Gamma-ray Burst 990908

On September 8, 1999 a GRB was detected by the BeppoSAX GRBM and WFC instruments to 8 arcmin accuracy. No follow-up BeppoSAX observation was done, because the follow-up observation of GRB 990907 was still ongoing.

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none yet

• BeppoSAX GRB alert n. 99/26 and GCN notice #406
  A GRB (GB990908) was detected by the GRBM and WFC of BeppoSAX on Sep.8, around 00:18 UT. Preliminary coordinates from WFC are:

  R.A.(2000)=103.224
  DEC(2000)= -74.988
  

  The error radius is about 8'. Due to the in progress follow up of GRB990907, SAX will not repoint at this GRB.
• GCN notice #408
  Tim Axelrod, Jeremy Mould and Brian Schmidt (The Research School of Astronomy and Astrophysics, The Australian National University) report the following observations of GRB990907 and GRB990908. We have imaged the position of both GRB990907 and GRB990908 with the Mount Stromlo 50inch telescope + macho camera at multiple epochs in approximately 2.4" seeing. A differential image analysis of an area 21'x21' around the BeppoSAX position of GRB990907 (GCN 405) from two images taken 1999 Sep 8.56 and 1999 Sep 9.60 shows no variable sources with residuals brighter than a magnitude of m_v=20.3. A similar analysis of a 21'x21' field centered on the BeppoSAX position of GRB990908 (GCN 406) from images taken 1999 Sep 8.48 and 1999 Sep 9.59 shows a single variable stellar object (mag approx 18), fading by 0.3 magnitudes, present at both epochs, and present on the Digital Sky Survey (RA: 06:51:10.52 DEC: -75:02:17.3 J2000). This object is most likely a short period variable star within our own galaxy, but due to our poor seeing conditions, it is possible the host could be a compact galaxy, and is therefore worthy of further investigation. No other sources were seen with residuals brighter than m_v=20.3.