{
  "bibcode": "2017GCN.20419....1K",
  "body": "T. Kupfer (Caltech), R. Quimby (SDSU), S. M. Adams (Caltech), H. Vedantham\n(Caltech), M. M. Kasliwal (Caltech)\n\nreport on behalf of the GROWTH (Global Relay of Observatories Watching\nTransients Happen) and iPTF (intermediate Palomar Transient Factory)\ncollaborations\n\nWe report the spectroscopic follow-up observations on ATLAS17aeu (Tonry et\nal. LVC GCN #20382) and iPTF17cw (Kasliwal et al. LVC GCN #20398) using the\nDouble Beam spectrograph (DBSP) on the Palomar 200-inch telescope. The\nposition of both targets are within the probability contour of LIGO/Virgo\nG268556 (LVC, GCN #20364).  All observations were obtained on 2017 Jan 7 UT\nunder poor weather conditions with a partly cloudy sky. Classifications\nwere performed using Superfit (Howell et al. 2005, ApJ, 634, 1190).\n\nATLAS17aeu was observed on 2017-01-07.5 UT with a total exposure time of 60\nmin resulting in a signal to noise ratio ~1.5 in the continuum. No obvious\nemission or absorption lines are detected in the spectrum. To search for\nfeatures from a Galactic source at z=0, we set a 3-sigma flux limit around\n6563 Angstrom of 3.3e-17 ergs/s/cm^2/A. This result is consistent with\nChambers et al. (LVC GCN #20407) who reported a featureless spectrum of\nATLAS17aeu obtained with Gemini.\n\niPTF17cw was observed on 2017-01-07.55 with a total exposure time of 20 min\nwhich results in a signal to noise ratio ~11 in the continuum. The spectrum\nshows a blue continuum peaking around 3850 Angstroem (rest frame) with\nweak, broad features. We found a good match of the spectrum with the\nSNIc-BL SN1998bw pre-maximum at z=0.093. The redshift is consistent with\nthe photoz=0.101��0.0279 derived by SDSS for the host Galaxy.",
  "circularId": 20419,
  "createdOn": 1484067482000,
  "email": "mansi@astro.caltech.edu",
  "subject": "LIGO/Virgo G268556: Spectroscopic observations of ATLAS17aeu and iPTF17cw",
  "submitter": "Mansi M. Kasliwal at Caltech  <mansi@astro.caltech.edu>",
  "eventId": "LIGO/Virgo G268556"
}