TITLE: GCN CIRCULAR NUMBER: 19454 SUBJECT: GRB 160425A: SMARTS late-time observations DATE: 16/05/24 18:35:05 GMT FROM: Bethany Cobb at GWU B. E. Cobb (GWU), reports: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained additional optical/IR imaging of the error region of GRB 160425A (GCN 19343, Krimm et al.) at 7.3, 18.4 and 26.4 days post-burst. For each epoch, total summed exposure times amounted to 36 minutes in I and 30 minutes in J. The possible host of GRB 160425A (GCN 19350, Tanvir et al., GCN 19351, Balanutsa et al.) is observed in these images. This object appears as two separate knots and, therefore, may be a merging pair of galaxies (GCN 19350, Tanvir et al.). The object, with a magnitude of I~20.1 (calibrated using USNO-B1.0 stars), exhibits no significant changes in brightness between 7 and 26 days post-burst, though changes in brightness of less than 0.05 magnitudes cannot be ruled out by the data. In this type of host, at a redshift of z=0.555 (GCN 19350, Tanvir et al.), a 1998bw-like supernova would be expected to increase the brightness of the host by approximately 0.1 magnitudes, and can therefore be excluded. If this unusual burst (GRB GCN 19343, Krimm et al.) is actually a long-duration GRB, than any associated supernova must be dimmer at peak than SN 1998bw.