{
  "bibcode": "2017GCN.22196....1R",
  "body": "Dado, Dar and De Rujula report:\n\nThe very bright radio afterglow^1 of the far off-axis (low luminosity)\nGRB171205A at the outskirts of its host galaxy^2 at redshift z=0.0368\n(agular distance Da~ 150 Mpc), provides another rare opportunity, like\nGRBs^3 980425 and 030329, to measure the apparent hyperluminal separation\nof the jet-produced afterglow from the anticipated supernova, which\nlaunched it^3. The CB model relation Ep \\propto Eiso^{1/3} for far \noff-axis GRBs^4, and its estimated isotropic energy release in the \nobserved 15-150 keV band^5, Eiso~ 5.7E49 erg, yield, in the CB model^3, \nEp~100 keV, viewing angle of @~(2/Ep(eV))^1/2~4.5 mrad, and a hyperluminal\nvelocity^3 V~ 2c/@ ~450c.\n\nWith such a hyperluminal velocity, the radio afterglow separation from the\nSN, which launched it, will reach ~ 200 mas! after a year, easily resolved \nin VLBI and VLA radio follow-up observations.\n\nIf the afterglow of GRB171205A was a SN-less^6 GRB, produced by a highly\nrelativistic jet launched in a phase transition of a neutron star\n(to quark star ?), the above estimate will not be valid for the separation\nof the radio afterglow from the GRB position, if its late-time afterglow\nwas produced by a highly magnetized millisecond pulsar^7 (MSP).\n\nWe strongly urge VLA and VLBI follow up observations of the radio \nafterglow of GRB171205A.\n\n1. A. de Ugarte Postigo, et al. GCN 22187\n2. L. Izzo, et al. GCN 22180\n3. S. Dado, A. Dar and A. De Rujula, arXiv:1610.01985\n4. S. Dado and A. Dar, arXiv:1708.04603\n5. S. D. Barthelmy, et al. GCN 22184\n6. D. A. Perley and K. Taggart GCN 22194\n7. S. Dado, A. Dar  arXiv:1710.02456",
  "circularId": 22196,
  "createdOn": 1512646114000,
  "email": "arnon@physics.technion.ac.il",
  "subject": "GRB171205A hyperluminal radio afterglow?",
  "submitter": "Arnon Dar at Technion-Israel Inst. of Tech  <arnon@physics.technion.ac.il>",
  "eventId": "GRB 171205A"
}