S. B. Cenko (NASA GSFC), E. Troja (NASA GSFC), and S. Tegler (NAU) report on behalf of a larger collaboration:
We imaged the location of the Fermi GBM (Roberts et al., GCN 19411), Fermi LAT (Longo et al., GCN 19403), and MAXI GSC (Ono et al, GCN 19405) GRB160509A with the Large Monolithic Imager on the 4.3 m Discovery Channel Telescope in Happy Jack, AZ. Observations were obtained in the g�, r�, i�, and z� filters beginning at 9:40 UT on 10 May 2016 (~ 1.03 d after the trigger).
At the location of the candidate optical afterglow (Levan et al., GCN 19410), we detect a source in all four filters. We report the following preliminary photometry (using nearby point sources from SDSS for calibration):
g� = 25.03 +/- 0.15
r� = 24.05 +/- 0.14
The source has faded since the Gemini observations reported by Levan et al. (GCN 19410), indicating that it is indeed the afterglow of GRB160509A. However, the detection in g� limits the host redshift to be z <~ 3.5, requiring significant dust extinction along the line of sight.