Swift Observations of GRB 150902A

L.M. McCauley (PSU) and A.A. Breeveld (UCL-MSSL) for the Swift team

1. Introduction

Arimoto et al. (GCN Circ. 18228) reported the GRB detection. Table 1 contains the best reported positions from Swift.

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 (Breeveld and Hagen GCN Circ. 18238) of the field of GRB 150902A 59510 s after the LAT trigger (Arimoto et al., GCN Circ. 18228). No optical afterglow consistent with the XRT Source 1 position given in McCauley et al. (GCN Circ. 18237) is detected in the initial 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 EB-V of 0.40 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
14h19m55.09s -69°21'13.1" 4.3" XRT McCauley et al. GCN Circ. 18243

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes
Optical Buckley et al. 18234 MASTER-SAAO optical observations Abastumani Astro. Obs.
Gamma-ray Arimoto et al. 18228 Fermi-LAT detection Fermi LAT Emax=11 GeV
Gamma-ray Roberts and Younes 18229 Fermi GBM detection Fermi GBM Epeak=351.40±5.61 keV
Fluence=8.221±0.043x10-5erg cm-2
Gamma-ray Golenetskii et al. 18233 Konus-Wind observation Konus-Wind Fluence=1.21(-0.07,+0.07)x10-4erg 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
white 60331 60972 631 >21.7
v 61152 61997 828 >20.3
u 59510 66787 1184 >20.7

Table 3. UVOT observations reported by Breeveld and Hagen (GCN Circ. 18238). 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.

September 6, 2015