Gamma-ray Burst 990627

On June 27, 1999 a GRB was detected by the BeppoSAX GRBM and WFC instruments. Follow-up observations show a fading X-ray source, the probable X-ray afterglow of a GRB.

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• IAUC 7211 BeppoSAX WFC discovery
• IAUC 7213 fading X-ray source 1SAX J0148.5-7704

• BeppoSAX GRB alert n. 99/10
  On Jun.27, 5:00:51 UT a GRB (GRB990627) was detected simultaneously by the GRBM and WFC of BeppoSAX.
  Preliminary coordinates from WFC are:

  R.A.(2000)= 26.895
  DEC(2000)= -77.092
  

  with an error radius of about 5'
  A follow-on with NFI is being planned
• BeppoSAX GRB alert n. 99/11 = GCN notice #356
  A GRB (GRB 990627) was detected by the GRBM and WFC of BeppoSAX on June 27, at 05:00:51 U.T.
  Final coordinates from WFC are:

  R.A.(2000)=27.1055
  DEC(2000)=-77.0883
  

  The error radius is 3'.
• GCN notice #357:
  R. Subrahmanyan (CSIRO), M. Wieringa (CSIRO), D. A. Frail (NRAO) and S. R. Kulkarni (Caltech) report on behalf of a larger collaboration:
  We obtained an 11 hour integration with the Australia Telescope Compact Array (ATCA) centered on June 28.67 UT at 4.8 GHz (including 3 hours at 4.9 GHz), and an 8 hour integration centered on June 28.76 UT at 8.6 GHz. The ATCA was pointed at the BeppoSAX WFC position of GRB 990627 as given by Gandolfi (GCN 356).
  Within the 3-arcmin WFC error circle there are four 6 cm sources above 5 sigma. We report these positions for the purpose of enabling observations at other wavelengths. We are making no claims at this time that any of these sources are the afterglow from GRB 990627. Further ATCA observations are planned to determine which, if any, of these sources are variable.

  AT J014829.6-770653: RA 01:48:29.65, DEC -77:06:53.3 (J2000)
  AT J014902.6-770517: RA 01:49:02.61, DEC -77:05:17.8 (J2000)
  AT J014832.6-770412: RA 01:48:32.60, DEC -77:04:12.0 (J2000)
  AT J014829.0-770253: RA 01:48:29.07, DEC -77:02:53.8 (J2000)
  

• GCN notice #358
  E. Rol (U. of Amsterdam), E. Palazzi, N. Masetti, E. Pian, F. Frontera (TeSRE, CNR, Bologna), T.J. Galama, P.M. Vreeswijk, J. van Paradijs (U. of Amsterdam), C. Kouveliotou (NASA/MSFC), G. Bakos, K. Sahu (STScI), P. Sackett (U. of Groningen), J. Menzies (SAAO), L. Nicastro (IFCAI, CNR, Palermo), E. Costa, (IAS, CNR, Rome), on behalf of a large collaboration including the PLANET Team and the BeppoSAX GRB optical follow-up Team, report:
  We have observed the error box of GRB990627 (Gandolfi, GCN #356) with the Sutherland 1.0m telescope (South Africa) in the R band on June 28.138-28.193, for a total exposure time of 4200 sec. Comparison of the summed image with the DSS (2nd Epoch Survey of the UK Schmidt; RG610 filter) does not show evidence of any new source above the DSS plate limit.
  Photometry linked to the USNO-A1.0 star at RA = 01h 48m 15s.61, Dec = -77o 04' 37".1 (J2000), which has R = 15.8, implies a 3-sigma magnitude limit of R ~ 21 for the sum image.
  We have also inspected the positions of the four radio sources found by Subrahmanyan et al. (GCN #357) in the GRB990627 error box. No object brighter than our limiting magitude is seen at any of them.
• GCN notice #359
  L.A. Antonelli, Osservatorio Astronomico di Roma, L. Nicastro, IFCAI, CNR, Palermo, M.R. Daniele, R. Ricci, BeppoSAX SDC, Telespazio, Roma M. Stornelli, BeppoSAX OCC, Dataspazio, Roma, A. Paolino, BeppoSAX SOC, Telespazio, Roma, E. Pian, E. Palazzi, ITESRE, CNR, G. Gandolfi and L. Piro IAS, CNR on behalf of the BeppoSAX Team report:
  The BeppoSAX NFIs observed the region of GRB990627 (GCN 356) from Jun 27.544 (8 hours after the BeppoSAX GRBM+WFC trigger) to Jun 28.864 UT for a total MECS on source exposure time of 29 ksec. A weak X-ray source (1SAX J0148.5-7704) lies within the 3' BeppoSAX WFC error-circle (GCN 356). Source position is RA= 01 48 25.4 DEC= -77 04 38, J2000, error radius 1' and is consistent with the radio source AT J014832.6-770412 reported by Subrahmanyan et al.(GCN 357). This source shows a fading behaviour strongly suggesting we detected the X-ray afterglow of GRB990627.