Difference: GCNCIRCULAR21784 ( vs. 1)

W. Fong, R. Margutti (Northwestern), D. Haggard (McGill) report on behalf of a larger collaboration:

We observed the field of the EM counterpart to the LVC trigger G298048 with the Chandra X-ray Observatory (CXO) starting on 2017-08-19T17:10:09UT (PI Fong). We do not find evidence for significant X-ray emission at the location of the optical transient (RA= 13:09:48.08, Dec= -23:22:53.2, Coulter et al. LVC GCN 21529; Allam et al., LVC GCN 21530; Sheng Yang et al., 21531; Chambers et al. LVC GCN 21553).

An extended X-ray source is clearly detected at: RA= 13:09:47.7 dec= -23:23:02.0

This position is consistent with the radio source that we identified in Alexander et al. (LVC GCN 21589) and it is centered on the host-galaxy optical position. Based on preliminary analysis, we estimate a flux ~1e-14 erg/s/cm2 in the 0.3-10 keV band.

The CXO X-ray source lies outside the 90% containment, but within the 3-sigma containment, of the localization region of the Swift-XRT source (Evans et al., LVC GCN 21612). The flux inferred by Evans et al., Fx=2.6 (+1.1, -0.9) e-14 erg/cm^2/s is also consistent with our results. We thus suggest that the X-ray source identified by Swift-XRT is most likely emission from the host galaxy.

We thank Belinda Wilkes and the entire Chandra team for their great support with these observations.

-- ThomasKupfer - 02 Sep 2017