Swift Observations of GRB 190114C

J.D. Gropp (PSU), V. D'Elia (ASDC) and M.H. Siegel (PSU) for the Swift team

1. Introduction

At 20:57:03 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 190114C (trigger=883832) (Gropp et al. GCN Circ. 23688). Swift slewed immediately to the burst. At the time of the trigger, the initial BAT position was 103° from the Sun (7.9 hours East) and 41° from the 56%-illuminated Moon. Table 1 contains the best reported positions from Swift, and the latest XRT position can be viewed at http://www.swift.ac.uk/xrt_positions.

Gropp et al. (GCN Circ. 23688) reported the discovery with UVOT of an optical afterglow. Tyurina et al. (GCN Circ. 23690) reported the position from MASTER for the optical afterglow of this GRB. Selsing et al. (GCN Circ. 23695) determined a redshift of 0.42 from NOT, and Castro-Tirado. Y. Hu et al. (GCN Circ. 23708) determined a redshift of 0.4245 from GTC. 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 Krimm et al. (GCN Circ. 23724), the BAT ground-calculated position is RA, Dec = 54.503, -26.938 deg which is RA(J2000) = 03^h38^m00.7^s Dec(J2000) = -26°56'17.5" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%.

The mask-weighted light curve (Figure 1) shows a multi-peaked structure that starts at ~T-7 s. The brightest emission contains two complex pulses and ends at ~T+50 s. Afterwards, the emission appeared to decay exponentially out to beyond ~T+720 s, when the burst went out of the BAT field of view. The burst did not come back into the BAT field of view until ~T+3800, and nothing significant was detected at that time. T₉₀ (15-350 keV) estimated using data before the burst went out of the BAT field of view is 361.5 ± 11.7 s (estimated error including systematics). Please note that this T₉₀ might be an underestimate.

The time-averaged spectrum from -6.604 to 703.192 s is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.43 ± 0.02. The fluence in the 15-150 keV band is 8.3 ± 0.1 x 10^-5 erg cm^-2. This fluence is larger than that of 99.5% of the long GRBs in the Second BAT GRB Catalog (Sakamoto et al. 2011). The 1-s peak photon flux measured from T+0.23 s in the 15-150 keV band is 101.0 ± 1.5 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/883832/BA/.

3. XRT Observations and Analysis

Analysis of the initial XRT data was reported by D'Elia et al. (GCN Circ. 23706). We have analysed 116 ks of XRT data for GRB 190114C, from 58 s to 2477.6 ks after the BAT trigger. The data comprise 1.0 ks in Windowed Timing (WT) mode (the first 4 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 23704).

The light curve (Figure 2) can be modelled with a series of power-law decays. The initial decay index is α=1.367 ± 0.025. At T+361 s the decay steepens to an α of 1.81 (+0.60, -0.19). The light curve breaks again at T+449 s to a decay with α=1.216 (+0.019, -0.017), and again at T+5520 s s to α=8.0 (+0.0, -4.4), before a final break at T+5649 s s after which the decay index is 1.464 (+0.025, -0.023).

A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.66 ± 0.04. The best-fitting absorption column is 8.19 (+0.24, -0.23) x 10²² cm^-2, at a redshift of 0.42, in addition to the Galactic value of 7.5 x 10¹⁹ cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.81 (+0.11, -0.10) and a best-fitting absorption column of 7.7 ± 0.6 x 10²² cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 7.6 x 10^-11 (1.6 x 10^-10) erg cm^-2 count^-1.

A summary of the PC-mode spectrum is thus:
Galactic foreground: 7.5 x 10¹⁹ cm^-2
Intrinsic column: 7.7 ± 0.6 x 10²² cm^-2 at z=0.42
Photon index: 1.81 (+0.11, -0.10)

The results of the XRT team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00883832.

4. UVOT Observations and Analysis

The Swift/UVOT began settled observations of the field of GRB 190114C 74 s after the BAT trigger (Siegel and Gropp GCN Circ. 23725). A source consistent with the XRT position (Osborne et al. GCN Circ. 23704) and previously reported optical detections (Tyurina et al., GCN Circ. 23690, Selsing et al., GCN Circ. 23695, Izzy et al., GCN Circ. 23699, Bolmer & Schady, GCN Circ. 23702, Im et al., GCN Circ. 23717) 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 E_B-V of 0.01 mag. in the direction of the GRB (Schlegel et al. 1998).

