GCN Circular 24284

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
Not found
 
 
) 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.