TITLE:   GCN CIRCULAR
NUMBER:  24217
SUBJECT: LIGO/Virgo S190425z - ePESSTO+ spectrum of PS19qp shows red featureless source at z=0.037
DATE:    19/04/26 09:24:50 GMT
FROM:    Matt Nicholl at Royal Astronomical Soc.  <mrn@roe.ac.uk>

M. Nicholl, P. Short (Edinburgh), S. J. Smartt, K. W. Smith (QUB), K. Chambers, M. Huber (IfA) , J. Anderson (ESO), T.-W. Chen (MPE), C. Inserra (Cardiff), O. Yaron (Weizmann), D. R. Young (QUB), C. Angus, M. Pursiainen, P. Wiseman (Southampton), S. Taubenberger (MPA), M. Gromadzki (Warsaw) on behalf of the ePESSTO+ collaboration

We observed PS19qp (Smith et al., GCN 24210) a potential counterpart to the gravitational wave trigger S190425z (GCN 24168), under the advanced Public ESO Spectroscopic Survey for Transient Objects (ePESSTO+; see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org). The observations were performed on the ESO New Technology Telescope at La Silla with the EFOSC2 instrument.

The transient is coincident with a probable host galaxy 2MASS J17011849-0700102. Preliminary reduction of our NTT spectrum (1800s, Grism#13) shows a red and mostly featureless continuum, with a narrow H-alpha emission line, likely from the host galaxy, at z=0.037.

With this redshift and a foreground extinction of A_v = 1.3 mag (Schlafly & Finkbeiner 2011), the apparent magnitude of i=20.4 mag reported by Smith et al. corresponds to an absolute magnitude of -16.7. Further observations are in progress.