{
  "bibcode": "2006GCN..5187....1K",
  "body": "D. A. Kann (TLS Tautenburg) and C. C. Thoene (DARK Cosmology Center)\nreport:\n\n\nGathering further data from the GCN (Khamitov et al., GCN 5183, 5186,\nBaliyan et al., GCN 5185) in addition to those referenced in Kann &\nHoegner (GCN 5182), we perform fits to the R afterglow light curve.\n\nA single power law fit to all data beyond 6000 seconds yields alpha = 1.04\n+/- 0.01, but the late-time data beyond two days lie significantly beneath\nthe fit.\n\nA broken power law gives a better fit, with alpha_1 = 0.98 +/- 0.10,\nalpha_2 = 2.06 +/- 0.13, and break time t_b = 1.76 +/- 0.1 days. The break\nsmoothness parameter n is fixed to 10.\nStill, the fit is not acceptable, with strong deviations around 0.5 days.\n\nFitting separate parts of the light curve, we find a better fit with a\ndouble broken power law. The first part (0.19 to 1.1 days) is described by\nalpha_1 = 1.35 +/- 0.07, alpha_2 = 0.85 +/- 0.08 and t_b = 0.44 +/- 0.08\ndays, n = -10 fixed. The fit is marginally acceptable, with\ndeviations due to scatter (different zero points and comparison stars).\n\nThe second part (0.53 days to the end) is described by alpha_1 = 0.76 +/-\n0.04, alpha_2 = 1.87 +/- 0.07 and t_b = 1.42 +/- 0.08 days, n = 10 fixed.\nThis fit is acceptable. Alpha_2 of the first part and alpha_1 of the\nsecond part are identical within errors, as expected. We note that the\nextension of this last fit to early times is consistent with the first\nROTSE data point (Rykoff et al., GCN 5166) and marginally consisten with\nthe very early Watcher data (French & Jelinek, GCN 5165).\n\nThis strengthens the picture that the break first described by Thoene et\nal. (GCN 5179) is the jet break. The post-break decay is relatively\nsmooth.\n\nWe caution that these fits do not include the dense data set presented by\nHalpern, Armstrong & Mirabal (GCN 5176) and the optical flare they\ndetected. Similar to early fits of GRB 030329 presented in the GCN, these fits may\nbe the result of inhomogenous coverage of a highly variable light curve.\n\nFurther deep monitoring is encouraged.\n\nThe plots for the double broken power law fits can be found at\nwww.astro.ku.dk/~cthoene",
  "circularId": 5187,
  "createdOn": 1149007418000,
  "email": "cthoene@astro.ku.dk",
  "subject": "GRB060526: afterglow fitting and probable jet break",
  "submitter": "Christina Thoene at Niels Bohr Institute,DARK Cosmo Ctr  <cthoene@astro.ku.dk>",
  "eventId": "GRB 060526"
}