[vsnet-grb-info 21979] LIGO/Virgo S190408an: MASTER OT is 27 day old ATLAS SN candidate and unrelated

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24078
SUBJECT: LIGO/Virgo S190408an: MASTER OT is 27 day old  ATLAS SN candidate and unrelated 
DATE:    19/04/09 09:08:52 GMT
FROM:    Stephen Smartt at Queen's U/Belfast  <s.smartt at qub.ac.uk>

S. J. Smartt, K. W. Smith, D. R. Young, O. McBrien, J. Gillanders. S. Srivastav,
D. O’Neil,  P. Clark, S. Sim (QUB),  L. Denneau, H. Flewelling, A. Heinze, 
J. Tonry, H. Weiland K. C. Chambers , M. Huber,  E. Magnier, 
A. Schultz, (IfA, Univ. Hawaii), A. Rest (STScI),  B. Stalder (LSST), 
C. Stubbs (Harvard)

Lipunov et al (GCN 24076) reported the discovery of an optical transient 
MASTER OT J140518.22-395309.9  close to the southern part of the 
skymap of LIGO/Virgo source S190408an. 

The ATLAS survey (Tonry et al. 2018, Stalder et al. 2016) has detected
this source since MJD=58555 (2019-03-13) at  o = 17.4. It peaked around 
MJD=58569 at o = 17 and has a SN like lightcurve. There is no obvious
catalogued host galaxy. 

In summary, we confirm the discovery of MASTER that this is a real 
optical transient (with no host galaxy) at coordinates : 

14:05:18.21 -39:53:10.0

211.32588 -39.88612

But that it is almost certainly a foreground SN about 1 month old, 
and very unlikely to be related to LIGO/Virgo S190408an.