Swift Observations of GRB 180806A

S.L. Gibson (U. Leicester) for the Swift team

1. Introduction

Malacaria et al. (GCN Circ. 23095) reported the GRB detection. At 22:38:59.66 UT on 06 August 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180806A (trigger 555287944 / 180806944). Table 1 contains the best reported positions from Swift.

Lipunov et al. (GCN Circ. 23091) reported the position from MASTER for the optical afterglow of this GRB. 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 Gibson et al. (GCN Circ. 23097). Two uncatalogued X-ray sources are detected, of which one ("Source 1") is fading with 3-sigma significance, and is therefore likely the GRB afterglow. The source is fading with α >2.2.

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

00^h46^m12.76^s +24°20'12.7" 4.2" XRT-final UKSSDC

00^h46^m12.86^s +24°20'13.2" 5.0" XRT Gibson et al. GCN Circ. 23097

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Optical Lipunov et al. 23091 94: MASTER possible OT detection in
Fermi GMB trigger 555287944 error box MASTER possible detection

Optical Watson et al. 23092 94: COATLI Detection of MASTER OT
J004613.05+242014.1 and Confirmation of
Fading COATLI detection

Optical Butler et al. 23094 180806.94: Refined COATLI Photometry of
MASTER OT J004613.05+242014.1 COATLI detection

Optical Watson et al. 23096 180806.98: RATIR Optical Observations
of MASTER OT J004613.05+242014.1 MASTER detection

Optical Malesani and Sagues 23098 NOT optical observations NOT detection

Gamma-ray Malacaria et al. 23095 Fermi GBM detection Fermi GBM E_peak=482.40±31.2 keV
Fluence=2.197±0.039x10^-5erg cm^-2

Gamma-ray Tsvetkova et al. 23119 Konus-Wind observation Konus-Wind E_peak=352 (-53,+59) keV
Duration=~20 seconds
Fluence=2.92(-0.36,+0.41)x10^-5erg cm^-2

Gamma-ray Sharma et al. 23122 AstroSat CZTI detection CZTI T₉₀=25.8 seconds

Other D'Ai 23101 correction to Circular 23097

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

RA (J2000)	Dec (J2000)	Error	Note	Reference
00^h46^m12.76^s	+24°20'12.7"	4.2"	XRT-final	UKSSDC
00^h46^m12.86^s	+24°20'13.2"	5.0"	XRT	Gibson et al. GCN Circ. 23097

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Optical	Lipunov et al.	23091	94: MASTER possible OT detection in Fermi GMB trigger 555287944 error box	MASTER	possible detection
Optical	Watson et al.	23092	94: COATLI Detection of MASTER OT J004613.05+242014.1 and Confirmation of Fading	COATLI	detection
Optical	Butler et al.	23094	180806.94: Refined COATLI Photometry of MASTER OT J004613.05+242014.1	COATLI	detection
Optical	Watson et al.	23096	180806.98: RATIR Optical Observations of MASTER OT J004613.05+242014.1	MASTER	detection
Optical	Malesani and Sagues	23098	NOT optical observations	NOT	detection
Gamma-ray	Malacaria et al.	23095	Fermi GBM detection	Fermi GBM	E_peak=482.40±31.2 keV Fluence=2.197±0.039x10^-5erg cm^-2
Gamma-ray	Tsvetkova et al.	23119	Konus-Wind observation	Konus-Wind	E_peak=352 (-53,+59) keV Duration=~20 seconds Fluence=2.92(-0.36,+0.41)x10^-5erg cm^-2
Gamma-ray	Sharma et al.	23122	AstroSat CZTI detection	CZTI	T₉₀=25.8 seconds
Other	D'Ai	23101	correction to Circular 23097

August 20, 2018