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Discovery and redshift of an optical afterglow in 71 deg^2: iPTF13bxl and GRB 130702A

Singer, Leo P. and Cenko, S. Bradley and Kasliwal, Mansi M. and Perley, Daniel A. and Ofek, Eran O. and Brown, Duncan A. and Nugent, Peter E. and Kulkarni, S. R. and Corsi, Alessandra and Frail, Dale A. and Bellm, Eric and Mulchaey, John and Arcavi, Iair and Barlow, Tom and Bloom, Joshua S. and Cao, Yi and Gehrels, Neil and Horesh, Assaf and Masci, Frank J. and McEnery, Julie and Rau, A. and Surace, Jason A. and Yaron, Ofer (2013) Discovery and redshift of an optical afterglow in 71 deg^2: iPTF13bxl and GRB 130702A. Astrophysical Journal Letters, 776 (2). Art. No. L34. ISSN 2041-8205. doi:10.1088/2041-8205/776/2/L34.

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We report the discovery of the optical afterglow of the γ-ray burst (GRB) 130702A, identified upon searching 71 deg^2 surrounding the Fermi Gamma-ray Burst Monitor (GBM) localization. Discovered and characterized by the intermediate Palomar Transient Factory, iPTF13bxl is the first afterglow discovered solely based on a GBM localization. Real-time image subtraction, machine learning, human vetting, and rapid response multi-wavelength follow-up enabled us to quickly narrow a list of 27,004 optical transient candidates to a single afterglow-like source. Detection of a new, fading X-ray source by Swift and a radio counterpart by CARMA and the Very Large Array confirmed the association between iPTF13bxl and GRB 130702A. Spectroscopy with the Magellan and Palomar 200 inch telescopes showed the afterglow to be at a redshift of z = 0.145, placing GRB 130702A among the lowest redshift GRBs detected to date. The prompt γ-ray energy release and afterglow luminosity are intermediate between typical cosmological GRBs and nearby sub-luminous events such as GRB 980425 and GRB 060218. The bright afterglow and emerging supernova offer an opportunity for extensive panchromatic follow-up. Our discovery of iPTF13bxl demonstrates the first observational proof-of-principle for ~10 Fermi-iPTF localizations annually. Furthermore, it represents an important step toward overcoming the challenges inherent in uncovering faint optical counterparts to comparably localized gravitational wave events in the Advanced LIGO and Virgo era.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Singer, Leo P.0000-0001-9898-5597
Cenko, S. Bradley0000-0003-1673-970X
Kasliwal, Mansi M.0000-0002-5619-4938
Perley, Daniel A.0000-0001-8472-1996
Ofek, Eran O.0000-0002-6786-8774
Brown, Duncan A.0000-0002-9180-5765
Nugent, Peter E.0000-0002-3389-0586
Kulkarni, S. R.0000-0001-5390-8563
Corsi, Alessandra0000-0001-8104-3536
Bellm, Eric0000-0001-8018-5348
Arcavi, Iair0000-0001-7090-4898
Bloom, Joshua S.0000-0002-7777-216X
Cao, Yi0000-0002-8036-8491
Horesh, Assaf0000-0002-5936-1156
Masci, Frank J.0000-0002-8532-9395
Rau, A.0000-0001-5990-6243
Surace, Jason A.0000-0001-7291-0087
Yaron, Ofer0000-0002-0301-8017
Alternate Title:Discovery and redshift of an optical afterglow in 71 square degrees: iPTF13bxl and GRB 130702A
Additional Information:© 2013 American Astronomical Society. Received 2013 July 20; accepted 2013 September 9; published 2013 October 7. We acknowledge A. Weinstein, A. Gal-Yam, R. Quimby, V. Connaughton, and the Fermi-GBM team for valuable discussions, S. Caudill, S. Tinyanont, D. Khatami for P200 observing, and the developers of the COSMOS package for Magellan data reduction. This research is supported by the National Science Foundation through a Graduate Research Fellowship for L.P.S., award PHY-0847611 for D.A.B., and NSF-CDI grant for J.S.B. M.M.K. acknowledges generous support from the Carnegie-Princeton Fellowship. M.M.K. and D.A.P. are supported by NASA through the Hubble Fellowship grants HST-HF-51293.01 and HST-HF-51296.01-A, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. E.O.O. is the incumbent of the Arye Dissentshik career development chair and is supported by grants from the Israeli Ministry of Science and the I-CORE Program. D.A.B. is further supported by an RCSA Cottrell Scholar award. This research made use of Astropy (Robitaille et al. 2013,, a community-developed core Python package for Astronomy. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
Group:Palomar Transient Factory, Infrared Processing and Analysis Center (IPAC), Division of Geological and Planetary Sciences
Funding AgencyGrant Number
NSF Graduate Research FellowshipPHY-0847611
Carnegie-Princeton FellowshipUNSPECIFIED
NASA Hubble FellowshipHST-HF-51293.01
NASA Hubble FellowshipHST-HF-51296.01-A
NASANAS 5-26555
Ministry of Science (Israel)UNSPECIFIED
Cottrell Scholar of Research CorporationUNSPECIFIED
Subject Keywords:gamma-ray burst: individual (GRB 130702A)
Issue or Number:2
Record Number:CaltechAUTHORS:20131104-131232227
Persistent URL:
Official Citation:Discovery and Redshift of an Optical Afterglow in 71 deg2: iPTF13bxl and GRB 130702A Leo P. Singer et al. 2013 ApJ 776 L34
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42224
Deposited By: Ruth Sustaita
Deposited On:04 Nov 2013 21:38
Last Modified:10 Nov 2021 16:20

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