TITLE: GCN CIRCULAR NUMBER: 18569 SUBJECT: LIGO/Virgo G194575: Swift observations if iPTF15dld DATE: 15/11/09 14:30:20 GMT FROM: Phil Evans at U of Leicester Phil A. Evans (U. Leicester), Jamie A. Kennea (PSU), Scott Barthelmy (NASA/GSFC), Dave Burrows (PSU), Sergio Campana (INAF-OAB), Brad Cenko (NASA/GSFC), Neil Gehrels (NASA/GSFC), Paolo Giommi (ASI), Frank Marshall (NASA/GSFC), John Nousek (PSU), Paul O'Brien (U. Leicester), Julian Osborne (U. Leicester), David Palmer (LANL), Matteo Perri (ASDC), Judy Racusin (NASA/GSFC), Mike Siegel (PSU), Gianpiero Tagliaferri (INAF-OAB) on behalf of the Swift team: P. D'Avanzo (INAF-OAB), S. Piranomonte (INAF-OAR), E. Cappellaro (INAF-OAPd), M. Branchesi (Urbino University/INFN Pisa), E. Brocato (INAF-OAR) on behalf of the INAF-GW collaboration: Alessandra Corsi (Texas Tech), Shri Kulkarni (Caltech), Mansi Kasliwal (Caltech), Dale Frail (NRAO) Avishay Gal-Yam (Weizmann Institute) on behalf of the iPTF team: Swift has observed the location of iPTF15dld (Singer at al., LVC Circ. 18497), which may be a type Ic supernova (Benetti et al., LVC Circ. 18563). The observations were gathered from 15.4 d to 15.9 d after the aLIGO trigger, for a total of 10 ks observing time. No X-ray emission is detected from iPTF15dld, with a 3-sigma upper limit of 9.8e-4 ct/sec; this corresponds to an approximate 0.3-10 keV flux limit of 4.9e-14 erg cm^-2 s^-1. Swift-UVOT detected a bright source with a magnitude of 17.51 +/- 0.10 in the uvw1 filter, however this lies within the host galaxy, whose uvw1 magnitude is not known, thus the above magnitude is a combination of host+source. Once the transient has faded, we will perform repeat observations to measure the host flux and determine the correct transient magnitude. These Swift observations were performed in part through the Swift-GI program 1114155 (PI: Corsi). This circular is an official product of the Swift GW follow-up team.