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Time-series and Phase-curve Photometry of the Episodically Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200, and ZTF

Purdum, Josiah N. and Lin, Zhong-Yi and Bolin, Bryce T. and Sharma, Kritti and Choi, Philip I. and Bhalerao, Varun and Hanuš, Josef and Kumar, Harsh and Quimby, Robert and van Roestel, Joannes C. and Zhai, Chengxing and Fernandez, Yanga R. and Lisse, Carey M. and Bodewits, Dennis and Fremling, Christoffer and Ryan Golovich, Nathan and Hsu, Chen-Yen and Ip, Wing-Huen and Ngeow, Chow-Choong and Saini, Navtej S. and Shao, Michael and Yao, Yuhan and Ahumada, Tomás and Anand, Shreya and Andreoni, Igor and Burdge, Kevin B. and Burruss, Rick and Chang, Chan-Kao and Copperwheat, Chris M. and Coughlin, Michael and De, Kishalay and Dekany, Richard and Delacroix, Alexandre and Drake, Andrew and Duev, Dmitry and Graham, Matthew and Hale, David and Kool, Erik C. and Kasliwal, Mansi M. and Kostadinova, Iva S. and Kulkarni, Shrinivas R. and Laher, Russ R. and Mahabal, Ashish and Masci, Frank J. and Mróz, Przemyslaw J. and Neill, James D. and Riddle, Reed and Rodriguez, Hector and Smith, Roger M. and Walters, Richard and Yan, Lin and Zolkower, Jeffry (2021) Time-series and Phase-curve Photometry of the Episodically Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200, and ZTF. Astrophysical Journal Letters, 911 (2). Art. No. L35. ISSN 2041-8205. doi:10.3847/2041-8213/abf2ca.

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We observed the episodically active asteroid (6478) Gault in 2020 with multiple telescopes in Asia and North America and found that it is no longer active after its recent outbursts at the end of 2018 and the start of 2019. The inactivity during this apparition allowed us to measure the absolute magnitude of Gault of H_r = 14.63 ± 0.02, G_r = 0.21 ± 0.02 from our secular phase-curve observations. In addition, we were able to constrain Gault's rotation period using time-series photometric lightcurves taken over 17 hr on multiple days in 2020 August, September, and October. The photometric lightcurves have a repeating ≾0.05 mag feature suggesting that (6478) Gault has a rotation period of ~2.5 hr and may have a semispherical or top-like shape, much like the near-Earth asteroids Ryugu and Bennu. The rotation period of ~2.5 hr is near the expected critical rotation period for an asteroid with the physical properties of (6478) Gault, suggesting that its activity observed over multiple epochs is due to surface mass shedding from its fast rotation spin-up by the Yarkovsky–O'Keefe–Radzievskii–Paddack effect.

