Swift Observations of GRB 220708B

J.P. Osborne (U. Leicester) for the Swift team

1. Introduction

Tohuvavohu et al. (GCN Circ. 32345) reported the GRB detection. Swift/BAT did not localize GRB 220708B onboard (T0: 2022-07-08T02:06:67 UTC, CALET trig #1341281218). 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.

2. BAT Observations and Analysis

BAT refined results are not available.

3. XRT Observations and Analysis

Analysis of the initial XRT data was reported by Osborne et al. (GCN Circ. 32350). The light curve is consistent with a constant source of mean count rate 6.5 x 10^-2 ct s^-1.

A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.3 (+0.6, -0.5). The best-fitting absorption column is 3.2 (+2.2, -1.7) x 10²¹ cm^-2, in excess of the Galactic value of 1.4 x 10²⁰ cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.2 x 10^-11 (5.7 x 10^-11) erg cm^-2 count^-1.

4. UVOT Observations and Analysis

UVOT results are not available.

Figure 1. The BAT light curve is not available.

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

16^h34^m19.32^s +36°20'55.0" 2.2" XRT-final UKSSDC

16^h34^m18.97^s +36°20'52.0" 4.0" XRT Osborne et al. GCN Circ. 32350

16^h34^m36.48^s +36°20'16.8" 5' BAT-GUANO Tohuvavohu et al. GCN Circ. 32345

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Optical Jiang et al. 32355 Nanshan/NEXT optical upper limits Xinjiang Astro. Obs. upper limits

Optical Turpin et al. 32360 T193-OHP optical upper limit upper limits

Optical Swain et al. 32363 GIT optical upper limits GROWTH-India Tel. upper limits

Gamma-ray Kobayashi et al. 32356 CALET Gamma-Ray Burst Monitor detection CALET

Gamma-ray Frederiks et al. 32358 Konus-Wind detection Konus-Wind E_peak=90 (-9,+11) keV

Gamma-ray Frederiks 32359 Konus-Wind detection of GRB 220708B
(Correction to GCN Circ. 32358) Konus-Wind

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

RA (J2000)	Dec (J2000)	Error	Note	Reference
16^h34^m19.32^s	+36°20'55.0"	2.2"	XRT-final	UKSSDC
16^h34^m18.97^s	+36°20'52.0"	4.0"	XRT	Osborne et al. GCN Circ. 32350
16^h34^m36.48^s	+36°20'16.8"	5'	BAT-GUANO	Tohuvavohu et al. GCN Circ. 32345

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Optical	Jiang et al.	32355	Nanshan/NEXT optical upper limits	Xinjiang Astro. Obs.	upper limits
Optical	Turpin et al.	32360	T193-OHP optical upper limit		upper limits
Optical	Swain et al.	32363	GIT optical upper limits	GROWTH-India Tel.	upper limits
Gamma-ray	Kobayashi et al.	32356	CALET Gamma-Ray Burst Monitor detection	CALET
Gamma-ray	Frederiks et al.	32358	Konus-Wind detection	Konus-Wind	E_peak=90 (-9,+11) keV
Gamma-ray	Frederiks	32359	Konus-Wind detection of GRB 220708B (Correction to GCN Circ. 32358)	Konus-Wind

July 12, 2022