TITLE: GCN CIRCULAR NUMBER: 21908 SUBJECT: LIGO/Virgo G298048: LCO FLOYDS and Gemini Spectroscopy DATE: 17/09/22 03:24:44 GMT FROM: Curtis McCully at Las Cumbres Observatory C. McCully, D. A. Howell, G. Hosseinzadeh, D. Hiramatsu, I. Arcavi, S. Vasylyev (UCSB/Las Cumbres Obs), S. Valenti (UC Davis) and L. P. Singer (NASA/GSFC), C. Fremling (Caltech), and M. M. Kasliwal (Caltech) on behalf of the GROWTH (Global Relay of Observatories Watching Transients Happen) collaboration report: We observed the optical transient, SSS17a/DLT17ck (Coulter et al., LVC GCN 21529) on 2017-08-19 08:36:22, +1.83 days after the LIGO/Virgo trigger G298048 (LVC GCN Circ. 21509, 21513), for one hour with the robotic FLOYDS instrument mounted on the Las Cumbres Observatory Faulkes Telescope South at the Siding Spring Observatory in Australia. We detect the continuum of the transient at low signal-to-noise level. We also observed SSS17a/DLT17ck on 2017-08-20 01:01:54, +2.51 days after the LIGO/Virgo trigger, with the Gemini Multi-Object Spectrograph (GMOS) on the Gemini-South 8-m telescope. We observed in our red setting for 763 seconds and 128 seconds in our blue setting until the telescope reached its altitude limit. We again detect the continuum at low signal to noise level due to the high airmass at which the observations were made and the limited exposure times due to observing constraints. We thank the LCO staff, specifically Mark Bowman and Mark Willis, and the Gemini staff, specifically Karleyne Silva and Laura Ferrarese, for their assistance with these observations.