Swift Observations of GRB 190110A

B. Sbarufatti (PSU) for the Swift team

1. Introduction

At 17:24:48 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 190110A (trigger=883012) (Sbarufatti et al. GCN Circ. 23670). Swift did not slew due to an observing constraint. At the time of the trigger, the initial BAT position was 34° from the Sun (1.0 hours West) and 67° from the 18%-illuminated Moon. 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.

Standard analysis products for this burst are available at https://gcn.gsfc.nasa.gov/swift_gnd_ana.html.

2. BAT Observations and Analysis

As reported by Ukwatta et al. (GCN Circ. 23674), the BAT ground-calculated position is RA, Dec = 276.939, -53.643 deg which is RA(J2000) = 18h27m45.3s Dec(J2000) = -53°38'34.3" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 43%.

The mask-weighted light curve (Figure 1) shows several overlapping peaks that starts at ~ T-1 s and ends at ~ T+11 s. The main peak occurs at ~T+5 s. T90 (15-350 keV) is 9.3 ± 0.8 s (estimated error including systematics).

The time-averaged spectrum from T-0.8 to T+11.0 s is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.66 ± 0.07. The fluence in the 15-150 keV band is 2.5 ± 0.1 x 10-6 erg cm-2. This fluence is larger than that of 67% of the long GRBs in the Second BAT GRB Catalog (Sakamoto et al. 2011). The 1-s peak photon flux measured from T+4.66 s in the 15-150 keV band is 9.0 ± 0.5 ph cm-2 s-1. All the quoted errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at https://gcn.gsfc.nasa.gov/notices_s/883012/BA/.

3. XRT Observations and Analysis

XRT refined results are not available.

4. UVOT Observations and Analysis

UVOT results are not available.

BAT light curve

Figure 1. The BAT mask-weighted light curve in the four individual and total energy bands. The units are counts s-1 illuminated-detector-1. The vertical green dash-dotted lines show the T50 interval, the vertical black dashed lines show the T90 interval, and vertical blue (orange) solid lines show the start (stop) of slews.

RA (J2000) Dec (J2000) Error Note Reference
18h27m45.3s -53°38'34.3" 1.0' BAT-refined Ukwatta et al. GCN Circ. 23674

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes
Gamma-ray Poolakkil and Meegan 23671 Fermi GBM detection Fermi GBM Epeak=73±8 keV
T90=9 seconds
Fluence=5.331±0.209x10-6erg cm-2
(58th percentile for long GRBs)
Gamma-ray Kozlova et al. 23675 Konus-Wind observation Konus-Wind Epeak=132 (-60,+111) keV
Duration=~5 seconds
Fluence=3.39(-0.51,+0.88)x10-6erg cm-2
Gamma-ray Luo et al. 23676 ：Insight-HXMT/HE detection Insight-HXMT T90=7.19 seconds

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

January 14, 2019