TITLE: GCN CIRCULAR NUMBER: 24284 SUBJECT: LIGO/Virgo S190426c: Infrared Wide-field Search with Palomar Gattini-IR DATE: 19/04/27 14:47:20 GMT FROM: Kishalay De at Caltech, GROWTH M. Hankins (Caltech), K. De (Caltech), M. Coughlin (Caltech), M. M. Kasliwal (Caltech), S. M. Adams (Caltech), I. Andreoni (Caltech), S. Anand (Caltech), L. Singer (NASA GSFC), T. Ahumada (UMD), A. Moore (ANU), J. Soon (ANU), M. Ashley (UNSW), T. Travouillon (ANU) report on behalf of the Palomar Gattini-IR team and the larger GROWTH (Global Relay of Observatories Watching Transients Happen) collaboration We report wide-field near-infrared follow-up observations of the localization region of the gravitational wave event S190426c (GCN #24237) by the Palomar Gattini-IR survey (Moore and Kasliwal 2019). Gattini-IR is a newly commissioned near-IR camera with a field of view of 25 square degrees mounted on a robotic 30 cm telescope at Palomar observatory. We started customized Target of Opportunity observations at UT 2019-04-27 03:31. The tiling was optimally determined and triggered using the GROWTH Target of Opportunity marshal (Coughlin et al. 2019a, Kasliwal et al. 2019b). We imaged a total of 2200 square degrees, covering 92% of the probability region of the event for 1 to 4 epochs until UT 2019-04-27 13:21. Each field visit consisted of a sequence of 8 dithers of 8 second exposures each on the field, which were processed and stacked with the Palomar Gattini-IR data reduction pipeline (De et al., in prep.). The typical limiting magnitude of each stacked epoch (64 second exposure time) was between 14.5 and 15 AB mag in J-band, and shallower than usual due to poor weather conditions. Transient vetting is ongoing and any viable counterparts will be announced.