; Revised 2022 Feb 24; Accepted 2022 Mar 1, ApJ, in press. We thank Dr. Davy Kirkpatrick for very insightful discussions, and the anonymous referee for very helpful suggestions. The Hyper Suprime-Cam (HSC) collaboration includes the astronomical communities of Japan and Taiwan, and Princeton University. The HSC instrumentation and software were developed by the National Astronomical Observatory of Japan (NAOJ), the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), the University of Tokyo, the High Energy Accelerator Research Organization (KEK), the Academia Sinica Institute for Astronomy and Astrophysics in Taiwan (ASIAA), and Princeton University. Funding was contributed by the FIRST program from Japanese Cabinet Office, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), the Japan Society for the Promotion of Science (JSPS),Japan Science and Technology Agency (JST), the Toray Science Foundation, NAOJ, Kavli IPMU, KEK, ASIAA, and Princeton University. This paper makes use of software developed for the Large Synoptic Survey Telescope. We thank the LSST Project for making their code available as free software at Based in part on data collected at the Subaru Telescope and retrieved from the HSC data archive system, which is operated by Subaru Telescope and Astronomy Data Center at National Astronomical Observatory of Japan. This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Facilities: HST(ACS), Subaru(HSC), Gaia Software: SExtractor (Bertin & Arnouts 1996)
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Cabinet Office (Japan)UNSPECIFIED
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Japan Society for the Promotion of Science (JSPS)UNSPECIFIED
Japan Science and Technology AgencyUNSPECIFIED
Toray Science FoundationUNSPECIFIED
National Astronomical Observatory of JapanUNSPECIFIED
Kavli Institute for the Physics and Mathematics of the UniverseUNSPECIFIED
High Energy Accelerator Research Organization (KEK)UNSPECIFIED
Academia Sinica Institute for Astronomy and AstrophysicsUNSPECIFIED
Princeton UniversityUNSPECIFIED
Gaia Multilateral AgreementUNSPECIFIED
Department of Energy (DOE)DE-AC02-05CH11231
Subject Keywords:stars: proper motion - stars - catalogs - Galaxy: structure
Record Number:CaltechAUTHORS:20220504-215450097
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114593
Deposited By: Tony Diaz
Deposited On:04 May 2022 23:50
Last Modified:04 May 2022 23:50

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