TITLE: GCN CIRCULAR NUMBER: 21894 SUBJECT: LIGO/Virgo G298048: Desert Fireball Network simultaneous optical observations of the SSS17a/DLT17ck. DATE: 17/09/18 13:45:29 GMT FROM: David Kaplan at UW-Milwaukee P. J. Hancock, S. J. Tingay, J. S. de Gois, T. Booler (ICRAR, Curtin University), H. A. R. Devillepoix, P. A. Bland, M. C. Towner, E. K. Sansom, R. M. Howie (DFN, Curtin University), D. L. Kaplan (UWM) The Desert Fireball Network (DFN) is a network of 50 remote cameras located in the Western and South Australian desert designed for the detection and triangulation of Fireballs and bright meteors. The DFN cameras consist of a Nikon D800E camera equipped with a Samyang 8mm f/3.5 UMC Fish-eye CS II lens. The cameras capture full sky images with a cadence of 30s from sunset to sunrise every night of the year. We retrieved images from a camera located at Wooleen Station (27.0872 deg S, 116.1611 deg E). We analysed the images from the 17th of August from 12:39:28-12:49:28 UT: 2 minutes before the GW trigger to 7 minutes after. At this time the host galaxy NGC 4993 was at 20 degrees elevation, reducing the image sensitivity from 6th to 4th magnitude. The images show no persistent or transient sources in a 3 degree radius of NGC 4993, to a limiting visual magnitude of +4.