A. D'Ai (INAF-IASFPA) and M.G. Bernardini (INAF-OAB) for the Swift team
At 16:14:21 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 230414B (trigger=1164180) (D'Ai et al. GCN Circ. 33612). Swift slewed immediately to the burst. At the time of the trigger, the initial BAT position was 115° from the Sun (10.6 hours East) and 134° from the 35%-illuminated Moon. 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.
Fernandez et al. (GCN Circ. 33629) determined a redshift of 3.568 from GTC. 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.
BAT refined results are not available.
Analysis of the initial XRT data was reported by Bernardini et al. (GCN Circ. 33626). We have analysed 20 ks of XRT data for GRB 230414B, from 112 s to 193.9 ks after the BAT trigger. The data comprise 17 s in Windowed Timing (WT) mode (the first 10 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 33613).
The late-time light curve (Figure 2) (from T0+4.4 ks) can be modelled with an initial rise, with a power-law index of α=-0.06 (+0.14, -0.27), followed by a break at T+38.3 ks to an α of 2.2 (+0.4, -0.5).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.03 (+0.15, -0.14). The best-fitting absorption column is 3.4 (+3.0, -1.7) x 1
A summary of the PC-mode spectrum is thus:
Total column: 3.4 (+3.0, -1.7) x 1
Galactic foreground: 1.7 x 1
Excess significance: <1.6 σ
Photon index: 2.03 (+0.15, -0.14)
The results of the XRT team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01164180.
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
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 |
|---|---|---|---|---|
| 1 |
+53°09'15.7" | 2.0" | XRT-final | UKSSDC |
| 1 |
+53°09'15.6" | 2.2" | XRT-enhanced | Goad et al. GCN Circ. 33621 |
| 1 |
+53°07'36" | 3' | BAT-initial | D'Ai et al. GCN Circ. 33612 |
| Band | Authors | GCN Circ. | Subject | Observatory | Notes |
|---|---|---|---|---|---|
| Optical | Lipunov et al. | 33614 | Swift GRB 230414B: Global MASTER-Net observations report |
MASTER | |
| Optical | Lu et al. | 33616 | Nanshan/HMT optical afterglow detection | Xinjiang Astro. Obs. | detection |
| Optical | Pankov et al. | 33617 | (correction GRB name in the GCN Circ. 33615): Mondy optical afterglow candidate |
Mondy | detection |
| Optical | Raman et al. | 33618 | GROWTH India Telescope afterglow confirmation |
GROWTH-India | detection |
| Optical | Ghosh et al. | 33620 | 1.3m DFOT Optical observations | DFOT | detection |
| Optical | Moskvitin and Goranskij | 33622 | SAO RAS optical observations | SAO RAS | detection |
| Optical | Malesani et al. | 33623 | slow optical light curve decay | NOT | light curve |
| Optical | Zhu et al. | 33625 | Dabancheng/GHOST optical observations | detection | |
| Optical | Belkin et al. | 33628 | AbAO optical observations | Abastumani Astro. Obs. | detection |
| Optical | Fernandez et al. | 33629 | Redshift from OSIRIS/GTC | GTC | redshift |
| Optical | Quadri | 33630 | Bassano Bresciano Observatory optical observations |
Bassano Bresciano Obs. | detection |
| Optical | Chen et al. | 33631 | Lulin 40cm-SLT optical limit | Lulin | upper limits |
| Optical | Leonini et al. | 33634 | Montarrenti Observatory late time optical afterglow detection |
Montarrenti | detection |
| Optical | Ror et al. | 33636 | 3.6m DOT Optical observations, slow decay at early epochs |
DOT | detection |
April 17, 2023