GRB090307A

This page lists all entries on GRB090307A in GRBweb

Summary IPN Swift GCN 8945 GCN 8946 GCN 8959 GCN 8974

Summary table
Variable Value Source
T0 3:46:37 UTC Swift
ra 244.9943° Swift
decl -28.6333° Swift
pos_error 2.72e-04° Swift
T90 22.0 s Swift
T90_start 3:46:37 UTC Swift
fluence 2.60e-07 erg/cm² Swift
T100 22.0 s
GBM_located False
mjd 54897.157372685186 Swift
IPN table
GRB_name GRB090307A
ra 244.9792°
decl -28.6500°
pos_error 5.00e-02°
Swift table
GRB_name GRB090307A
t_trigger 3:46:37 UTC
ra 244.9943°
decl -28.6333°
pos_error 2.72e-04°
T90 22.0 s
fluence 2.60e-07 erg/cm²
GCN 8945 table
GRB_name GRB090307A
GCN_number 8945
Detection_method Swift-BAT Det
ra 245.0070°
decl -28.6470°
Circular_text TITLE: GCN CIRCULAR NUMBER: 8945 SUBJECT: GRB 090307: Swift-BAT refined analysis of trigger 345551 DATE: 09/03/07 17:07:38 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), P. A. Evans (U Leicester), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+303 sec from recent telemetry downlinks, we report further analysis of posible GRB 090307 (trigger #345551) (Evans, et al., GCN Circ. 8943). The BAT ground-calculated position is RA, Dec = 245.007, -28.647 deg, which is RA(J2000) = 16h 20m 01.7s Dec(J2000) = -28d 38' 48.2" with an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment). We note that this position is based on a weak peak in the image domain (5.5 sigma). This is lower than our regular detections because this is a Subthreshold trigger. The partial coding was 87%. The mask-weighted light curve shows a weak pulse starting at ~T-7 sec and ending at ~T+20 sec. T90 (15-350 keV) is 22 +- 8 sec (estimated error including systematics). The time-averaged spectrum from T-7.4 to T+16.6 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.08 +- 0.39. The fluence in the 15-150 keV band is 2.6 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+5.57 sec in the 15-150 keV band is 0.2 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/345551/BA/ Given the weak nature of this event and the as yet unconfirmed nature of this trigger by the XRT follow-up observations, we can not rule out that this trigger is due something other than a GRB. There are further XRT follow-up observations in the observing plan.
GCN 8946 table
GRB_name GRB090307A
GCN_number 8946
Detection_method Swift-XRT Other
ra 244.9944°
decl -28.6333°
Circular_text TITLE: GCN CIRCULAR NUMBER: 8946 SUBJECT: GRB 090307: Swift-XRT afterglow confirmation and analysis DATE: 09/03/08 13:54:58 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT observed the field of GRB 090307 (BAT trigger 345551; GCN Circs. 8943, 8945) for 4.6 ks, from 135 s to 80 ks after the BAT trigger. All of the data were taken in Photon Counting (PC) mode. The X-ray source reported by Evans et al. (GCN Circ. 8943) is seen to fade, and is therefore identified as the afterglow, confirming the GRB nature of this BAT trigger. The source has an enhanced XRT position: RA, Dec = 244.9944, -28.6333 which is equivalent to: RA (J2000): 16 19 58.64 Dec (J2000): -28 37 59.9 with an uncertainty of 2.1 arcsec (radius, 90% confidence). The light curve shows a power-law decay, with an index 0.7 (+0.2, -0.1). The PC mode spectrum can be fitted with an absorbed power-law, with a photon index of 2.21 (+0.72, -0.60) and an absorbing column of 3.5 (+2.7,-1.1) e21 cm-2, in excess of the Galactic value of 1.3e21 cm-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10-11 (7.6 x 10-11) erg cm-2 count-1. If the light curve continues to decay with alpha=0.7, the XRT count-rate at T+48 hrs will be 0.002 counts s-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.38e-14 (1.4e-13) erg cm-2 s-1. The results of the automatic XRT analysis are available online at http://www.swift.ac.uk/xrt_products/00345551. This circular is an official product of the Swift-XRT team.
GCN 8959 table
GRB_name GRB090307A
GCN_number 8959
Detection_method GROND
Circular_text TITLE: GCN CIRCULAR NUMBER: 8959 SUBJECT: GRB 090307: GROND Upper Limits DATE: 09/03/09 13:45:36 GMT FROM: Christian Clemens at MPE 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 090307 (Swift trigger 345551; Barthelmy et al., GCN #8945) 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 05:06 UT on March 7, 80 min after the GRB trigger, and continued for 66 min. They were performed at an average seeing of 1.2" and at an average airmass of 1.8. We do not detect a source within the Swift-XRT error circle reported by Evans et al. (GCN #8946) down to (all in AB system) g' > 23.3, r' > 23.7, i' > 23.2, z' > 22.9, J > 21.7, H > 21.2 and K > 20.3. 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)= 0.528 in the direction of the burst (Schlegel et al. 1998).
GCN 8974 table
GRB_name GRB090307A
GCN_number 8974
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 8974 SUBJECT: GRB 090307A: TAROT Calern observatory optical observations DATE: 09/03/10 23:27:24 GMT FROM: Alain Klotz at CESR-CNRS Klotz, A. (CESR-OMP), Gendre, B. (LAM-OAMP), Boer M. (OHP-OAMP), Atteia J.L. (LATT-OMP) report: We imaged the field of GRB 090307A detected by SWIFT (trigger 345551) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. The observations started 373.3s after the GRB trigger The elevation of the field increased from 16 degrees above horizon and weather conditions were good. The first image has a duration of 90.0s. We do not detect any OT at the XRT position (Evans GCNC 8946) with a limiting magnitude of: t0+373.3s to t0+463.3s : R > 16.5 We co-added a series of exposures: t0+373.3s to t0+1062.0s : R > 18.9 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon=348.7859 lat=+15.1296 and the galactic extinction in R band is ~1.4 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S. This message may be cited.