Gamma-ray Burst 090306B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 07 Mar 09 15:27:44 UT
  NOTICE_TYPE:     Swift-BAT Slew GRB Position
  ID_NUM:          26
  GRB_RA:          231.200d {+15h 24m 48s} (J2000),
                   231.322d {+15h 25m 17s} (current),
                   230.533d {+15h 22m 08s} (1950)
  GRB_DEC:          -6.960d {-06d 57' 35"} (J2000),
                    -6.992d {-06d 59' 30"} (current),
                    -6.784d {-06d 47' 02"} (1950)
  GRB_ERROR:       0.88 [arcmin radius, statistical only]
  GRB_INTEN:       819440 [cnts]    Image_Peak=0 [image_cnts]
  TRIGGER_DUR:     43.400 [sec] 
  TRIGGER_INDEX:   10     Criteria: S(15-50) > 4.0 sigma  AND  H(50-150) > 4.0 sigma
  ENERGY_RANGE:    15-150 keV
  BKG_INTEN:       0 [cnts]
  BKG_TIME:        0.00 SOD {00:00:00.00} UT
  BKG_DUR:         0 [sec]
  GRB_DATE:        14896 TJD;    65 DOY;   09/03/06
  GRB_TIME:        83297.19 SOD {23:08:17.19} UT
  SOLN_STATUS:     0x13
  RATE_SIGNIF:     0.00 [sigma]
  IMAGE_SIGNIF:    0.00 [sigma]
  SUN_POSTN:       348.22d {+23h 12m 52s}   -5.06d {-05d 03' 31"}
  SUN_DIST:        115.88 [deg]   Sun_angle= 7.8 [hr] (West of Sun)
  MOON_POSTN:      123.76d {+08h 15m 02s}  +20.39d {+20d 23' 14"}
  MOON_DIST:       108.86 [deg]
  MOON_ILLUM:      85 [%]
  GAL_COORDS:      356.00, 39.62 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      230.63, 11.33 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT Slew GRB Coordinates.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        Extremely high confidence of reality (gold-plated).  
  COMMENTS:        This Notice was ground-processed from flight-data.  
  COMMENTS:          
  

• red DSS finding chart ps-file
  
  
• GCN Circular #8944
  A. Copete, J. Grindlay (Harvard) S. Barthelmy, C. Markwardt, N. Gehrels (NASA/GSFC) We report the detection of a bright GRB by the BAT Slew Survey (BATSS) in the slew that started at 23:07:02 and lasted 66 sec. The ground- calculated position is RA, Dec = 231.204, -6.958 deg, which is

  RA (J2000) = 15h 24m 49s
  Dec(J2000) = -06d 57' 29"
  

  with an uncertainty of 2.87 arcmin (90% confidence, including systematics). The detection was triggered by simultaneous independent detections of 35.6 sigma and 20.2 sigma from imaging in the 15-50 keV and 50-150 keV energy bands, respectively. The burst mask-tagged lightcurve lightcurve in the 15-150 keV band shows a strong and broad emission peak starting at T+21sec, lasting 29 sec, and peaking twice at T+25sec and T+30sec. T90 = 20.4sec and T50 = 8.0sec.
  The time-averaged spectrum over the 55 sec exposure time of the source is best fit by a power law with an exponential cutoff, with photon index 1.02 and high-energy cut at 133 keV. The fluence in the 15-150 keV band is 3.1 x 10^-6 erg/cm^2, and and the peak 1-sec flux is 2.5 10^-7 erg/cm^2/sec at T+30sec. A follow-up Swift ToO observation for this burst has been scheduled.
• GCN Circular #8947
  P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
  Swift-XRT observed the field of the BAT Slew Survey burst GRB 090306B (Copete et al. GCN Circ. 8944) for 5.8 ks, from T0+67 ks to T0+81 ks. The data were entirely in PC mode.
  A single, faint source is found in the BATSS error circle, with a position RA,Dec = 231.2083, -6.9682 which is equivalent to:

  RA (J2000)  = 15 24 49.99
  Dec (J2000) = -06 58 05.6
  

  with an uncertainty of 4.0 arcsec (radius, 90% confidence).
  We currently have only 16 counts from this source, at a count rate of 3.5 (+/- 0.9) e-3 counts s-1, and are unable to ascertain whether it is fading.
  Further observations, to verify the nature of this source, are planned.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #8958
  A. C. Updike (Clemson University), C. Clemens, J. Greiner and P. Afonso (MPE Garching) report on behalf of the GROND team:
  We observed the field of GRB 090306B (BATSS, Copete et al., GCN #8944) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile).
  Observations started at 04:34 UT on March 8th, about 29.5 hours after the GRB trigger, and lasted 45 min.
  We do not detect a source within the Swift-XRT error circle reported by Evans (GCN #8947) down to (all in AB system)

  g' > 23.2,
  r' > 23.6,
  i' > 23.3,
  z' > 23.0,
  J > 21.7,
  H > 21.0 and
  K > 20.1.
  

  The given limits are derived based on calibrating the images against GROND zeropoints and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.11 in the direction of the burst (Schlegel et al. 1998).
• GCN Circular #8968
  V. Beckmann, M. Beck, C. Ferrigno, N. Produit, V. Savchenko (ISDC), J. Borkowski (CAMK/Torun), D. Gotz (CEA/Saclay), S. Mereghetti (INAF/IASF-Milano), A. von Kienlin (MPE) report on behalf of the INTEGRAL SPI-ACS GRB team:
  GRB 090306B, detected in Swift/BAT slew data (Copete et al. GCN 8944), has been independently detected by the SPI Anti-Coincidence System (ACS) on-board INTEGRAL. The SPI-ACS light curve shows the peak of the burst at 2009-03-06T23:07:21.9 with a maximum count-rate of ~390 counts/50msec. The duration of the GRB is about 14 seconds.
  The SPI-ACS light curves are available (both as images and data files) at http://isdc.unige.ch/Soft/ibas/ibas_acs_web.cgi
  The light curves, binned at 50 ms, are derived from 91 independent detectors with different lower energy thresholds (mainly between 50 keV and 150 keV) and an upper threshold at about 100 MeV. The ACS response varies as a function of the GRB incident angle. For these reasons we caution that the count rates cannot be easily translated into physical flux units.
• GCN Circular #8987
  P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
  Swift has performed follow-up observations of the BAT Slew Survey GRB 090306B (Copete et al, GCN Circ. 8944), gathering 4 ks of data in the interval T0+484 ks to T0+555 ks. The X-ray source reported by Evans et al. (GCN Circ 8947) is no longer detected, with a 3-sigma upper limit of 1.9e-3 counts/sec. We thus confirm that it was the afterglow of GRB 090306B.
  This circular is an official product of the Swift-XRT team.
• GCN Report 201.1
  GCN_Report 201.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_201_1.pdf by P.A. Evans at U.Leicester titled: "Final Swift Observations of GRB 090306B"