{
  "body": "K.L. Page, P.A. Evans (U. Leicester) and C.A. Gronwall (PSU) report on\nbehalf of the Swift-XRT Team\n\nOn 2025 March 27 at 21:35 UT, Swift began a Target-of-Opportunity\nobservation of the SVOM-discovered burst GRB 250327B (GCN Circ. 39888).\n750 s of data were collected, starting 1.7 ks after the SVOM/ECLAIRs\ntrigger. A bright, fading X-ray source was found, at a position of RA, Dec\n= 176.77890, 29.83953, which is equivalent to\n\nRA (J2000) =  11h 47m 06.94s\nDec (J2000) = +29d 50' 22.3\"\n\nwith an uncertainty of 3.5 arcseconds (radius, 90% confidence). This is\nconsistent with the optical afterglow (GCN Circs. 39889, 39890, 39891,\n39894), with a measured redshift of 3.035 (GCN Circ. 39893).\n\nThe light curve can be modelled with a power-law decay with a decay index\nof alpha=1.20 (+0.73, -0.66).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.47 (+/- 0.09) and the Galactic\ncolumn density of 1.76 x 10^20 cm^-2 (Willingale et al. 2013).\n\nIf the light curve continues to decay with a power-law decay index of\n1.20, the count rate at T+24 hours will be 0.048 count s^-1\n\n\n",
  "circularId": 39895,
  "bibcode": "2025GCN.39895....1P",
  "subject": "GRB 250327B: Swift-XRT detection of the X-ray afterglow",
  "eventId": "GRB 250327B",
  "submittedHow": "email",
  "submitter": "K.L. Page at U Leicester <klp5@leicester.ac.uk>",
  "createdOn": 1743133157603
}