{
  "bibcode": "2017GCN.21553....1C",
  "body": "K. C. Chambers (IfA), M. E. Huber (IfA), S. J. Smartt, (QUB),\nK. W. Smith (QUB), D. R. Young, M. Coughlin (Harvard), T.-W. Chen\n(MPE), L. Denneau, H. Flewelling, A. Heinze, E. Kankare (QUB),\nT. Lowe, E. A. Magnier (IfA), A. Rest (STScI), B. Stalder (IfA),\nA. S. B. Schultz, C. W. Stubbs (Harvard) J. Tonry, C. Waters,\nR. J. Wainscoat, H. Weiland, M. Willman (IfA), D. E. Wright (QUB)\n\nWe report Pan-STARRS imaging observations of the the skymap of\nG298048. A set of six images were taken, in twilight and at low\nairmass. We had planned to tile the northern part of the skymap, but\nafter the discovery of the transient SSS17a/DLT17ck in GCN 21529\n(Coulter et al) and 21531 (Valenti et al.) we immediately switched to\ncover the NGC4993 in 2x30s in each of Pan-STARRS i, z, y, ensuring the\npostion of the transient object was on a good, clean CCD cell.\n\nDifference images were produced by subtracting the Pan-STARRS1 3Pi\nreference image from these separate 30s exposures (Chambers et\nal. arXiv:1612.05560, and available at http://panstarrs.stsci.edu).\n\nWe recover the transient as Pan-STARRS object PS17gl at coordinates \n\nRA = 13:09:48.08  DEC = -23:22:53.2 \nRA = 197.45033    DEC = -23.38144 \n\nImage log and photometry in the Pan-STARRS system (Tonry et al. 2012\nMagnier et al. arXiv:1612.05242)  : \n\n\nDate (UT)             RA            DEC            Exp  Filt Airmass\n2017-08-18T05:33:01  198.347081   -23.075627 2000  30.0 y    2.83   17.28 0.13\n2017-08-18T05:33:46  198.347076   -23.075658 2000  30.0 z    2.84   17.31 0.09\n2017-08-18T05:34:31  198.347062   -23.075632 2000  30.0 i    2.86   17.23 0.10\n2017-08-18T05:35:45  198.347073   -23.075633 2000  30.0 y    2.89   17.47 0.16\n2017-08-18T05:36:30  198.347070   -23.075638 2000  30.0 z    2.91   17.21 0.08\n2017-08-18T05:37:14  198.347060   -23.075617 2000  30.0 i    2.93   17.26 0.08\n\nThere is no evidence, within the uncertainties for fading between the\nexposures. If the Swope 1m photometry point of i=16 (Coulter et al.)\nis correct then this would imply substantial fading. But this needs\nchecked, since DLT17ck was reported at R=17.3, is more consistent with \nthe colours we measure :\n\ni - z = -0.02 +/- 0.02\nz - y = -0.26 +/- 0.18 \n\nThis is consistent with the DECam photometry by Nicholl et\nal. (GCN21541) and that within the uncertainties, the colours are\nconsistent with 0, and being flat in Fnu as reported by the J-band\ndetection of Tanvir & Levan (GCN21544). Further observations are\nplanned with the same filter setup as long as the target is\nobservable, or firmly ruled out as a counterpart to G298048.",
  "circularId": 21553,
  "createdOn": 1503045440000,
  "email": "s.smartt@qub.ac.uk",
  "subject": "LIGO/Virgo G298048: Pan-STARRS detections and izy photometry of the possible optical/NIR counterpart in NGC4993",
  "submitter": "S. J. Smartt at Queens U Belfast  <s.smartt@qub.ac.uk>",
  "eventId": "LIGO/Virgo G298048"
}