Swift Observations of GRB 200613A

J.A. Kennea (PSU) and F.E. Marshall (NASA/GSFC) for the Swift team

1. Introduction

Ohno et al. (GCN Circ. 27931) reported the GRB detection. On June 13, 2020, Fermi-LAT detected high-energy emission from GRB 200613A, which was also detected by Fermi-GBM at T0 = 05:30:08 UT (GCN Circ. 27926, Bissaldi et al. GCN Circ. 27930). Table 1 contains the best reported positions from Swift.

Pozanenko et al. (GCN Circ. 27937) reported the position from Abastumani Astro. Obs. for the optical afterglow of this GRB. Marshall (GCN Circ. 27944) reported the detection with UVOT of an optical afterglow. de Ugarte Postigo et al. (GCN Circ. 29320) determined a redshift of 1.2280 from GTC. Table 2 is a summary of GCN Circulars about this GRB from observatories other than Swift.

2. BAT Observations and Analysis

BAT did not observe this burst.

3. XRT Observations and Analysis

Analysis of the initial XRT data was reported by Kennea et al. (GCN Circ. 27936).

The light curve (Figure 2) can be modelled with a power-law decay with a decay index of α=1.6 ± 0.5.

A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.89 (+0.14, -0.13). The best-fitting absorption column is 2.3 ± 0.5 x 10²¹ cm^-2, in excess of the Galactic value of 8.4 x 10¹⁹ cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (4.7 x 10^-11) erg cm^-2 count^-1.

4. UVOT Observations and Analysis

Analysis of the UVOT data was reported by Marshall (GCN Circ. 27944). 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 E_B-V of 0.01 mag. in the direction of the GRB (Schlegel et al. 1998).

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

10^h12^m10.03^s +45°45'14.1" 0.46" UVOT-refined Marshall GCN Circ. 27944

10^h12^m10.08^s +45°45'14.7" 1.4" XRT Kennea et al. GCN Circ. 27936

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Optical Lipunov et al. 27933 Fermi GRB 200613A: Global MASTER-Net
observations report MASTER

Optical Kann et al. 27935 Candidate afterglow from OAJ Obs. Astro. de Javalambre detection

Optical Pozanenko et al. 27937 Kitab and AbAO optical afterglow
observations, host galaxy candidate Abastumani Astro. Obs.

Optical Kann 27938 OAJ Afterglow: Error in Coordinates Obs. Astro. de Javalambre

Optical Kitab and AbAO 27939 Liverpool Telescope observations Liverpool Telescope detection

Optical Zhu et al. 27943 Xinglong-2.16m optical observations Xinglong detection

Optical Liu et al. 27949 Continued Xinglong-2.16m optical
observations Xinglong

Optical Belkin et al. 27958 continued AbAO optical afterglow
observations Abastumani Astro. Obs. detection

Optical Murata et al. 27962 MITSuME Akeno optical upper limits MITSuME Akeno upper limits

Optical Fu et al. 27971 Jet-break from Xinglong-2.16m optical
observations Xinglong

Optical Belkin et al. 27978 Mondy optical observations Mondy detection

Optical Moskvitin 27982 SAO RAS optical observations SAO RAS

Optical Belkin et al. 27983 continued Kitab optical observations detection

Optical Izzo 27998 Further Liverpool Telescope observations Liverpool Telescope

Optical Dutta et al. 27999 R-band observations from HCT Himalayan Chandra Telescope

Optical Belkin et al. 28000 CrAO optical observations CrAO detection

Optical Belkin et al. 28003 Continued CrAO optical observations CrAO detection

Optical de Ugarte Postigo et al. 29320 Host galaxy redshift from OSIRIS/GTC GTC redshift

Gamma-ray Fermi 27926 Fermi GBM Final Real-time Localization Fermi GBM

Gamma-ray Kunzweiler et al. 27927 BALROG localization (Fermi Trigger
613719013 / GRB 200613229) BALROG

