Swift Observations of GRB 200826A

A. D'Ai (INAF-IASFPA) for the Swift team

1. Introduction

Hurley et al. (GCN Circ. 28291) 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

Analysis of the initial XRT data was reported by D'Ai et al. (GCN Circ. 28300). Source 3 is fading with 3-sigma significance, and is therefore likely the GRB afterglow.

The light curve (Figure 2) can be modelled with a power-law decay with a decay index of α=1.3 (+0.7, -0.5).

A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.8 (+0.6, -0.5). The best-fitting absorption column is 2.2 (+2.5, -1.6) x 10²¹ cm^-2, consistent with the Galactic value of 6.0 x 10²⁰ cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1.

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

00^h27^m08.32^s +34°01'36.1" 3.3" XRT D'Ai et al. GCN Circ. 28300

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Optical Lipunov et al. 28285 Fermi GRB 200826A: Global MASTER-Net
observations report MASTER

Optical Ahumada et al. 28295 Zwicky Transient Facility Identifies
Optical Afterglow Candidate of a Fermi
Short GRB (Trigger 620108997) detection

Optical Belkin et al. 28306 Kitab optical observations

Optical Rossi et al. 28949 TNG and LBT constraints on a supernova
bump LBT detection

Radio Alexander et al. 28302 VLA Detection at 6 GHz VLA detection

Radio Chandra et al. 28410 uGMRT radio upper limit at 1.25 GHz GMRT upper limits

Gamma-ray Fermi 28284 Fermi GBM Final Real-time Localization Fermi GBM

Gamma-ray Kunzweiler et al. 28286 BALROG localization (Fermi Trigger
620108997 / GRB 200826187) BALROG

Gamma-ray Mangan et al. 28287 Fermi GBM observation Fermi GBM E_peak=89.8±3.7 keV
T₉₀=1.14 seconds
Fluence=4.8±0.1x10^-6erg cm^-2
(97 percentile for short GRBs)

Gamma-ray Gupta et al. 28288 AstroSat CZTI detection CZTI

Gamma-ray Pittori et al. 28289 AGILE detection AGILE

Gamma-ray Hurley et al. 28291 IPN triangulation of GRB 200826A
(short/bright) IPN

Gamma-ray Ridnaia et al. 28294 Konus-Wind detection Konus-Wind E_peak=67 (-17,+31) keV
Duration=~1.6 seconds
Fluence=3.30(-0.42,+0.47)x10^-6erg cm^-2

Gamma-ray Svinkin et al. 28301 further analysis of the Konus-Wind data
and classification Konus-Wind

Other Carracedo et al. 28293 Zwicky Transient Facility Follow-Up of
a Fermi Short GRB (Trigger 620108997)

Other Dichiara et al. 28312 Lowell Discovery Telescope observations
of ZTF20abwysqy

Other Rothberg et al. 28319

Other Ahumada et al. 28727 GMOS-N detection of a supernova bump

Other Ahumada et al. 29029 GMOS-N detected source magnitude
(Correction) detection

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

RA (J2000)	Dec (J2000)	Error	Note	Reference
00^h27^m08.32^s	+34°01'36.1"	3.3"	XRT	D'Ai et al. GCN Circ. 28300

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Optical	Lipunov et al.	28285	Fermi GRB 200826A: Global MASTER-Net observations report	MASTER
Optical	Ahumada et al.	28295	Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi Short GRB (Trigger 620108997)		detection
Optical	Belkin et al.	28306	Kitab optical observations
Optical	Rossi et al.	28949	TNG and LBT constraints on a supernova bump	LBT	detection
Radio	Alexander et al.	28302	VLA Detection at 6 GHz	VLA	detection
Radio	Chandra et al.	28410	uGMRT radio upper limit at 1.25 GHz	GMRT	upper limits
Gamma-ray	Fermi	28284	Fermi GBM Final Real-time Localization	Fermi GBM
Gamma-ray	Kunzweiler et al.	28286	BALROG localization (Fermi Trigger 620108997 / GRB 200826187)	BALROG
Gamma-ray	Mangan et al.	28287	Fermi GBM observation	Fermi GBM	E_peak=89.8±3.7 keV T₉₀=1.14 seconds Fluence=4.8±0.1x10^-6erg cm^-2 (97 percentile for short GRBs)
Gamma-ray	Gupta et al.	28288	AstroSat CZTI detection	CZTI
Gamma-ray	Pittori et al.	28289	AGILE detection	AGILE
Gamma-ray	Hurley et al.	28291	IPN triangulation of GRB 200826A (short/bright)	IPN
Gamma-ray	Ridnaia et al.	28294	Konus-Wind detection	Konus-Wind	E_peak=67 (-17,+31) keV Duration=~1.6 seconds Fluence=3.30(-0.42,+0.47)x10^-6erg cm^-2
Gamma-ray	Svinkin et al.	28301	further analysis of the Konus-Wind data and classification	Konus-Wind
Other	Carracedo et al.	28293	Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 620108997)
Other	Dichiara et al.	28312	Lowell Discovery Telescope observations of ZTF20abwysqy
Other	Rothberg et al.	28319
Other	Ahumada et al.	28727	GMOS-N detection of a supernova bump
Other	Ahumada et al.	29029	GMOS-N detected source magnitude (Correction)		detection

December 12, 2020