{
  "bibcode": "2009GCN..9436....1K",
  "body": "D. A. Kann, U. Laux and B. Stecklum (TLS Tautenburg) report:\n\nWe observed the optical afterglow (Xin et al., GCN 9431) of the Swift GRB \n090529 (Sakamoto et al., GCN 9430) with the 1.34m Schmidt telescope of the \nThueringer Landessternwarte Tautenburg, Germany. Observations began at \ntwilight, which, together with the setting moon, caused an elevated sky \nbackground. Airmass was low and conditions were excellent until clouds \ncame in during the last Rc image. We obtained 6 x 300 sec dithered images \nin the Ic band and 3 x 600 sec images in the Rc band. The afterglow is \nvery faintly visible on several Ic frames, clearly visible on the first \ntwo Rc frames and hardly visible on the last Rc frame.\n\nUsing the USNOB1.0 catalog as a reference, we derive the following \nposition (J2000) for the afterglow:\n\nRA = 14:09:52.53\nDec. = +24:27:32.77\n\nwith an error of 0\".5. This position lies 0\".7 from the UVOT position \n(Schady et al., GCN 9435), in full agreement with it.\n\nWe find several sources of roughly similar magnitude within 10\" of the \nafterglow. These may slightly affect the photometry.\n\nTo calibrate, we use the isolated star with USNO catalog # 1144-0210566 at \nposition\n\nRA = 14:09:47.50\nDec. = +24:27:44.5\n\nwhich has R2 = 18.32 mag and I = 17.54 mag. (Note that it is 0.54 mag \nbrighter in R1.)\n\nWe derive the following magnitudes 0.3 days after the GRB:\n\ntime (d)\tMag\tdMag\tExposure\tFilter\n\n0.287871\t20.98\t0.13\t6 x 300\t\tIc\n0.304668\t21.39\t0.12\t1 x 600\t\tRc\n0.312191\t21.40\t0.12\t1 x 600\t\tRc\n0.319703\t21.47\t0.35\t1 x 600\t\tRc\n\nCompared to the magnitude found by Xin et al., GCN 9431, this indicates \nthe afterglow has faded by two magnitudes. The normal Rc - Ic color as \nwell as the confirmation by Swift UVOT of a rising afterglow (Schady et \nal., GCN 9435) implies that it is not overly reddened, an alternate \nexplanation by Holland et al., GCN 9432.\n\nNo further observations are planned.\n\nThis message may be cited.",
  "circularId": 9436,
  "createdOn": 1243642332000,
  "email": "kann@tls-tautenburg.de",
  "subject": "GRB 090529: TLS Afterglow Observations",
  "submitter": "Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>",
  "eventId": "GRB 090529"
}