TITLE: GCN CIRCULAR NUMBER: 21536 SUBJECT: LIGO/Virgo G298048: Inspection of archival HST data at the position of the potential optical counterpart DATE: 17/08/18 03:01:20 GMT FROM: Edo Berger at Harvard U R. J. Foley, C. D. Kilpatrick (UCSC), M. Nicholl, E. Berger (Harvard) report: The position of the potential optical counterpart (Coulter et al., LVC GCN 21529, Allam et al. LVC GCN 21530, Yang et al. LVC GCN 21531, Melandri et al. LVC GCN 21532) to the LIGO/Virgo G298048 trigger (LVC GCNs 21509, 21513) was imaged by the Hubble Space Telescope on 2017 April 28 UT with ACS in the F606W filter (Program ID: 14840; PI Bellini; 696 sec exposure time) as part of the "Schedule Gap Pilot Program." Examining the image we do not detect any sources within 2.2" of the nominal position to a 5-sigma limiting magnitude of ~25.9 mag, corresponding to M_V ~ -7.2 mag at a distance of 36 Mpc. We also note that the possible host galaxy, NGC 4993, has obvious dust lanes near its nucleus and extending out ~5" from the nucleus (corresponding to ~1 kpc at 36 Mpc). ------------------------------------------------- Edo Berger Professor of Astronomy Harvard University 60 Garden St. MS-19 Cambridge, MA 02138 USA Ph. 617-495-7914 / F. 617-258-7467 http://www.cfa.harvard.edu/~eberger -------------------------------------------------