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GCN Circular 25384

Subject
LIGO/Virgo S190814bv : ENGRAVE X-shooter spectra of AT2019nqs and AT2019npy
Date
2019-08-17T16:58:21Z (5 years ago)
From
Andrew Levan at U.of Leicester <a.levan@astro.ru.nl>
S. H. Bruun (DARK/NBI), A. Sagues Carracedo (OKC), T.-W. Chen (MPE), C. Copperwheat (LJMU), P. D'Avanzo (INAF), M. Fraser (UCD), K. E. Heintz (U. Iceland), J. Hjorth (DARK/NBI), J. Japelj (API, Amsterdam), P. Jonker (SRON/Radboud Univ.), G. Leloudas (DTU Space), A. J. Levan (Radboud Univ),  D. B. Malesani (DTU Space), I. Mandel (Monash), D. A. Perley (LJMU), N. B. Sabha (Univ. Innsbruck), S. Schulze (Weizmann), S. Smartt (QUB), J. Sollerman (OKC), D. Steeghs (Warwick), S. D. Vergani (Paris Observatory-CNRS) report on behalf of the ENGRAVE collaboration:

We obtained spectroscopy of transients located within the error region of S190814bv (LVC GCN 25333). Observations were taken of desgw-190814e (AT2019nqs: Herner et al., GCN 25373; Dichiara et al., GCN 25374) and DESsevhc (AT2019npy; Andreoni et al., GCN 25362) with the VLT equipped with X-shooter on 17 August 2019.

The spectrum of desgw-190814e (AT2019nqs) exhibits clear emission lines of H-alpha and [N II] at a redshift of z = 0.1263 +/- 0.001. The continuum contains significant host galaxy contamination, but is consistent with an old type Ia or Ibc supernova (around 20-50 days post-maximum) whose sub-type cannot be reliably determined.  This classification was determined using DASH (Muthukrishna et al. 2019), redshift of 0.126, and adding host contamination (Sa-type spectrum at roughly 60%). More refined classification will require further work. This redshift corresponds to a distance of almost 600 Mpc and lies >6 sigma from the inferred GW distance. We therefore conclude that desgw-190814e is not associated with S190814bv.

No discrete features are readily identified in the noisy spectrum of DESsevhc (AT2019npy). The source exhibits a red continuum but no obvious broad lines from a transient or narrow emission lines from a host galaxy. The source does not appear spectrally similar to AT2017gfo.

We thank the staff at Paranal for their excellent assistance with these observations. 

Based on observations collected by the ENGRAVE collaboration at the European Southern Observatory under ESO programmes 1102.D-0353, 0103.D-0703, 0103.D-0722 (for further information on ENGRAVE see http://www.engrave-eso.org/).
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