Swift Observations of GRB 161010A

L.M. McCauley (PSU) and F.E. Marshall (NASA/GSFC) for the Swift team

1. Introduction

Mereghetti et al. (GCN Circ. 20021) reported the GRB detection. A gamma ray burst lasting about 30 s has been detected by IBAS in the IBIS/ISGRI data at 13:36:32 UT of 2016 October 10. Table 1 contains the best reported positions from Swift.

Marshall and D'Ai (GCN Circ. 20034) 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 refined results are not available.

4. UVOT Observations and Analysis

The Swift/UVOT began settled observations (Marshall and D'Ai GCN Circ. 20034) of the field of GRB 161010A 3.3 hours after the INTEGRAL trigger (Mereghetti et al., GCN Circ. 20021). A source consistent with the XRT position (McCauley et al., GCN Circ. 20025) 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 0.54 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
18h20m51.27s -28°47'06.7" UVOT-refined Marshall and D'Ai GCN Circ. 20034
18h20m51.44s -28°47'06.6" 2.9" XRT-final UKSSDC
18h20m51.44s -28°47'06.6" 2.9" XRT McCauley et al. GCN Circ. 20025

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes
Gamma-ray Mereghetti et al. 20021 a long GRB detected by INTEGRAL INTEGRAL
Gamma-ray Svinkin et al. 20027 Konus-Wind observation Konus-Wind Epeak=205 (-39,+56) keV
Duration=~22 seconds
Fluence=3.36(-0.38,+0.40)x10-5erg cm-2
Gamma-ray Yamaoka et al. 20033 CALET Gamma-Ray Burst Monitor detection CALET T90=4.9±0.5 seconds

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

Filter Tstart(s) Tstop(s) Exp(s) Mag
u 12034 13628 1035 18.8 ± 0.1
u 17802 19985 744 19.0 ± 0.1
u 23563 25993 794 19.4 ± 0.2
u 29338 30137 787 20.4 ± 0.4

Table 3. UVOT observations reported by Marshall and D'Ai (GCN Circ. 20034). 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.

October 14, 2016