@article{f0f0989f02914dd785a2ecda4bb09ac6,
title = "Swift/UVOT follow-up of gravitational wave alerts in the O3 era",
abstract = "In this paper, we report on the observational performance of the Swift Ultra-violet/Optical Telescope (UVOT) in response to the gravitational wave (GW) alerts announced by the Advanced Laser Interferometer Gravitational Wave Observatory and the Advanced Virgo detector during the O3 period. We provide the observational strategy for follow-up of GW alerts and provide an overview of the processing and analysis of candidate optical/UV sources. For the O3 period, we also provide a statistical overview and report on serendipitous sources discovered by Swift/UVOT. Swift followed 18 GW candidate alerts, with UVOT observing a total of 424 deg2. We found 27 sources that changed in magnitude at the 3σ level compared with archival u- or g-band catalogued values. Swift/UVOT also followed up a further 13 sources reported by other facilities during the O3 period. Using catalogue information, we divided these 40 sources into five initial classifications: 11 candidate active galactic nuclei (AGNs)/quasars, three cataclysmic variables (CVs), nine supernovae, 11 unidentified sources that had archival photometry, and six uncatalogued sources for which no archival photometry was available. We have no strong evidence to identify any of these transients as counterparts to the GW events. The 17 unclassified sources are likely a mix of AGN and a class of fast-evolving transient, and one source may be a CV.",
author = "Oates, {S. R.} and Marshall, {F. E.} and Breeveld, {A. A.} and Kuin, {N. P.M.} and Brown, {P. J.} and {De Pasquale}, M. and Evans, {P. A.} and Fenney, {A. J.} and C. Gronwall and Kennea, {J. A.} and Klingler, {N. J.} and Page, {M. J.} and Siegel, {M. H.} and A. Tohuvavohu and E. Ambrosi and Barthelmy, {S. D.} and Beardmore, {A. P.} and Bernardini, {M. G.} and S. Campana and R. Caputo and Cenko, {S. B.} and G. Cusumano and A. D'A{\`i} and P. D'Avanzo and V. D'Elia and P. Giommi and Hartmann, {D. H.} and Krimm, {H. A.} and S. Laha and Malesani, {D. B.} and A. Melandri and Nousek, {J. A.} and O'Brien, {P. T.} and Osborne, {J. P.} and C. Pagani and Page, {K. L.} and Palmer, {D. M.} and M. Perri and Racusin, {J. L.} and T. Sakamoto and B. Sbarufatti and Schlieder, {J. E.} and G. Tagliaferri and E. Troja",
note = "Funding Information: The CSS survey is funded by the National Aeronautics and Space Administration under grant no. NNG05GF22G issued through the Science Mission Directorate Near-Earth Objects Observations Program. The CRTS survey is supported by the U.S. National Science Foundation under grants AST-0909182 and AST-1313422. This publicationmakes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. The CFHTLS data are based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/IRFU, at the Canada-France- Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the InstitutNational des Science de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at Terapix available at the Canadian Astronomy Data Centre as part of the Canada-France- Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. This research has made use of the NASA/IPAC Infrared Science Archive, which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology. The Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan- STARRS Project Office, theMax-Planck Society and its participating institutes, the Max-Planck Institute for Astronomy, Heidelberg, the Max-Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under grant no. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, theNational Science Foundation grant no. AST- 1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. SRO gratefully acknowledges the support of the Leverhulme Trust Early Career Fellowship. AAB, NPMK, MJP, KLP, PAE, APB, and JPO acknowledge funding from the UK Space Agency. MDP acknowledges support for this work by the Scientific and Technological Research Council of Turkey (T{\"U}BITAK), grant no: MFAG-119F073. EA, MGB, SC, GC, AD, PDA, AM, and GT acknowledge funding from the Italian Space Agency, contract ASI/INAF n. I/004/11/4. This work is also partially supported by a grant from the Italian Ministry of Foreign Affairs and International Cooperation Nr. MAE0065741. PDA acknowledges support from PRIN-MIUR 2017 (grant 20179ZF5KS). DBM is supported by research grant 19054 from Villum Fonden. Publisher Copyright: {\textcopyright} 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.",
year = "2021",
month = oct,
day = "1",
doi = "10.1093/mnras/stab2189",
language = "English (US)",
volume = "507",
pages = "1296--1317",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "1",
}