Difference: GCNCIRCULAR21626 ( vs. 1)

F. A. Harrison, K. Forster, J. Garcia, B. W. Grefenstette, M. Heida, M. M. Kasliwal, K. K. Madsen, H. Miyasaka, S. Pike, V. Rana, Y. Xu (Caltech)

We obtained X-ray imaging of the optical counterpart of SSS17a (Coulter et al.; GCN21529), the candidate optical counterpart of G298048 (LVC; GCN 21509) in the 3 – 79 keV band with NuSTAR. Observations began at 2017-08-18T05:26:09 UT and ended at 2017-08-18T19:46:09, with a total exposure of 24 ksec. We did not detect any X-ray emission in a circular 50’’ extraction region centered on the position of the optical counterpart, with a 3-sigma threshold of 1.4 x 10-14 erg/cm^2/s in the 3-10 keV band, assuming an X-ray spectrum with a photon power law index of -2. No source was detected in the 10-60 keV band, however additional analysis is ongoing to place limits on possible line emission from nuclear decays. We note that the NuSTAR hard X-ray band is not sensitive to X-ray emission from star formation in the host galaxy, and there is no known AGN activity in this source.

Further NuSTAR observations are planned.

-- DeepChatterjee - 21 Aug 2017