K.L. Page (U. Leicester) and A. D'Ai (INAF-IASFPA) for the Swift team
At 14:42:24 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 190816A (trigger=920783) (Page et al. GCN Circ. 25368). Swift did not slew due to an observing constraint. At the time of the trigger, the initial BAT position was 158° from the Sun (11.0 hours West) and 17° from the 99%-illuminated Moon. Table 1 contains the best reported positions from Swift.
Table 2 is a summary of GCN Circulars about this GRB from observatories other than Swift.
Standard analysis products for this burst are available at https://gcn.gsfc.nasa.gov/swift_gnd_ana.html.
As reported by Ukwatta et al. (GCN Circ. 25405),
the BAT ground-calculated position is RA, Dec = 341.183, -29.745 deg which is RA(J2000) = 2
The mask-weighted light curve (Figure 1) shows a weak multi-pulse structure that starts at ~ T-200 s and ends at ~T+340 s.
The time-averaged spectrum from T-206.5 to T+341.6 s is best fit by a simple power-law model.
The power law index of the time-averaged spectrum is 1.62 ± 0.11.
The fluence in the 15-150 keV band is 9.8 ± 0.6 x 1
The results of the batgrbproduct analysis are available at https://gcn.gsfc.nasa.gov/notices_s/920783/BA/.
Analysis of the initial XRT data was reported by D'Ai et al. (GCN Circ. 25473). The source previously reported by D'Ai et al. (GCN Circ. 25399), "Source 4", is fading with 3-sigma significance, and is therefore likely the GRB afterglow. The source is fading with α >0.5.
UVOT results are not available.
Figure 1. The BAT
mask-weighted light curve in the four individual and total
energy bands. The units are counts
RA (J2000) | Dec (J2000) | Error | Note | Reference |
---|---|---|---|---|
2 |
-29°45'27.4" | 4.9" | XRT | D'Ai et al. GCN Circ. 25473 |
2 |
-29°44'42.5" | 1.7' | BAT-refined | Ukwatta et al. GCN Circ. 25405 |
Band | Authors | GCN Circ. | Subject | Observatory | Notes |
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August 26, 2019