GCN Circular 18445

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

Report several transients discovered in and around the 
RA=1hr DEC=+4deg error region as defined in the BAYESTAR 
skymap.fits file. 

This area has been covered in the w and i-bands 
during the routine course of the Pan-STARRS Survey for Transients
(see Huber et al. 2015, ATel 7153 and http://star.pst.qub.ac.uk/ps1threepi/psdb/)
and around 10 supernova candidates are known from the last 
7 days of observations in this region. These are almost certainly all 
unrelated to the GW trigger, as they were discovered days before the 
LIGO/Virgo detection. Details are available on the public webpage above. 

For example, the most recent discovery is a i=18.6 supernova candidate at 
7.2��� from the core of MCG -01-59-024 at z=0.033. This was discovered on 57315.31, 
54h before the GW trigger (at position 23:28:24.29 -02:47:57.8)

Pan-STARRS was observing the RA=1hr localisation region (south of dec=0), 
during the night of 2015-10-22. However the observations were taken 5-6hrs
before the LIGO/Virgo detection. Difference imaging and transient searches
are underway and further observations are planned for the 
coming nights. We plan to cover this RA=1hr region with the PS1 1.8m
telescope, 7 sq degree camera, in i and z bands.