J.D. Gropp (PSU) and M. Perri (SSDC and INAF-OAR) for the Swift team
At 17:58:26 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 201223A (trigger=1014316) (Gropp et al. GCN Circ. 29158). Swift slewed immediately to the burst. At the time of the trigger, the initial BAT position was 127° from the Sun (9.3 hours West) and 93° from the 67%-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.
Gropp et al. (GCN Circ. 29158) reported the detection with UVOT of an optical afterglow. 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 Laha et al. (GCN Circ. 29163),
the BAT ground-calculated position is RA, Dec = 132.735, 71.176 deg which is RA(J2000) = 0
The mask-weighted light curve (Figure 1) shows a multi-peaked structure that starts at ~T-25 s and ends at ~T+8 s.
The main peak occurs at ~
The time-averaged spectrum from T-25.18 to T+7.82 s is best fit by a simple power-law model.
The power law index of the time-averaged spectrum is 1.35 ± 0.13.
The fluence in the 15-150 keV band is 1.3 ± 0.1 x 1
The results of the batgrbproduct analysis are available at https://gcn.gsfc.nasa.gov/notices_s/1014316/BA/.
Analysis of the initial XRT data was reported by Perri et al. (GCN Circ. 29171). We have analysed 19 ks of XRT data for GRB 201223A, from 81 s to 504.6 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 29170).
The light curve (Figure 2) can be modelled with an initial power-law decay with an index of α=0.42 ± 0.16, followed by a break at T+2679 s to an α of 1.54 (+0.18, -0.17).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.87 (+0.18, -0.13). The best-fitting absorption column is 4.1 (+4.0, -0.9) x 1
A summary of the PC-mode spectrum is thus:
Total column: 4.1 (+4.0, -0.9) x 1
Galactic foreground: 3.1 x 1
Excess significance: <1.6 σ
Photon index: 1.87 (+0.18, -0.13)
The results of the XRT team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01014316.
Analysis of the UVOT data was reported by Gropp (GCN Circ. 29177).
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
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 |
---|---|---|---|---|
0 |
+71°10'47.4" | 0.42" | UVOT-refined | Gropp GCN Circ. 29177 |
0 |
+71°10'45.3" | 1.5" | XRT-final | UKSSDC |
0 |
+71°10'45.2" | 1.8" | XRT-enhanced | Goad et al. GCN Circ. 29170 |
0 |
+71°10'34.9" | 1.4' | BAT-refined | Laha et al. GCN Circ. 29163 |
Band | Authors | GCN Circ. | Subject | Observatory | Notes |
---|---|---|---|---|---|
Optical | Lipunov et al. | 29156 | Swift GRB201223.75: Global MASTER-Net observations report |
MASTER | |
Optical | Lipunov et al. | 29157 | Swift GRB201223.75: Global MASTER-Net OT detection |
MASTER | detection |
Optical | Zhu et al. | 29159 | Nanshan/NEXT early optical afterglow detection |
Xinjiang Astro. Obs. | detection |
Optical | Hu et al. | 29160 | BOOTES-4/MET early optical observation | BOOTES-4 | detection |
Optical | Hosokawa et al. | 29164 | MITSuME Akeno optical observation | MITSuME Akeno | detection |
Optical | 29165 | iTelescope optical afterglow observations |
iTelescope | ||
Optical | Xin et al. | 29166 | GWAC-F60A optical afterglow observations | Xinglong Obs. | |
Optical | Belkin et al. | 29167 | Mondy and Kitab optical observations | Mondy | detection |
Optical | Kumar et al. | 29168 | GROWTH-India Telescope (GIT) photometric follow-up. |
GROWTH-India | detection |
Optical | Xu et al. | 29169 | NOT optical upper limit and NEXT powerlaw decay |
NOT | upper limits |
Optical | Gupta et al. | 29173 | 1.3m DFOT and 1.04m ST optical observations |
Devasthal Opt.Tel. | detection |
Optical | Pankov et al. | 29174 | AbAO optical observations | Abastumani Astro. Obs. | detection |
Optical | Kumar et al. | 29176 | HCT optical upper limit | Himalayan Chandra Telescope | upper limits |
Optical | Nakamura et al. | 29180 | AROMA-N Optical Observation | AROMA-N | |
Optical | Xin et al. | 29201 | SVOM-GWAC detected the optical counterpart during prompt emission phase |
Xinglong Obs. | detection |
Gamma-ray | Wood | 29161 | Fermi GBM Detection | Fermi GBM | Fluence=2.1±0.3x1 (3 |
Filter | Exp(s) | Mag | ||
---|---|---|---|---|
whit |
79 | 229 | 147 | 16.06±0.03 |
white | 571 | 1019 | 186 | 18.04±0.08 |
white | 5921 | 6121 | 196 | >20.17 |
white | 12121 | 12630 | 497 | 20.09±0.30 |
v | 621 | 1069 | 58 | >17.44 |
b | 547 | 1167 | 58 | 17.97±0.25 |
b | 11208 | 12115 | 885 | >20.38 |
292 | 541 | 246 | 16.75 ± 0.04 | |
u | 694 | 1142 | 38 | >17.58 |
w1 | 670 | 1118 | 58 | >17.65 |
m2 | 645 | 1093 | 58 | >17.87 |
w2 | 596 | 1045 | 58 | >17.81 |
Table 3. UVOT observations reported by Gropp (GCN Circ. 29177). The start and stop times of the exposures are given in seconds since the BAT trigger. The preliminary detections and 3-σ upper limits are given. No correction has been made for extinction in the Milky Way.
December 30, 2020