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.

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

03^h38^m01.16^s -26°56'46.9" 0.42" UVOT-refined Siegel and Gropp GCN Circ. 23725

03^h38^m01.18^s -26°56'47.8" 1.4" XRT-final UKSSDC

03^h38^m01.20^s -26°56'47.6" 1.4" XRT-enhanced Osborne et al. GCN Circ. 23704

03^h38^m00.7^s -26°56'17.5" 1.0' BAT-refined Krimm et al. GCN Circ. 23724

Table 1. Positions from the Swift instruments.

Band Authors GCN Circ. Subject Observatory Notes

Optical Tyurina et al. 23690 MASTER afterglow Detection MASTER detection

Optical de Ugarte Postigo et al. 23692 Possible host galaxy in Pan-STARRS Pan-STARRS

Optical Lipunov et al. 23693 MASTER 4-polarizations filters OT
detection MASTER detection

Optical Selsing et al. 23695 NOT optical counterpart and redshift NOT redshift

Optical Izzo et al. 23699 OASDG optical observations S.Di Giacomo Obs. detection

Optical Bolmer and Schady 23702 GROND detection of the afterglow GROND detection

Optical Castro-Tirado. Y. Hu et al. 23708 refined redshift by the 10.4m GTC GTC redshift

Optical Kann et al. 23710 X-shooter observations of a highly
extinguished afterglow X-shooter

Optical Im et al. 23717 Optical observations

Optical Mazaeva et al. 23727 Mondy optical observations Mondy

Optical D'Avanzo et al. 23729 REM optical/NIR detection REM detection

Optical Kim and Im 23732 LSGT optical observation Lee Sang Gak Telescope

Optical Kumar et al. 23733 GRowth-India detection of optical
afterglow GROWTH-India detection

Optical Kim et al. 23734 KMTNet optical observation

Optical Im et al. 23740 UKIRT JHK observation UKIRT detection

Optical Mazaeva et al. 23741 CHILESCOPE optical observations detection

Optical Kumar et al. 23742 Optical detection from HCT Himalayan Chandra Telescope detection

Optical Mazaeva et al. 23746 continued CHILESCOPE optical obs detection

Optical Im et al. 23747 Continued UKIRT JHK observation UKIRT

Optical Ragosta et al. 23748 ePESSTO NTT optical observations PESSTO detection

Optical Watson et al. 23749 COATLI Optical Detection COATLI detection

Optical Watson et al. 23751 RATIR Optical and NIR Detections RATIR detection

Optical D'Avanzo 23754 REM optical/NIR detection (CORRECTION) REM detection

Optical Im et al. 23756 UKIRT JHK observation continuation -
steady fading? UKIRT

Optical Im et al. 23757 UKIRT JHK observation (CORRECTIONS) UKIRT

Optical Bikmaev et al. 23766 RTT150 optical observations RTT150 detection

Optical Mazaeva et al. 23787 CHILESCOPE optical observations detection

Optical Singh et al. 23798 Optical follow-up from HCT Himalayan Chandra Telescope detection

Radio Alexander et al. 23726 VLA Detection VLA detection

Radio Laskar et al. 23728 ALMA detection of a fading mm
counterpart ALMA detection

Radio Schulze et al. 23745 ATCA detection of the radio afterglow ATCA detection

Radio Volvach et al. 23750 RT-22 detection at 36.8 GHz CrAO RT-22 detection

Radio Marongiu et al. 23753 Sardinia Radio Telescope observations

Radio Marongiu 23755 Sardinia Radio Telescope observations
(CORRECTION)

Radio Tremou et al. 23760 MeerKAT radio observation detection

Radio Cherukuri et al. 23762 GMRT detection at 1.26GHz GMRT detection

Radio Smith et al. 23823 JCMT SCUBA-2 sub-mm observations SCUBA

X-ray 23698 #: Planned XMM-Newton observation XMM plans

X-ray 23700 CORRECTED TARGET NAME: GRB 190114C:
Planned XMM-Newton observation XMM plans

