TITLE: GCN CIRCULAR NUMBER: 21417 SUBJECT: GRB 170804A: LCO Observations DATE: 17/08/05 16:53:45 GMT FROM: Antonino Cucchiara at UVI A. Cucchiara, D. Morris (U. of the Virgin Islands), and N. Orange (OrangeWave), report on behalf of a larger collaboration: "On August 4.79 UT (T_0 +7.0h) we began observing the center of the field of GRB 170804A (Cholden-Brown et al. GCN 21410, Emery et al. GCN 21411) using the Las Cumbres Observatory 1m telescope located in Siding Spring Observatory. Under poor sky conditions (seeing ~2.6 arcseconds) we performed a series of 5x240s observations in SDSS r' and i’ bands for a total of 20 minutes on sky in each filter at average airmass of 1.3. In the full median stacked images we identified no optical counterpart within the center of the Swift-XRT refined position or at the UVOT optical counterpart location (Evans et al. GCN 21413, Emery et al. GCN 21411) at the following 3-sigma limits: r' > 21.4 mag i' > 21.1 mag These magnitudes are calibrated against nearby USNO-B1 sources, converted in SDSS bands, and not corrected for Galactic extinction."