Swift Observations of GRB 200914A

M. Perri (ASDC) for the Swift team

1. Introduction

Mereghetti et al. (GCN Circ. 28419) reported the GRB detection. A gamma ray burst lasting about 70 s has been detected by IBAS in the IBIS/ISGRI data at 12:48:30 UT of 2020 September 14. 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

Analysis of the initial XRT data was reported by D’Avanzo et al. (GCN Circ. 28466). The only uncatalogued source in the field, Source 1 (Perri et al., GCN Circ. 28425), is not detected anymore down to a 3sigma count rate limit of 2.1 x 10^-3 ct s^-1. From a re-analysis of the first XRT observation, consisting in 1.2 ks of data collected between T+9.0 ks and T+10.2 ks, we measure a count rate of 6.6 x 10^-3 (+3.3 x 10^-3, -2.5 x 10^-3) ct s^-1. Although there is moderate evidence for fading between these two epochs, we cannot exclude that the observed X-ray emission is coming from the bright IR source reported in Perri et al. (GCN Circ. 28425), possibly unrelated to GRB 200914A.

4. UVOT Observations and Analysis

UVOT results are not available.

Figure 1. The BAT light curve is not available.

RA (J2000)	Dec (J2000)	Error	Note	Reference

Table 1. Positions from the Swift instruments.

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Optical	Lipunov et al.	28427	Fermi GRB 200914A: Global MASTER-Net observations report	MASTER
Optical	Lipunov et al.	28428	Integral GRB200914.53: Global MASTER-Net observations report	MASTER
Gamma-ray	Fermi	28417	Fermi GBM Final Real-time Localization	Fermi GBM
Gamma-ray	Kunzweiler et al.	28418	BALROG localization (Fermi Trigger 621780515 / GRB 200914534)	BALROG
Gamma-ray	Mereghetti et al.	28419	A long GRB detected by INTEGRAL	INTEGRAL	Fluence=3x10-6erg cm-2
Gamma-ray	Dunwoody et al.	28424	Fermi GBM observation	Fermi GBM	Epeak=1260±140 keV T90=65 seconds Fluence=9.80±0.71x10-5erg cm-2 (97.8 percentile for long GRBs)
Gamma-ray	Ursi et al.	28426	AGILE detection	AGILE
Gamma-ray	Tsvetkova et al.	28495	Konus-Wind observation	Konus-Wind	Epeak=461 (-128,+201) keV Fluence=4.26(-0.96,+1.08)x10-5erg cm-2

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

September 26, 2020