{
  "bibcode": "2017GCN.21533....1C",
  "body": "P. S. Cowperthwaite (Harvard),  R. J. Foley (UCSC), E. Berger (Harvard),\n\nWe investigate ASAS-SN public data at the position of the transient source\nSSS17a (RA = 13:09:48.09 DECL. = -23:22:53.35, Coulter et al. 2017 GCN\n21529). This source is also seen in DECam observations (Chornock et al. GCN\n21530) and DLT data (Yang et al. GCN 21531).\n\nWe search the last 100 days of available data, finding no strong evidence\nfor variability at this position. The most recent observation is UT =\n2017-08-14.9933703 (HJD = 2457980.49073), approximately 2 days before the\nGW trigger.\n\nThe data can be found here:\n\nhttps://asas-sn.osu.edu/public/light_curve/ede9a693-78be-4049-85a0-7de11bc61c3a\n\nThe photometry is generated by placing an aperture at the indicated\ncoordinates, and therefore includes light from the host galaxy.\n\nThe light curve is flat with a mean magnitude of 13.45 mag with a scatter\nof 0.05 mag. This indicates that the transient is most likely a young\nsource.\n\nThis circular makes use of ASAS-SN public data obtained from\nhttps://asas-sn.osu.edu/ (Shappee, B. J., Prieto, J. L., Grupe, D.,\net al. 2014, ApJ, 788, 48; Kochanek, C. S., Shappee, B. J., Stanek, K.\nZ., et al. 2017, PASP, 129, 104502).\n\n[GCN OPS NOTE(18oct17):  Per author's request, the last paragraph was added.]",
  "circularId": 21533,
  "createdOn": 1503021990000,
  "email": "pcowperthwaite@cfa.harvard.edu",
  "subject": "LIGO/Virgo G298048: Optical Candidate Shows No Evidence for Previous Activity in Archival ASAS-SN Data",
  "submitter": "Philip Cowperthwaite at Harvard U  <pcowperthwaite@cfa.harvard.edu>",
  "eventId": "LIGO/Virgo G298048"
}