TITLE: GCN CIRCULAR NUMBER: 18335 SUBJECT: LIGO/Virgo G184098: Pan-STARRS1 observations of the northern sky region DATE: 15/09/20 01:30:42 GMT FROM: S. J. Smartt at Queens U Belfast K. Chambers, M. Huber, E. Magnier, H. Flewelling, C. Waters, J. Tonry, A. Schultz, N. Primak (IfA, University of Hawaii), S.J. Smartt, K. W. Smith, D. Young, D. Wright (QueenĂ¢<80><99>s University Belfast), C. Stubbs (Harvard) With the Pan-STARRS1 telescope (3 degree FOV) on Maui, Hawaii, we imaged the northern error region of the ALIGO GW burst trigger G184098 released on 2015-09-14. In the dawn twilight of 2015-09-17 (14:53-15:31 UT) we took a set of 9 images (3x3 grid), stepping through RA=129.8503, 132.5503, 135.2503 and DEC=3.699, 6.399, 9.099 in each of i and z (60s and 45s each respectively). One exposure, with some edge overlap was taken at each position, producing approximately 63 sq degrees coverage in i and z bands. A set of y-band images was taken at the central pointing position. The fill factor of the GPC1 camera on Pan-STARRS1 is about 80%, due to focal plane gaps. Difference imaging with respect to the PS1 3Pi stacked sky images is ongoing to identify any new transients candidates. Further imaging will be taken in this pattern as weather allows and reported in the GraceDB EM observations. Any candidates will be reported to this email list. [GCN OPS NOTE(19sep15): This Circular was originally published on 20:44 17-Sep-2015 UT.]