TITLE: GCN CIRCULAR NUMBER: 17663 SUBJECT: GRB 150402A: RATIR Optical Observations DATE: 15/04/03 19:03:37 GMT FROM: Owen Littlejohns at Az State U Owen Littlejohns (ASU), Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja (GSFC), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We observed the field of GRB 150402A (Cummings, et al., GCN 17661) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2015/04 3.02 to 2015/04 10.92 UTC (26.39 to 34.29 hours after the BAT trigger), obtaining a total of 3.16 hours exposure in the r and i bands. Currently, there is only one source detected by the Swift/XRT within the Swift/BAT error circle (Evans, GCN 17662). RA(J2000) = 11h 34m 34.0s Dec(J2000) = +40d 58' 37.8" This source has an error circle of 6.2 arcseconds. We detect no uncatalogued transient inside the error circle for this source. In comparison with the SDSS DR9, we obtain the following upper limits (3-sigma): r > 22.75 i > 22.68 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.