{
  "bibcode": "2017GCN.20407....1C",
  "body": "K. C. Chambers (IfA), S. Smartt (QUB), J. Tonry, L. Denneau,\nA. Heinze, B. Stalder, H. Weiland (IfA), C. W. Stubbs (Harvard),\nK. W. Smith (QUB), T.-W. Chen (MPE), T. Kruehler (MPE), D. R. Young\n(QUB), A. Rest (STScI), M. Coughlin (Harvard), M. E. Huber (IfA),\nD. E. Wright (QUB), H. Flewelling, E. A. Magnier, A. S. B. Schultz,\nC. Waters, R. J. Wainscoat (IfA)\n\nFurther to our discovery of ATLAS17aeu (Tonry et al. GCN 20382), we \ntook a spectrum with Gemini-North + GMOS (R400 grating, \n4491-8778 Angs) on MJD = 57761.595. We also took an r-band image \non the same night. \n\nThe spectrum has a blue featureless continuum, with a signal-to-noise\nin the continuum S/N~10 at 7000Angs.  There are no clear emission or\nabsorption lines visible that can anchor a redshift estimate.\n\nThe spectrum is not unlike some GRB afterglows as shown in the compilation\nof Fynbo et al. 2009, ApJS 185, 526 \ne.g. GRB060512, at z~2.1, GRB061110A (z=0.7578), GRB070129 (no z\nestimate, but below z<3.4)\n\nWe report three more photometric points, two from Pan-STARRS1 and \nthe other from Gemini+GMOS. \n\nMJD           Mag           Telescope \n57758.38159   18.18 0.04 i  Pan-STARRS1\n57759.46468   20.90 0.12 i  Pan-STARRS1\n57761.51968   22.77 0.17 r  Gemini+GMOS \n\nThese data further support the hypothesis of Kasliwal et al. GCN 20393\nthat this is most likely the afterglow of GRB170105A, supported by the\nx-ray and radio detections of Evans et al. GCN 20390 and Corsi et al.\nGCN 20396.\n\nUsing the POLAR detection time, a temporal index of F_nu \\propto\nt**(-1.4) would be consistent with the photometry reported to date,\ntypical of GRB afterglows.\n\nWe note there are several other faint galaxies closer to ATLAS17aeu\nthan the brighter galaxy at z = 0.199 highlighted in Tonry et al. (GCN\n20382). They have SDSS photometric redshifts of z ~ 0.35 - 0.38, but\nare marginal detections in more than one band and therefore the \nphotometric redshifts are uncertain.",
  "circularId": 20407,
  "createdOn": 1483980742000,
  "email": "s.smartt@qub.ac.uk",
  "subject": "LIGO/Virgo G268556: Gemini spectrum and Pan-STARRS observations of ATLAS17aeu",
  "submitter": "S. J. Smartt at Queens U Belfast  <s.smartt@qub.ac.uk>",
  "eventId": "LIGO/Virgo G268556"
}