TITLE:   GCN CIRCULAR
NUMBER:  18451
SUBJECT: LIGO/Virgo G194575: more details on transients from Pan-STARRS in the RA=1hr localisation region
DATE:    15/10/23 15:27:09 GMT
FROM:    S. J. Smartt at Queens U Belfast  <s.smartt@qub.ac.uk>

K. Chambers, M. Huber, (IfA, University of Hawaii), K. W. Smith, 
D. Young, D. Wright, S.J. Smartt (Queen’s University Belfast), (QUB) E. Magnier,
H. Flewelling, C. Waters, J. Tonry, A. Schultz, N. Primak 
A. Heinze, B. Stalder, L. Denneau, A. Sherstyuk (IfA), C. Stubbs, M. Coughlin (Harvard), A. Rest (STScI)

Further to GCN 18445, we report that 7 transients were discovered within 
the 45% probability contour of the RA=1hr blob between the dates 
2015-10-16 and 2015-10-21. G194575 was reported with a time stamp of
2015-10-22 13:33:20 UTC, hence these first detections are a few
days before. They should be useful to other surveys to weed out any freshly 
appearing transients from existing ones. 

These are all likely supernova with identifications :  
PS15ckv, PS15clm, PS15cmc, PS15cll, PS15ckt, PS15cmj and PS15cng. 

All details for these transients are on 
http://star.pst.qub.ac.uk/ps1threepi/psdb/
We note the bright transient PS15cng (i=18.6) in MCG -01-59-024 (145 Mpc)

In addition, two new transients were detected at 2015-10-22 07:34 UTC and 
2015-10-22 07:32 UTC (6hrs before the GW event) 

PS15coc	00:28:48.57 -02:42:35.8 18.18(i)
PS15coa	00:16:47.00 -02:25:10.0 20.28(i)

They are both offset from obvious SDSS host galaxies by 7” and 5.5”, but
no catalogued redshifts are available. Again, these are likely to be unrelated field supernovae
given their discovery before the GW event, and unrestrictive limits on their explosion epochs. 
Further analysis and observations are ongoing.