Gamma-ray Burst 980515

The Gamma-Ray Burst was detected by BeppoSAX GRBM on 1998 May 15, 17:00:10 UT. With the BeppoSAX WFC the location could be deduced with an 5 arcmin error circle centered at R.A. = 319.518, Decl. = -67.249 degrees (2000.0).
A follow-up observation with the BeppoSAX NFI instruments was initiated within 9 hrs.
A ROSAT TOO observation is not possible due to Sun angle constraints.
(All information courtesy of the instrument teams.)

Previous IAU Circulars

• IAUC 6909 NFI detection of 1SAX J2116.8-6712
• IAUC 6910 refined WFC position

• BeppoSAX GRB MAIL N. 98/13
  A GRB (GB980515) was observed by the BeppoSAX GRBM at about 17:00:10 UT of May 15. The event was detected by one of the WFC (WFC2), with preliminary position:

   R.A. =  319.25
  Decl. = -67.238
  

  with an error radius of 5'. A BeppoSAX follow up with the NFI is being planned.
• GCN notice #72
  Luigi Piro and Marco Feroci on behalf of the BeppoSAX team report: A GRB (GB980515) was observed by the BeppoSAX GRBM at about 17:00:10 UT of May 15. The event was detected by one of the WFC (WFC2). The updated WFC position is:

     RA(2000)=319.518
     Dec(2000)=-67.249
  

  The error radius is still of 5'. A further refinement of the WFC position should be available next Monday. The BeppoSAX follow-up with the NFI should start around 2 AM UT of May 16.
• GCN notice #73
  Marco Feroci and Jean in 't Zand on behalf of the BeppoSAX Mission Scientist report: The BeppoSAX-WFC position of GRB980515 has been revised using the Final Observing Tape. The revised burst position is:

  R.A. = 319.3527 (21h 17m 25s), Decl. = -67.2550 (-67o 15' 18") Eq. 2000.0
  

  We give an error radius of 4 arcmin. This is somewhat larger than the usual 3 arcmin because of low statistics of the burst. This position lies at 3.8 arcmin from the latest distributed position, and 2.6 arcmin from the first distributed position.
• BeppoSAX GRB MAIL N. 98/15
  A previously unknown faint X-ray source has been found by MECS during the follow up observation starting about 10 hrs after the GRB. Position is:

    R.A.(2000)= 21h 16m49s.5
    Dec.(2000)= -67o 11'48".6  
  

  with an error radius of 1'.5
• GCN notice #77
  Marco Feroci on behalf of the BeppoSAX team reports the following submission to the IAU Circulars: GRB 980515 M. Feroci and L. Piro, Istituto Astrofisica Spaziale, CNR, Rome; M.R. Daniele, G. Gennaro, S. Rebecchi, and G. Celidonio, BeppoSAX Science Operation Center, Rome; L.A. Antonelli, BeppoSAX Science Data Center, Rome; and J. Heise, Space Research Organization of the Netherlands, Utrecht, report: "The BeppoSAX Wide Field Camera error box of GRB 980515 was observed with the BeppoSAX Narrow Field Instruments (NFI) starting on May 16.1178 UT (10 hr after the burst). A previously unknown x-ray source, 1SAX J2116.8-6712, was detected by the MECS (units 2 and 3) at R.A. = 21h16m49s, Decl. = -67o11'.8 (equinox 2000.0; preliminary error radius 1'.5 due to the poor statistical quality). This position is 4'.9 from the centroid of the WFC position (GCN #73). The source 1SAX J2116.8-6712 exhibits a moderate variability over the two-day NFI observation. There is no clear evidence for a monotonic decaying behaviour. The average countrate was 0.0026 +/- 0.0006 count/s (2-10 keV) in the two MECS units, corresponding to (1.6 +/- 0.4) x 10E-13 erg cmE-2 sE-1 (assuming a Crab-like energy spectrum). At this time 1SAX J2116.8-6712 is the only candidate as the x-ray afterglow of GRB 980515".