Swift Observations of GRB 160101A

L. Izzo (URoma/ICRA) and M.H. Siegel (PSU) for the Swift team

1. Introduction

Itoh et al. (GCN Circ. 18793) reported the GRB detection. The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 00:43:52 UT on 2016 January 1. Table 1 contains the best reported positions from Swift.

Siegel and D'Elia (GCN Circ. 18797) 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 tiled observations (Siegel and D'Elia GCN Circ. 18797) of the field of the MAXI-detected burst GRB 160101A (Itoh et al. GCN Circ. 18793) 13.2 ks after the burst. A fading optical source consistent with position of the XRT source reported by Izzo et al. (GCN Circ. 18795) is detected in the initial UVOT exposures in the u filter. 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 0.09 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

14^h38^m36.12^s -13°48'55.4" 0.58" UVOT-refined Siegel and D'Elia GCN Circ. 18797

14^h38^m36.14^s -13°48'55.5" 3.7" XRT Izzo et al. GCN Circ. 18795

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Optical Fujiwara et al. 18805 MITSuME Akeno optical upper limits MITSuME Akeno upper limits

X-ray Itoh et al. 18793 MAXI/GSC detection MAXI detection

Gamma-ray Veres 18796 Fermi GBM observation Fermi GBM E_peak=135.0±5.2 keV
T₉₀=4.7 seconds
Fluence=1.682±0.024x10^-6erg cm^-2
(26^th percentile for long GRBs)

Gamma-ray Golenetskii et al. 18838 Konus-Wind observation Konus-Wind E_peak=612 (-175,+321) keV
Fluence=1.47(-0.17,+0.21)x10^-5erg cm^-2

Other Yamada et al. 18814 CALET Gamma-Ray Burst Monitor detection detection

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

u 13195 13397 198 17.55± 0.10

u 19592 19652 59 18.32± 0.32

RA (J2000)	Dec (J2000)	Error	Note	Reference
14^h38^m36.12^s	-13°48'55.4"	0.58"	UVOT-refined	Siegel and D'Elia GCN Circ. 18797
14^h38^m36.14^s	-13°48'55.5"	3.7"	XRT	Izzo et al. GCN Circ. 18795

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Optical	Fujiwara et al.	18805	MITSuME Akeno optical upper limits	MITSuME Akeno	upper limits
X-ray	Itoh et al.	18793	MAXI/GSC detection	MAXI	detection
Gamma-ray	Veres	18796	Fermi GBM observation	Fermi GBM	E_peak=135.0±5.2 keV T₉₀=4.7 seconds Fluence=1.682±0.024x10^-6erg cm^-2 (26^th percentile for long GRBs)
Gamma-ray	Golenetskii et al.	18838	Konus-Wind observation	Konus-Wind	E_peak=612 (-175,+321) keV Fluence=1.47(-0.17,+0.21)x10^-5erg cm^-2
Other	Yamada et al.	18814	CALET Gamma-Ray Burst Monitor detection		detection

Filter	T_start(s)	T_stop(s)	Exp(s)	Mag
u	13195	13397	198	17.55± 0.10
u	19592	19652	59	18.32± 0.32

Table 3. UVOT observations reported by Siegel and D'Elia (GCN Circ. 18797). 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 13, 2016