Swift Observations of GRB 140226A

A.P. Beardmore (U. Leicester) and M.H. Siegel (PSU) for the Swift team

1. Introduction

Hurley et al. (GCN Circ. 15888) reported the GRB detection. Table 1 contains the best reported positions from Swift.

Cenko et al. (GCN Circ. 15883) reported the position from iPTF 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

Analysis of the UVOT data was reported by Siegel et al. (GCN Circ. 15894). Swift/UVOT started observations of GRB140226A/iPTF14yb (Cenko et al., GCN Circ. 15833) 25718 s after the IPN trigger (Hurley et al., GCN Circ. 15888). No optical counterpart is detected at the position of the iPTF or XRT positions (Beardmore et al., GCN Circ. 15884) in summed 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 EB-V of 0.02 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 cross-hatched region are not included in the fit.

RA (J2000) Dec (J2000) Error Note Reference
14h45m58.06s +14°59'38.5" 3.9" XRT-final UKSSDC
14h45m58.03s +14°59'38.3" 3.7" XRT Beardmore et al. GCN Circ. 15884

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes
Optical Cenko et al. 15883 iPTF14yb: iPTF Discovery of an Optical
Afterglow-like Transient		 iPTF detection
Optical Cucchiara et al. 15886 iPTF14yb: RATIR Optical and NIR
Observations of the optical transient		 RATIR detection
Optical Varela et al. 15887 PTF14yb: GROND Transient Detection GROND detection
Optical Hurley et al. 15888 IPN triangulation of GRB 140226A, a
possible GRB counterpart to iPTF14yb		 iPTF possible detection
Optical Cucchiara et al. 15892 iPTF14yb: RATIR Optical and NIR
Observations		 RATIR detection
Optical Volnova et al. 15893 iPTF14yb: Mondy optical observations Mondy
Optical Gorosabel et al. 15895 iPTF14yb: 1.23m CAHA observations CAHA
Optical Volnova et al. 16037 iPTF14yb: Mondy optical observations Mondy
Gamma-ray Golenetskii et al. 15889 Konus-Wind observation Konus-Wind Epeak=414±79 keV
Fluence=5.6±1.1x10-6erg cm-2

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

Filter Tstart(s) Tstop(s) Exp(s) Mag
uvm2 25718 43672 2180 >21.24
v 124093 136265 4877 >20.96
v 147705 154552 1822 >20.54

Table 3. UVOT observations reported by Siegel et al. (GCN Circ. 15894). The start and stop times of the exposures are given in seconds since the BAT trigger. The preliminary 3-σ upper limits are given. No correction has been made for extinction in the Milky Way.

March 26, 2014