Optical follow-up of IceCube-190503A with ZTF

ATel #12730; R. Stein (DESY), A. Franckowiak (DESY), J. van Santen (DESY), L. Rauch (DESY), M. M. Kasliwal (Caltech), I. Andreoni (Caltech), Tomas Ahumada (UMD), Michael Coughlin (Caltech), Leo P. Singer (NASA GSFC), Shreya Anand (Caltech)
on 5 May 2019; 18:23 UT
Credential Certification: Anna Franckowiak (anna.franckowiak@desy.de)

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On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations

We observed the localization region of the Extremely High Energy (EHE) neutrino track event IceCube-190503A (see GCN #24378 and https://gcn.gsfc.nasa.gov/notices_amon/42419327_132508.amon) with the Palomar 48-inch telescope equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019).

We obtained target-of-opportunity observations in the g-band and r-band filters at UT 2019-05-04 03:32 and UT 2019-05-04 04:45 (10 and 11h after the neutrino detection) with an exposure length of 300s.

The images were processed through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). Candidates were filtered using the AMPEL software package (see Nordin et al. 2019). After rejecting stellar sources (Tachibana and Miller 2018) and moving objects and applying machine learning algorithms (Mahabal et al. 2019), no convincing transient or significant variable activity was found in temporal coincidence with the neutrino arrival time within the 90% error contour.

The median 5 sigma upper limit for an isolated point source in our images was r > 21.3 and g > 21.0 mag for the observations made on May 4.

Ongoing observations of the area will continue as part of regular survey observations.

ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY, Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IIT-B, India; IIA, India; LJMU, UK; TTU, USA; and USyd, Australia. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert filtering and follow-up co-ordination is being undertaken by the GROWTH marshal system (Kasliwal et al. 2019).