Swift Observations of GRB 151212A

T.G.R. Roegiers (PSU) and M. De Pasquale (PSU) for the Swift team

1. Introduction

Nakahira et al. (GCN Circ. 18685) reported the GRB detection. The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at UT 2015-12-12T14:00:27. Table 1 contains the best reported positions from Swift.

Wiseman et al. (GCN Circ. 18688) reported the position from GROND 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

XRT results are not available.

4. UVOT Observations and Analysis

The Swift/UVOT began observing the field of MAXI-detected GRB 151212A (De Pasquale and Evans GCN Circ. 18689) Nahakira et al., GCN Circ. 18685) 42183 s after the trigger. No optical afterglow consistent with the XRT source given by Evans et al. (GCN Circ. 18687) is detected in the UVOT exposures. 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 0.04 mag. in the direction of the GRB (Schlegel et al. 1998).

Figure 1. The BAT light curve is not available.

RA (J2000) Dec (J2000) Error Note Reference

04^h32^m36.50^s -03°57'41.3" 5.2" XRT Roegiers et al. GCN Circ. 18687

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Optical Wiseman et al. 18688 GROND Optical Afterglow Candidate GROND detection

Optical Kitaoka et al. 18725 iTelescope observation iTelescope

X-ray Nakahira et al. 18685 MAXI/GSC detection MAXI 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 42183 48392 2939 >21.4

RA (J2000)	Dec (J2000)	Error	Note	Reference
04^h32^m36.50^s	-03°57'41.3"	5.2"	XRT	Roegiers et al. GCN Circ. 18687

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Optical	Wiseman et al.	18688	GROND Optical Afterglow Candidate	GROND	detection
Optical	Kitaoka et al.	18725	iTelescope observation	iTelescope
X-ray	Nakahira et al.	18685	MAXI/GSC detection	MAXI	detection

Filter	T_start(s)	T_stop(s)	Exp(s)	Mag
u	42183	48392	2939	>21.4

Table 3. UVOT observation reported by De Pasquale and Evans (GCN Circ. 18689). The start and stop time of the exposure are given in seconds since the BAT trigger. The preliminary 3-σ upper limit is given. No correction has been made for extinction in the Milky Way.

December 27, 2015