{
  "bibcode": "2008GCN..7705....1K",
  "body": "D. A. Kann, C. Hoegner, R. Filgas and S. Klose (TLS Tautenburg) report:\n\nWe observed again the location of the candidate afterglow (Kann et al., \nGCN 7701) of the AGILE GRB 080507 (Lapshov et al., GCN 7697), which was \nalso detected as a bright X-ray source (Mangano et al., GCN 7699). We \nobtained 20 x 180 sec images in the R band under excellent atmospheric \nconditions but with elevated sky background due to twilight and the waxing \nmoon. The resulting stacked image is roughly half a magnitude deeper than \nthe image from the first epoch (23.5 vs. 23, respectively).\n\nWe find that the candidate afterglow has significantly faded over the \ncourse of a day. Using the same comparison star as Kann et al. (GCN 7701), \nwe find:\n\ntime (days)\tRc\tdRc\n\n2.5578\t\t22.69\t0.15\n\nWe also use SExtractor (Bertin & Arnouts 1996) to derive magnitudes, and \nfind Rc = 21.95 +/- 0.14 and Rc = 22.65 +/- 0.20 in the first and second \nepoch, respectively, in accordance with our other results.\n\nThis fading behaviour is in contrast to the plateau phase or even rising \nbehaviour reported from UVOT White images (Breeveld & Baumgartner, GCN \n7702), which may imply a non-monotonic light curve evolution.\n\nWith the clear detection of fading, we consider the identification of this \nsource as the optical afterglow of GRB 080507 as secure.\n\nFinally, we note that GRB 080507 was also detected by INTEGRAL SPI-ACS, \nshowing a flat-topped structure, with possible multiple peaks, of 40 \nseconds duration, in full agreement with the AGILE report (Lapshov et al., \nGCN 7697). The public light curve can be found here:\n\nhttp://isdc.unige.ch/cgi-bin/cgiwrap/~beck/ibas/spiacs/ibas_acs_web.cgi/\n?trigger=2008-05-07T07-44-58.8545-18523-00007-0\n\nThis message may be cited.",
  "circularId": 7705,
  "createdOn": 1210376920000,
  "email": "kann@tls-tautenburg.de",
  "subject": "GRB 080507: E Pur Si Muove!",
  "submitter": "Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>",
  "eventId": "GRB 080507"
}