Gamma-ray Bissaldi and Lesage 27930 Fermi GBM observation Fermi GBM E_peak=111±3 keV
T₉₀=470 seconds
Fluence=4.10±0.05x10^-5erg cm^-2
(93^rd percentile for long GRBs)

Gamma-ray Ohno et al. 27931 Fermi-LAT detection Fermi LAT E_max=7.6 GeV

Gamma-ray Yamaoka et al. 27964 CALET Gamma-Ray Burst Monitor detection CALET

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

Filter T_start(s) T_stop(s) Exp(s) Mag

white 44416 45204 775 19.65 ± 0.07

v 45211 45427 213 >18.6

u 43621 44409 775 19.02 ± 0.12

RA (J2000)	Dec (J2000)	Error	Note	Reference
10^h12^m10.03^s	+45°45'14.1"	0.46"	UVOT-refined	Marshall GCN Circ. 27944
10^h12^m10.08^s	+45°45'14.7"	1.4"	XRT	Kennea et al. GCN Circ. 27936

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Optical	Lipunov et al.	27933	Fermi GRB 200613A: Global MASTER-Net observations report	MASTER
Optical	Kann et al.	27935	Candidate afterglow from OAJ	Obs. Astro. de Javalambre	detection
Optical	Pozanenko et al.	27937	Kitab and AbAO optical afterglow observations, host galaxy candidate	Abastumani Astro. Obs.
Optical	Kann	27938	OAJ Afterglow: Error in Coordinates	Obs. Astro. de Javalambre
Optical	Kitab and AbAO	27939	Liverpool Telescope observations	Liverpool Telescope	detection
Optical	Zhu et al.	27943	Xinglong-2.16m optical observations	Xinglong	detection
Optical	Liu et al.	27949	Continued Xinglong-2.16m optical observations	Xinglong
Optical	Belkin et al.	27958	continued AbAO optical afterglow observations	Abastumani Astro. Obs.	detection
Optical	Murata et al.	27962	MITSuME Akeno optical upper limits	MITSuME Akeno	upper limits
Optical	Fu et al.	27971	Jet-break from Xinglong-2.16m optical observations	Xinglong
Optical	Belkin et al.	27978	Mondy optical observations	Mondy	detection
Optical	Moskvitin	27982	SAO RAS optical observations	SAO RAS
Optical	Belkin et al.	27983	continued Kitab optical observations		detection
Optical	Izzo	27998	Further Liverpool Telescope observations	Liverpool Telescope
Optical	Dutta et al.	27999	R-band observations from HCT	Himalayan Chandra Telescope
Optical	Belkin et al.	28000	CrAO optical observations	CrAO	detection
Optical	Belkin et al.	28003	Continued CrAO optical observations	CrAO	detection
Optical	de Ugarte Postigo et al.	29320	Host galaxy redshift from OSIRIS/GTC	GTC	redshift
Gamma-ray	Fermi	27926	Fermi GBM Final Real-time Localization	Fermi GBM
Gamma-ray	Kunzweiler et al.	27927	BALROG localization (Fermi Trigger 613719013 / GRB 200613229)	BALROG
Gamma-ray	Bissaldi and Lesage	27930	Fermi GBM observation	Fermi GBM	E_peak=111±3 keV T₉₀=470 seconds Fluence=4.10±0.05x10^-5erg cm^-2 (93^rd percentile for long GRBs)
Gamma-ray	Ohno et al.	27931	Fermi-LAT detection	Fermi LAT	E_max=7.6 GeV
Gamma-ray	Yamaoka et al.	27964	CALET Gamma-Ray Burst Monitor detection	CALET

Filter	T_start(s)	T_stop(s)	Exp(s)	Mag
white	44416	45204	775	19.65 ± 0.07
v	45211	45427	213	>18.6
u	43621	44409	775	19.02 ± 0.12

Table 3. UVOT observations reported by Marshall (GCN Circ. 27944). 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.

January 19, 2021