HETE Burst H3557

Burst H3557 summary

  • Trigger time is
    • UTC=20040912_141216
    • GRB=GRB040912+51136
  • Triggering instrument was Fregate
  • Trigger timescale was 5.2 seconds
  • Trigger detected in 5-120 keV band


Evaluation GRB040912



XRF, localized by WXM, ground analysis sent out.



Download ASCII table of Fregate Band A, B, C lightcurves here.

The color of trigger H3557, defined by the ratio of total counts in Fregate band C (30-400 keV) to band A (7-40 keV) vs. band B (7-80 keV) to band A, overlaid on a the color-color plot of all localized bursts detected to date. Note the separation of XRFs, XRRs, and GRBs.

The signal to noise in Fregate band C (30-400 keV) of trigger H3557 in relation to the S/N of band C of other localized HETE triggers. We find empirically that most XRFs are faint and soft: the fact that localized bursts require a minimum S/N in the 2-25 keV band means that the band C S/N should be low. We find a cutoff in the band C S/N of 6.5 delineates the XRF/non-XRF population with high reliability.

An automated fit of a cutoff power-law spectrum has been performed for H3557. The fit of the model to the data is shown below; the calculated values of Epeak and the burst fluence (25-100 keV) are: 

	Epeak    = 53.55 keV
	Fluence  = 1.881e-06 erg/cm^2
	Duration = 27.000 seconds
	PseudoZ  = 2.163

CAUTION:

These results are computed by an automatic script. Please visually inspect the XSPEC summary plot to judge the quality of the results.

Please note that this value of Epeak results from a fit to FREGATE data (8-400 keV) only -- a more reliable joint fit to FREGATE and WXM data is not yet automated. As such, this Epeak estimate is likely to be biased high, especially for soft events, such as XRFs. In our experience, the inclusion of WXM data can lower the value of E_peak substantially. The above Epeak value should thus be viewed as a preliminary estimate. As better fits become available, the information will be posted here.

Click here for an explanation of the method.

Link to Jochen Greiner's web page on

Skymap for HETE trigger H3557

20 ksec Chandra Exposure of the WXM Error Region (GCN) 

 #      Chandra Name           RA           DEC         Cts   HR
 1 CXOU J235631.0-005946    23 56 30.96  -0  59 46.1    55   -0.5
 2 CXOU J235700.0-010009    23 56 59.96  -1   0  9.7    40   -0.3
 3 CXOU J235712.2-005942    23 57 12.17  -0  59 42.1    33   -0.3
 4 CXOU J235642.9-005520    23 56 42.91  -0  55 20.4    32   -0.7
 5 CXOU J235645.7-005655    23 56 46.71  -0  56 54.9    32   -0.3
 6 CXOU J235707.6-005713    23 57  7.57  -0  57 12.6    31    0.8
 7 CXOU J235716.4-010109    23 57 16.37  -1   1  8.7    27   -0.2
 8 CXOU J235639.1-005556    23 56 39.10  -0  55 55.8    20    0.9
 9 CXOU J235651.2-005513    23 56 51.17  -0  55 12.5    17   -0.3
10 CXOU J235636.7-005431    23 56 36.74  -0  54 31.2    15   -0.6
11 CXOU J235711.1-005637    23 57 11.12  -0  56 37.1    12   -0.2
12 CXOU J235637.3-010160    23 56 37.26  -1   1 59.9    12   -0.6
13 CXOU J235656.4-005839    23 56 56.42  -0  58 39.2    11   -0.1
14 CXOU J235700.1-005713    23 57  0.09  -0  57 12.6    11   -1.0
15 CXOU J235659.8-005903    23 56 59.83  -0  59  2.8    10   -0.6
16 CXOU J235649.1-010344    23 56 49.07  -1   3 44.2     9    0.4
17 CXOU J235700.4-010018    23 57  0.36  -1   0 17.6     9   -0.7
18 CXOU J235646.4_005621    23 56 46.45  -0  56 21.4     8    1.1
19 CXOU J235647.0-010045    23 56 46.97  -1   0 45.1     8    0.0
20 CXOU J235648.8-010319    23 56 48.81  -1   3 18.6     8   -1.0
21 CXOU J235704.0-005859    23 57  4.03  -0  58 58.8     8   -0.2
22 CXOU J235707.2-010420    23 57  7.18  -1   4 19.6     7    0.4

Link to Jochen Greiner's web page on GRB040912