Gamma-ray Burst 091015

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #10025
  C. Ferrigno (ISDC, Versoix/IAAT, Tuebingen), D.Gotz (CEA-Saclay), S.Mereghetti, A.Paizis (IASF-Milano), E. Bozzo, M. Beck (ISDC, Versoix), and J.Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report:
  A faint long GRB with duration of about 100 s has been detected by IBAS in IBIS/ISGRI data at 23:00:17 UTC on August 15th. No automatic alert has been issued because the trigger was at low significance.
  Interactive off-line analysis has allowed to confirm the GRB nature of the trigger.
  The refined coordinates (J2000) are:
  RA: 306.13 [degrees] DEC: -6.17 [degrees]
  with an uncertainty of 3 arcmin (90% c.l.).
  The soft spectrum of the GRB (only detected in the 20-40 keV energy range) and the long, slowly rising light curve may indicate a highly redshifted burst. Follow-up observations at other wavelengths are encouraged.
  The light curve of the GRB will be posted at http://ibas.iasf-milano.inaf.it/IBAS_Results.html
  This message can be cited.
• GCN Circular #10026
  D. Gotz (CEA Saclay) on behalf of the IBAS Team reports:
  GCN number 10025 contains a mistake: the burst name is 091015 since it has been detected on October 15th, and not on August 15th as stated ih the GCN.
• GCN Circular #10029
  R. Gumerov, A. Nemtinov, I. Bikmaev, N. Sakhibullin (KSU/AST), R. Burenin, M. Pavlinsky, R. Sunyaev (IKI), M. Parmaksizoglu, I. Khamitov, Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)
  report:
  The optical afterglow of GRB 091015 (Ferrigno et al., GCN 10025, Gotz et al., GCN 10026) was observed with Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National Observatory, Turkey) in partially cloudy conditions. We obtained a serie of 60s images in R centered at October 16, 17:40 UT, i.e. 0.76 days after the burst. The limiting magnitude in combined image is estimated as R=~22. We do not detect any new optical object as compared to DSS II red plate.
• GCN Circular #10035
  A. LaCluyze, D. Reichart, K. Ivarsen, J. Haislip, R. Egger, A. Foster, J. Moore, A. Oza, M. Schubel, J. Styblova, A. Trotter, J. A. Crain, and M. Nysewander report:
  Skynet observed ~90% of the INTEGRAL/IBAS localization of GRB 091015 (Ferrigno et al., GCN 10025; Gotz, GCN 10026) with one of the 16" PROMPT telescopes at CTIO beginning 25.3 hours after the the trigger in z.
  We do not detect any uncatalogued sources. Stacking only images that increase the limiting magnitude yields:

  mean                                                  1-sig.  1-sig.
  time                             3-sig.               sys.    stat.
  since                            lim.    cal.         cal.    cal.
  trig.  tel.      exp.      fil.  mag.    stars*       unc.    unc.
  (h)              (# x s)                              (mag)   (mag)
  
  27.1   PROMPT-5  144 x 80  z*    21.2    319 USNO B1  0.313   0.000
  

  * Calibrated to I