TITLE: GCN CIRCULAR NUMBER: 24335 SUBJECT: LIGO/Virgo S190425z: RATIR non-detection of the Swift/UVOT source DATE: 19/04/28 22:39:18 GMT FROM: Eleonora Troja at NASA/GSFC/UMD Eleonora Troja (GSFC/UMD), Alan M. Watson (UNAM), Rosa L. Becerra (UNAM), Nat Butler (ASU), Diego Gonzalez (UNAM), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Margarita Pereyra (UNAM), and Tanner Wolfram (ASU) report: We observed the location of the Swift/UVOT transient (Breeveld et al., GCN Circ. 24296) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio AstronĂ³mico Nacional on Sierra San Pedro Martir from 2019/04 28.28 to 2019/04 28.49 UTC (approximately 3 d after the GW trigger), obtaining a total of 1.92 hours exposure in the r and i bands and 1.21 hours exposure in the Z, Y, J, and H bands. For a source within the UVOT error circle, in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma): g > 23.5 r > 23.4 i > 23.3 Z > 22.2 Y > 22.2 J > 21.8 H > 21.4 The nearby objected reported by Palmese et al. (GCN Circ. 24312) is detected in our images at H~20.1 mag. 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 Astronomico Nacional in San Pedro Martir