{
  "bibcode": "2020GCN.26691....1K",
  "body": "F. Krauss, T. Gregoire, D.B. Fox, J. Kennea (PSU) and P. Evans\n(U. Leicester) report for AMON (https://amon.psu.edu/):\n\n\"We have observed the positions of the two Fermi/LAT sources (Garrappa\net al., GCN Circ. 26669), positionally coincident with the IceCube\nneutrino event IceCube-200107A (GCN Circ. 26655) with the Neil Gehrels\nSwift Observatory X-ray Telescope (XRT). We detect the blazar 4FGL\nJ0955.1+3551 with an observed 2-10 keV flux of 4.7 (+/- 0.8) x 10^-12\nerg cm-2 s-1 (2-10 keV). A spectrum constructed from these data can be \nwell described by an absorbed power law with N_H = 5.3 x 10^20 cm-2\n(wilm abundances, vern cross-sections), and a photon index of 1.8\n(+0.23, -0.13). These data have also been reported in ATel #13394. \n\nThis object has been previously observed by Swift/XRT, and its\nhistorical behavior can be seen in the 2SXPS catalogue (Evans et al.,\n2019):  https://www.swift.ac.uk/2SXPS/2SXPS%20J095507.8%2B355100\nOur recent observations are significantly brighter than the average\nflux in archival data: 1.78 (+0.14, -0.13) x 10-12 erg cm-2 s-1\n(observed 2-10 keV flux), although the historical light curve does\nshow that the source flux was gradually increasing in 2012 to\n2013. The catalogued ROSAT flux of this source (as 1RXS\nJ095508.2+355054) is 0.11 ct/sec which, assuming the above spectrum,\ncorresponds to a 2-10 keV observed flux of ~1.9 x 10-12 erg cm-2 s-1;\ntherefore we suggest that this source is currently in a high\nstate. Further observations of this source are strongly recommended. \n\nThe other source reported in GCN Circ. 26669 (4FGL J0957.8+3423) was\nnot detected in our observations, with a 3-sigma upper limit of 0.010\nct/sec (0.3-10 keV). Assuming a standard spectrum (N_H = 3 x 10^20\ncm-2, Gamma=1.7) this corresponds to a observed 2-10 keV flux upper\nlimit of 2.7 x 10-13 erg cm-2 s-1. This source has not been previously\ncovered by Swift/XRT observations.\"",
  "circularId": 26691,
  "createdOn": 1578599506000,
  "email": "dbf11@psu.edu",
  "subject": "Swift follow-up observations of IceCube-200107A: Identification of X-ray high state for 4FGL J0955.1+3551",
  "submitter": "Derek B. Fox at Penn State  <dbf11@psu.edu>",
  "eventId": "IceCube-200107A"
}