{
  "bibcode": "1999GCN...301....1V",
  "body": "P.M. Vreeswijk and E. Rol (University of Amsterdam) report on behalf\nof the Amsterdam/Huntsville GRB optical follow-up team:\n\nWe measured the object at RA 11:54:57.80, Decl -26:43:03.8 (J2000)\nreported by Vrba et al. to be variable (GCN #300) in our Harris-R band\nimages, taken with the WIYN telescope at May 8.18 UT. We find R =\n22.21 +/- 0.15 using an aperture size which is twice the seeing disk\nof 1.05\"). Our measurement was taken at about the same time as where\nVrba et al. report Rc > about 23. The data were calibrated using the\nRUBIN 149 field of the Landolt catalog (Landolt et al. 1992, 104,\n340). The value we find for the reference star at RA 11:54:51.6, Decl\n-26:43:4.09 (J2000), R = 16.1 +/- 0.1 is in good agreement with the\nVrba et al. calibration for this star: R = 16.11.\n\nBased on our result we believe the object is constant, but we urge\nmore observations to confirm/reject the variable nature of this\nobject.\n\nThis message is citeable.",
  "circularId": 301,
  "createdOn": 926184790000,
  "email": "pmv@astro.uva.nl",
  "subject": "GRB 990506 optical observations",
  "submitter": "Paul Vreeswijk at U of Amsterdam  <pmv@astro.uva.nl>",
  "eventId": "GRB 990506"
}