Gamma-ray Burst 001018

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN notice #853
  K. Hurley, on behalf of the Ulysses GRB team, T. Cline, on behalf of the Konus-Wind and NEAR GRB teams, and E. Mazets, and S. Golenetskii, on behalf of the KONUS-WIND GRB team, report:
  Ulysses, NEAR, and KONUS-WIND observed this GRB at 61114 seconds. As observed by Ulysses, it had a duration of approximately 31. seconds, a 25-100 keV fluence of approximately 1.2E-05 erg/cm2, and a peak flux of approximately 5.0E-01 erg/cm2 s over .50 seconds We have triangulated it to a preliminary, 3 sigma error whose approximate area is 15. sq. arcmin. and whose coordinates are:
  

          RA(2000)                           DEC(2000)
   ERROR BOX CENTER:  13 h 14 m 10.27 s     11 o 48 '  31.75 " 
   ERROR BOX CORNER 1: 13 h 14 m 13.68 s     11 o 49 '  31.43 " 
   ERROR BOX CORNER 2: 13 h 13 m 50.40 s     11 o 51 '  29.08 " 
   ERROR BOX CORNER 3: 13 h 14 m 30.12 s     11 o 45 '  34.18 " 
   ERROR BOX CORNER 4: 13 h 14 m  6.85 s     11 o 47 '  32.06 " 
  

  This error box may be improved
• GCN notice #854
  In GCN #853, and in the socket message IPN #8, the peak flux should have read 5.0E-6 erg/cm^2 s.
• GCN notice #856
  S. Sinha, P. Sreekumar, K. Kasturirangan, on behalf of SROSS C-2 (INDIAN GRB EXPERIMENT) team report:
  SROSS C-2 observed this burst at 61116.784 s UT (this time may contain small systematic errors). As observed by SROSS C-2, it had a duration (T90) of 1.63 +- 0.05 secs, a 20-1024 keV fluence (not corrected for the sec(theta) factor since we donot know the direction) equal to 1.15 X 10 -5 ergs cm-2. The peak flux (256 ms) in 20-100 keV band is equal to 20.09 photons cm-2 sec-1 and the peak flux (256 ms) in 100-1024 keV band is equal to 12.15 photons cm-2 sec-1. The Hardness Ratio (at the peak of the burst) is equal to 0.32 +- 0.05. Our Hardness Ratio is defined as [counts(100-1024 keV)/counts(20-100 keV)]. For 21 SROSS C-2 GRBs that are common with BATSE we find a mean Hardness Ratio of 0.97 +- 0.08 and the standard deviation of the hardness distribution is equal to 0.37.
  Srikanta Sinha, on behalf of the SROSS C-2 (INDIAN GRB EXPERIMENT TEAM) at the Technical Physics Division, ISRO Satellite Center, Bangalore-560 017, INDIA.
• GCN notice #857
  G. B. Taylor (NRAO) reports on behalf of a larger collaboration:
  We imaged the IPN error box of GRB001018 (GCN #853) with the VLA at 8.46 GHz, starting on Oct. 19.88 UT. A second observation was obtained starting on Oct. 20.76 UT. One unresolved radio source (size < 0.25 arcsec) is detected within the IPN error box at (J2000) R.A.= 13 14 12.385, Dec. =11 48 57.90 with an error of approximately 50 mas in each coordinate. The VLA flux density at 8.46 GHz was 258 +/- 65 microJy on Oct 19.88, and 405 +/- 50 microJy on Oct 20.76. No source is detected in the NRAO VLA Sky Survey (NVSS; Condon et al. 1998, AJ, 115, 1693) above their flux limit of 1 mJy at 1.4 GHz. Based on its compact and possibly variable nature we suggest that the source VLA J1314+1148 could be the radio afterglow from G001018. Further observations with the VLA are planned.
• GCN notice #915
  Optical observations of GRB 001018 with JCAM
  J. S. Bloom, A. Diercks, S. R. Kulkarni, F. A. Harrison, (Caltech), B. B. Behr (U. Texas), J. C. Clemens (UNC) report on behalf of the larger GRB-NRAO-CARA GRB collaboration:
  "On 18 December 2000 UT, J. Bloom and D. Reichart observed the field of GRB 001018 (Hurley et al., GCN #853) near the transient radio position reported by Taylor et al. (GCN #857) on the Palomar 200-inch telescope during a commissioning run of the Jacobs Camera (JCAM), a dual-CCD imager designed primarily for rapid follow-up of GRB afterglow. The plate scale of JCAM is 0.38 arcsec/pixel and the field-of-view is 3.2 x 3.2 arcmin^2.
  We observed the GRB field simultaneously in R- and B-band for a total of 2700s. An astrometric plate solution was obtained using 10 (11) ties stars common to both the USNO-A2.0 catalogue and the R- (B-) band summed image. The total absolute astrometric uncertainty in the R-band plate solution was 0.32", 0.27" in RA and Dec. Unfortunately, the seeing (2.8 arcsec FWHM in R-band) was very poor at Palomar on 18 December and there was significant extinction due to cirrus. At the position of Taylor's radio transient there were no detected objects to R~22.7 mag (5-sigma); the photometric zeropoint was estimated using the USNO stars in the field."
  The R and B finding chart images of the may be obtained at: http://www.astro.caltech.edu/~jsb/GRB/grb001018/
  For further information on JCAM, please see: http://www.astro.caltech.edu/~jsb/Jcam
  This message may be cited.
• GCN notice #918
  Optical Observations of GRB 001018 at Keck
  J. S. Bloom, S. G. Djorgovski, F. A. Harrison, P. Mao (Caltech), and D. Stern (JPL) report on behalf of the larger Caltech-NRAO-CARA GRB Collaboration:
  "We observed the field of GRB 001018 (Hurley et al., GCN #853) with the Keck Telescopes on the nights of 29 December 2000 UT and 1 January 2001 UT with LRIS (Oke et al. 1995) and ESI (Sheinis et al. 2000), respectively. About 1 arcsec from the position of the radio transient reported by Taylor et al. (GCN #857), we find a faint compact source, likely an unresolved galaxy.
  An astrometric plate solution was obtained using 16 USNO A2.0 stars in common with a 20s R-band exposure with LRIS. The total r.m.s errors on the resulting tie to the ICRS were 0.31", 0.27" (ra,dec), including the systematic uncertainties in the USNO A2.0 catalogue described by Deutsch 1998. Including the uncertainties in the radio position and the nearby galaxy position, the centroid of the galaxy is 0.46" +/- 0.32" E, 0.89" +/- 0.27" N of Taylor's radio transient. Given the proximity to the radio transient, this galaxy may be related to the radio transient.
  We obtained photometric zeropoints using the Landolt standard star fields of PG1047+003 (R-band) and SA 104 (I-band). For the galaxy, we find that I=24.03 +/- 0.10 mag (1 Jan 01 UT) and R=24.60 +/- 0.09 mag. This detection is consistent with the upper limit placed by Bloom et al. (GCN #915). For comparison, we find for stars A (ra=13:14:09.9, dec=+11:48:56, J2000) and B (ra=13:14:09.4, dec=+11:48:23, J2000) that I(A) = 18.42 +/- 0.03 mag, R(A) = 18.54 +/- 0.03 mag, I(B) = 18.82 +/- 0.03 mag, and R(B) = 19.91 +/- 0.03 mag."
  This message may be cited.