V. D'Elia (SSDC and INAF-OAR) and S.R. Oates (UCL-MSSL) for the Swift team
Mereghetti et al. (GCN Circ. 16004) reported the GRB detection. A gamma ray burst lasting about 100 s has been detected by IBAS in the IBIS/ISGRI data at 09:26:00 UT of March 20. Table 1 contains the best reported positions from Swift, and the latest XRT position can be viewed at http://www.swift.ac.uk/xrt_positions.
Guidorzi et al. (GCN Circ. 16003) reported the position from FTN for the optical afterglow of this GRB. Table 2 is a summary of GCN Circulars about this GRB from observatories other than Swift.
BAT did not observe this burst.
Analysis of the initial XRT data was reported by D'Elia et al. (GCN Circ. 29371).
We have analysed 6.0 ks of XRT data for the INTEGRAL-detected burst GRB 140320B (Pagani et al. GCN Circ. 16013), from 12.0 ks to 29.4 ks after the INTEGRAL trigger. The data are entirely in Photon Counting (PC) mode. We cannot determine at the present time whether the source is fading.
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.4 (+0.4, -0.3). The best-fitting absorption column is 7.2 (+7.1, -4.8) x 1
A summary of the PC-mode spectrum is thus:
Total column: 7.2 (+7.1, -4.8) x 1
Galactic foreground: 2.4 x 1
Excess significance: <1.6 σ
Photon index: 2.4 (+0.4, -0.3)
The results of the XRT team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020370.
The Swift/UVOT began settled observations
(Oates and Starling GCN Circ. 16019) of the field of GRB 140320B 11975 s after the INTEGRAL trigger (Mereghetti et al., GCN Circ. 16004).
No optical afterglow consistent with the XRT position (Pagani et al., GCN Circ. 16013) and the FTN optical position (Guidorzi et al., GCN Circ. 16003) is detected in the initial UVOT exposures.
Table 3 gives preliminary
magnitudes using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc., 1358, 373).
No correction has been made for the expected extinction in the Milky Way
corresponding to a reddening of
Figure 1. The BAT light curve is not available.
Figure 2. The XRT light curve.
Any data from a crosshatched region are not included in the fit.
RA (J2000) | Dec (J2000) | Error | Note | Reference |
---|---|---|---|---|
0 |
+60°16'08.3" | 3.6" | XRT-final | UKSSDC |
0 |
+60°16'08.3" | 3.6" | XRT-refined | D'Elia et al. GCN Circ. 29371 |
Band | Authors | GCN Circ. | Subject | Observatory | Notes |
---|---|---|---|---|---|
Optical | Guidorzi et al. | 16003 | FTN optical afterglow candidate | FTN | detection |
Optical | Elenin et al. | 16005 | ISON-NM optical observations | ISON-NM | detection |
Optical | Xin et al. | 16006 | Xinglong TNT upper limit | TNT | upper limits |
Optical | Perley and Cenko | 16024 | P60 detection of a very red afterglow | Palomar 60-inch | detection |
Gamma-ray | Mereghetti et al. | 16004 | A long GRB detected by INTEGRAL | INTEGRAL | Fluence=5x1 |
Filter | Exp(s) | Mag | ||
---|---|---|---|---|
white | 11975 | 29408 | 5864 | >23.1 |
Table 3. UVOT observation reported by Oates and Starling (GCN Circ. 16019). The start and stop time of the exposure are given in seconds since the BAT trigger. The preliminary 3-σ upper limit is given. No correction has been made for extinction in the Milky Way.
January 30, 2021