Swift Observations of GRB 201010A

K.L. Page (U. Leicester) and J.P. Osborne (U. Leicester) for the Swift team

1. Introduction

At 14:49:24 UT, the Swift Burst Alert Telescope (BAT) triggered and located SGR 1830-0645 or GRB 201010A (trigger=999571) (Page et al. GCN Circ. 28594). Swift slewed immediately to the burst. At the time of the trigger, the initial BAT position was 81° from the Sun (5.4 hours East) and 155° from the 44%-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.

2. BAT Observations and Analysis

BAT refined results are not available.

3. XRT Observations and Analysis

We have analysed 6.2 ks of XRT data for GRB 201010A, from 82 s to 28.4 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 28596). The late-time light curve (from T0+5.0 ks) is consistent with a constant source of mean count rate 8.9 x 10^-1 ct s^-1. A power-law fit gives an index of 0.01 (+0.09, -0.10).

A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.99 (+0.19, -0.18). The best-fitting absorption column is 2.14 (+0.31, -0.28) x 10²² cm^-2, in excess of the Galactic value of 1.1 x 10²² cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 6.2 x 10^-11 (1.4 x 10^-10) erg cm^-2 count^-1.

A summary of the PC-mode spectrum is thus:
Total column: 2.14 (+0.31, -0.28) x 10²² cm^-2
Galactic foreground: 1.1 x 10²² cm^-2
Excess significance: 6.0 σ
Photon index: 1.99 (+0.19, -0.18)

The results of the XRT team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00999571.

4. UVOT Observations and Analysis

UVOT results are not available.

BAT light curve

Figure 1. The BAT mask-weighted light curve in the four individual and total energy bands. The units are counts s^-1 illuminated-detector^-1. The vertical green dash-dotted lines show the T₅₀ interval, the vertical black dashed lines show the T₉₀ interval, and vertical blue (orange) solid lines show the start (stop) of slews.

XRT light curve

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

18^h30^m41.72^s -06°45'16.4" 1.4" XRT-enhanced Osborne et al. GCN Circ. 28596

18^h30^m42^s -06°45'30" 3' BAT-initial Page et al. GCN Circ. 28594

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Optical Lipunov et al. 28595 Swift GRB201010.62: Global MASTER-Net
observations report MASTER

Optical Belkin et al. 28597 SGR 1830-0645 / GRB 201010A: Kitab
optical non-detection

Optical Hu et al. 28601 SGR 1830-0645 / GRB 201010A: 1.5m OSN
optical upper limit Obs.de Sierra Nevada upper limits

Table 2. Summary of GCN Circulars from other observatories sorted by band and then circular number.

RA (J2000)	Dec (J2000)	Error	Note	Reference
18^h30^m41.72^s	-06°45'16.4"	1.4"	XRT-enhanced	Osborne et al. GCN Circ. 28596
18^h30^m42^s	-06°45'30"	3'	BAT-initial	Page et al. GCN Circ. 28594

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Optical	Lipunov et al.	28595	Swift GRB201010.62: Global MASTER-Net observations report	MASTER
Optical	Belkin et al.	28597	SGR 1830-0645 / GRB 201010A: Kitab optical non-detection
Optical	Hu et al.	28601	SGR 1830-0645 / GRB 201010A: 1.5m OSN optical upper limit	Obs.de Sierra Nevada	upper limits

October 12, 2020