{
  "circularId": 42333,
  "submitter": "leavittob@gmail.com",
  "bibcode": "2025GCN.42333....1P",
  "format": "text/plain",
  "subject": "GRB 251013C: Leavitt Observatory optical photometry",
  "createdOn": 1760734604505,
  "body": "E. Pavoni, L. Moretti (Leavitt Observatory, Italy)\n\nMembers of:\nGRB/UAI - Gamma Ray Burst Section of Unione Astrofili Italiani\n\nIn a large collaboration with:\nM.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy), report:\n\nWe performed a follow-up observation of the field of GRB 251013C (Fermi GBM team, GCN 42221; Rakotondrainibe et al., GCN 42222) using our 250mm f/8 Ritchey-Chrétien telescope (Leavitt Observatory, Manciano, Italy).\n\nObservations began on 2025-10-13 at 19:09:11 UT (≈ 1.5 hours after the trigger) and ended at 22:19:55 UT. A series of images in Rc and Ic filter (Johnson-Cousins system) was obtained under good weather conditions.\n\nWe clearly detected a bright afterglow positionally consistent with the source reported in previous circulars. The OT coordinates are:\n\nRA (J2000) =  23:03:20.55\nDec(J2000) = -00:12:35.12\n(±2 arcsec on both axes)\n\nPhotometry was performed using nearby stars from the Pan-STARRS catalog (magnitudes converted using Lupton (2005) equations) and analysed with AstroImageJ (2017AJ....153...77C). The following magnitudes were measured (not corrected for Galactic extinction):\n\nHJD at mid-exposure\t\tFilter\t\tMag.   \tMag. err.\n2460962.30386029\t\tRc\t\t15.38\t0.01\n2460962.30725948\t\tRc\t\t15.51\t0.01\n2460962.30996796\t\tRc\t\t15.67\t0.01\n2460962.31258558\t\tRc\t\t15.73\t0.02\n2460962.31556121\t\tRc\t\t15.74\t0.02\n2460962.31806558\t\tRc\t\t15.76\t0.02\n2460962.32017580\t\tRc\t\t15.86\t0.02\n2460962.32228375\t\tRc\t\t15.84\t0.02\n2460962.32439216\t\tRc\t\t15.84\t0.02\n2460962.32650057\t\tRc\t\t15.89\t0.02\n2460962.32860895\t\tRc\t\t15.90\t0.02\n2460962.33071795\t\tRc\t\t15.92\t0.02\n2460962.33282552\t\tRc\t\t15.97\t0.02\n2460962.33493454\t\tRc\t\t15.96\t0.02\n2460962.33704239\t\tRc\t\t16.04\t0.02\n2460962.33915074\t\tRc\t\t16.12\t0.02\n2460962.34126105\t\tRc\t\t16.12\t0.02\n2460962.34337272\t\tRc\t\t16.19\t0.02\n2460962.34548188\t\tRc\t\t16.27\t0.02\n2460962.34759218\t\tRc\t\t16.29\t0.02\n2460962.35500912\t\tRc\t\t16.33\t0.02\n2460962.35926398\t\tRc\t\t16.34\t0.02\n2460962.36351931\t\tRc\t\t16.37\t0.02\n2460962.36777694\t\tRc\t\t16.41\t0.02\n2460962.37203488\t\tRc\t\t16.56\t0.03\n2460962.37629036\t\tRc\t\t16.46\t0.03\n2460962.38920934\t\tRc\t\t16.64\t0.03\n2460962.39346447\t\tRc\t\t16.54\t0.03\n2460962.39772065\t\tRc\t\t16.69\t0.03\n2460962.40623373\t\tRc\t\t16.80\t0.04\n2460962.41049247\t\tRc\t\t16.75\t0.03\n2460962.41474858\t\tRc\t\t16.93\t0.04\n2460962.41900117\t\tRc\t\t16.82\t0.04\n2460962.42325452\t\tRc\t\t16.72\t0.04\n2460962.42750818\t\tRc\t\t17.11\t0.05\n\n2460962.35287059\t\tIc\t\t15.94\t0.03\n2460962.35712512\t\tIc\t\t15.95\t0.03\n2460962.36138024\t\tIc\t\t15.92\t0.03\n2460962.36563799\t\tIc\t\t15.86\t0.03\n2460962.36989563\t\tIc\t\t16.05\t0.04\n2460962.37415044\t\tIc\t\t16.25\t0.04\n2460962.38706915\t\tIc\t\t16.14\t0.04\n2460962.39132719\t\tIc\t\t16.19\t0.04\n2460962.39558282\t\tIc\t\t16.33\t0.05\n2460962.39983877\t\tIc\t\t16.23\t0.05\n2460962.40409469\t\tIc\t\t16.37\t0.05\n2460962.40835283\t\tIc\t\t16.40\t0.05\n2460962.41261135\t\tIc\t\t16.43\t0.06\n2460962.41686396\t\tIc\t\t16.24\t0.05\n2460962.42111700\t\tIc\t\t16.42\t0.06\n2460962.42537095\t\tIc\t\t16.49\t0.06\n2460962.42997457\t\tIc\t\t16.68\t0.07\n2460962.43422909\t\tIc\t\t16.63\t0.07\n\n\nThis message may be cited.\n\nReference:\nhttps://leavittobservatory.altervista.org",
  "submittedHow": "web",
  "eventId": "GRB 251013C"
}