Swift Observations of GRB 150627A

B.P. Gompertz (U. Leicester) and P. Kuin (MSSL-UCL) for the Swift team

1. Introduction

Arimoto et al. (GCN Circ. 17971) reported the GRB detection. At 04:23:23.68 UT on June 27, 2015, Fermi-LAT detected high-energy emission from GRB 150627A, which was also detected by Fermi-GBM (trigger 457071806/ 150627183). Table 1 contains the best reported positions from Swift.

Kuin et al. (GCN Circ. 17977) 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.

2. BAT Observations and Analysis

BAT did not observe this burst.

3. XRT Observations and Analysis

XRT results are not available.

4. UVOT Observations and Analysis

The Swift/UVOT began settled observations (Kuin et al. GCN Circ. 17977) of the field of the Fermi GRB 150627A 33622 s after the LAT trigger (Arimoto et al., GCN Circ. 17971; Yu et al., GCN Circ. 17975). 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 0.32 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

07^h49^m53.06^s -51°29'21.9" 0.99" UVOT GCN Circ. 17977

07^h49^m52.97^s -51°29'22.4" 1.4" XRT-final UKSSDC

07^h49^m52.94^s -51°29'23.9" 3.5" XRT Gompertz et al. GCN Circ. 17976

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Optical Lipunov et al. 17978 MASTER-SAAO OT Detection Abastumani Astro. Obs. detection

Gamma-ray Arimoto et al. 17971 Fermi-LAT detection Fermi LAT E_max=8.1 GeV

Gamma-ray Yu et al. 17975 Fermi GBM observation Fermi GBM E_peak=233±5 keV
T₉₀=65 seconds
Fluence=1.90±0.01x10^-4erg cm^-2
(99.2 percentile for long GRBs)

Gamma-ray Golenetskii et al. 17982 Konus-Wind observation Konus-Wind Fluence=2.34(-0.11,+0.12)x10^-4erg cm^-2

Other Lipunov 17979 corection to 17978

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 33963 34289 335 19.11±0.10

white 39860 40112 248 19.55±0.17

white 45659 45863 204 19.28±0.14

v 34304 34601 298 19.02±0.32

v 40117 40346 225 18.98±0.36

u 33622 38243 577 18.90±0.10

u 43668 45654 966 19.00±0.11

RA (J2000)	Dec (J2000)	Error	Note	Reference
07^h49^m53.06^s	-51°29'21.9"	0.99"	UVOT	GCN Circ. 17977
07^h49^m52.97^s	-51°29'22.4"	1.4"	XRT-final	UKSSDC
07^h49^m52.94^s	-51°29'23.9"	3.5"	XRT	Gompertz et al. GCN Circ. 17976

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Optical	Lipunov et al.	17978	MASTER-SAAO OT Detection	Abastumani Astro. Obs.	detection
Gamma-ray	Arimoto et al.	17971	Fermi-LAT detection	Fermi LAT	E_max=8.1 GeV
Gamma-ray	Yu et al.	17975	Fermi GBM observation	Fermi GBM	E_peak=233±5 keV T₉₀=65 seconds Fluence=1.90±0.01x10^-4erg cm^-2 (99.2 percentile for long GRBs)
Gamma-ray	Golenetskii et al.	17982	Konus-Wind observation	Konus-Wind	Fluence=2.34(-0.11,+0.12)x10^-4erg cm^-2
Other	Lipunov	17979	corection to 17978

Filter	T_start(s)	T_stop(s)	Exp(s)	Mag
white	33963	34289	335	19.11±0.10
white	39860	40112	248	19.55±0.17
white	45659	45863	204	19.28±0.14
v	34304	34601	298	19.02±0.32
v	40117	40346	225	18.98±0.36
u	33622	38243	577	18.90±0.10
u	43668	45654	966	19.00±0.11

Table 3. UVOT observations reported by Kuin et al. (GCN Circ. 17977). 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.

June 30, 2015