Item Type:Article
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URLURL TypeDescription Paper
Purdum, Josiah N.0000-0003-1227-3738
Lin, Zhong-Yi0000-0003-3827-8991
Bolin, Bryce T.0000-0002-4950-6323
Sharma, Kritti0000-0002-4477-3625
Bhalerao, Varun0000-0002-6112-7609
Hanuš, Josef0000-0002-2934-3723
Kumar, Harsh0000-0003-0871-4641
Quimby, Robert0000-0001-9171-5236
van Roestel, Joannes C.0000-0002-2626-2872
Zhai, Chengxing0000-0002-0291-4522
Fernandez, Yanga R.0000-0003-1156-9721
Lisse, Carey M.0000-0002-9548-1526
Bodewits, Dennis0000-0002-2668-7248
Fremling, Christoffer0000-0002-4223-103X
Ryan Golovich, Nathan0000-0003-2632-572X
Hsu, Chen-Yen0000-0002-8390-3082
Ip, Wing-Huen0000-0002-3140-5014
Ngeow, Chow-Choong0000-0001-8771-7554
Yao, Yuhan0000-0001-6747-8509
Ahumada, Tomás0000-0002-2184-6430
Anand, Shreya0000-0003-3768-7515
Andreoni, Igor0000-0002-8977-1498
Burdge, Kevin B.0000-0002-7226-836X
Chang, Chan-Kao0000-0003-1656-4540
Copperwheat, Chris M.0000-0001-7983-8698
Coughlin, Michael0000-0002-8262-2924
De, Kishalay0000-0002-8989-0542
Dekany, Richard0000-0002-5884-7867
Duev, Dmitry0000-0001-5060-8733
Graham, Matthew0000-0002-3168-0139
Kool, Erik C.0000-0002-7252-3877
Kasliwal, Mansi M.0000-0002-5619-4938
Kulkarni, Shrinivas R.0000-0001-5390-8563
Laher, Russ R.0000-0003-2451-5482
Mahabal, Ashish0000-0003-2242-0244
Masci, Frank J.0000-0002-8532-9395
Mróz, Przemyslaw J.0000-0001-7016-1692
Neill, James D.0000-0002-0466-1119
Riddle, Reed0000-0002-0387-370X
Smith, Roger M.0000-0001-7062-9726
Walters, Richard0000-0002-1835-6078
Yan, Lin0000-0003-1710-9339
Alternate Title:Time-series and Phasecurve Photometry of Episodically-Active Asteroid (6478) Gault in a Quiescent State Using APO, GROWTH, P200 and ZTF
Additional Information:© 2021. The American Astronomical Society. Received 2021 February 20; revised 2021 March 17; accepted 2021 March 26; published 2021 April 26. Based on observations obtained with the Samuel Oschin Telescope 48 inch and the 60 inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under grant No. AST-2034437 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, and IN2P3, France. Operations are conducted by COO, IPAC, and UW. This work was supported by the GROWTH project funded by the National Science Foundation under PIRE grant No. 1545949. Part of this work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. B.T.B. and F.J.M. acknowledge support from NASA with grant No. 80NSSC19K0780. C.F. gratefully acknowledges the support of his research by the Heising-Simons Foundation (# 2018-0907). M.C. acknowledges support from the National Science Foundation with grant No. PHY-2010970. This publication has made use of data collected at Lulin Observatory, partly supported by MoST grant 108-2112-M-008-001. C.C.N. thanks the funding from MOST grant 104-2923-M-008-004-MY5. C.Z. acknowledges support from JPL's internal research funds of the R&TD, JROC, and ESD HBCU/MSI programs. J.N.P. and R.Q. acknowledge support from JPL's ESD HBCU/MSI program under subcontract 1659249. The work of J.H. has been supported by the Czech Science Foundation through grant 20-08218S and by the Charles University Research program No. UNCE/SCI/023. V.B., K.S., and H.K. thank Kunal Deshmukh for help with data processing. The GROWTH-India telescope is a 70 cm telescope with a 0.7 degree field of view, set up by the Indian Institute of Astrophysics and the Indian Institute of Technology Bombay with support from the Indo-US Science and Technology Forum (IUSSTF) and the Science and Engineering Research Board (SERB) of the Department of Science and Technology (DST), Government of India ( It is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA). The GROWTH-India project is supported by SERB and administered by IUSSTF. H.K. thanks the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining grant #1829740, the Brinson Foundation, and the Moore Foundation; his participation in the program has benefited this work. Facilities: Apache Point Astrophysical Research Consortium 3.5 m telescope - , GROWTH-India Telescope - , Lulin Optical Telescope - , Mount Laguna Observatory 40 inch Telescope - , P48 Oschin Schmidt telescope/Zwicky Transient Facility - , Table Mountain Observatory. - Software: Astropy (Astropy Collaboration et al. 2013, 2018), ZChecker (Kelley et al. 2019), Aperture Photometry Tool (Laher et al. 2012).
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility
Funding AgencyGrant Number
ZTF partner institutionsUNSPECIFIED
Department of Energy (DOE)DE-AC52-07NA27344
Heising-Simons Foundation2018-0907
Ministry of Science and Technology (Taipei)108-2112-M-008-001
Ministry of Science and Technology (Taipei)104-2923-M-008-004-MY5
JPL Research and Technology Development FundUNSPECIFIED
Czech Science Foundation20-08218S
Charles UniversityUNCE/SCI/023
Indo-US Science and Technology ForumUNSPECIFIED
Science and Engineering Research Board (SERB)UNSPECIFIED
Large Synoptic Survey Telescope CorporationUNSPECIFIED
Brinson FoundationUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:Asteroids; Asteroid dynamics; Main belt asteroids
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Asteroids (72); Asteroid dynamics (2210); Main belt asteroids (2036)
Record Number:CaltechAUTHORS:20210429-144554794
Persistent URL:
Official Citation:Josiah N. Purdum et al 2021 ApJL 911 L35
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108893
Deposited By: George Porter
Deposited On:30 Apr 2021 21:38
Last Modified:16 Nov 2021 19:33

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