Gamma-ray Mirzoyan and Noda 23701 MAGIC detects the GRB 190114C in the
TeV energy domain MAGIC

Gamma-ray Hamburg et al. 23707 Fermi GBM detection Fermi GBM E_peak=998.6±11.9 keV
T₉₀=116 seconds

Gamma-ray Kocevski et al. 23709 Fermi-LAT detection Fermi LAT E_max=22.9 GeV

Gamma-ray Ursi et al. 23712 AGILE/MCAL detection AGILE

Gamma-ray Minaev and Pozanenko 23714 SPI-ACS/INTEGRAL extended emission
detection INTEGRAL

Gamma-ray Xiao et al. 23716 Insight-HXMT/HE detection Insight-HXMT T₉₀=15.68 seconds

Gamma-ray Frederiks et al. 23737 Konus-Wind observation Konus-Wind E_peak=646 (-16,+16) keV

Other Ruffini et al. 23715 A type 1 BdHN with TeV emission

Other Dado 23735 Long follow up urged light curve

Other Melandri et al. 23983 photometric detection of a SN component

Other Giroletti et al. 24766 East Asia VLBI Network observations

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

Filter T_start(s) T_stop(s) Exp(s) Mag

white (fc) 74 224 147 14.89±0.02

white 566 586 19 16.90±0.07

white 5851 6050 196 19.19±0.09

white 21950 22857 885 20.22±0.09

v 616 627 10 16.28±0.19

v 16295 17136 820 18.97±0.13

v 26775 27682 885 19.41±0.24

v 39149 57221 1694 19.92±0.20

b 542 561 19 17.38±0.14

b 5646 5845 196 19.38±0.16

b 21038 46521 1591 20.83±0.26

u (fc) 286 536 245 17.58±0.07

u 33738 34038 295 >20.28

uvw1 4044 51522 3671 21.05±0.31

uvm2 3839 50615 3251 21.00±0.30

uvw2 6056 56384 3552 >21.33

RA (J2000)	Dec (J2000)	Error	Note	Reference
03^h38^m01.16^s	-26°56'46.9"	0.42"	UVOT-refined	Siegel and Gropp GCN Circ. 23725
03^h38^m01.18^s	-26°56'47.8"	1.4"	XRT-final	UKSSDC
03^h38^m01.20^s	-26°56'47.6"	1.4"	XRT-enhanced	Osborne et al. GCN Circ. 23704
03^h38^m00.7^s	-26°56'17.5"	1.0'	BAT-refined	Krimm et al. GCN Circ. 23724

Band	Authors	GCN Circ.	Subject	Observatory	Notes
Optical	Tyurina et al.	23690	MASTER afterglow Detection	MASTER	detection
Optical	de Ugarte Postigo et al.	23692	Possible host galaxy in Pan-STARRS	Pan-STARRS
Optical	Lipunov et al.	23693	MASTER 4-polarizations filters OT detection	MASTER	detection
Optical	Selsing et al.	23695	NOT optical counterpart and redshift	NOT	redshift
Optical	Izzo et al.	23699	OASDG optical observations	S.Di Giacomo Obs.	detection
Optical	Bolmer and Schady	23702	GROND detection of the afterglow	GROND	detection
Optical	Castro-Tirado. Y. Hu et al.	23708	refined redshift by the 10.4m GTC	GTC	redshift
Optical	Kann et al.	23710	X-shooter observations of a highly extinguished afterglow	X-shooter
Optical	Im et al.	23717	Optical observations
Optical	Mazaeva et al.	23727	Mondy optical observations	Mondy
Optical	D'Avanzo et al.	23729	REM optical/NIR detection	REM	detection
Optical	Kim and Im	23732	LSGT optical observation	Lee Sang Gak Telescope
Optical	Kumar et al.	23733	GRowth-India detection of optical afterglow	GROWTH-India	detection
Optical	Kim et al.	23734	KMTNet optical observation
Optical	Im et al.	23740	UKIRT JHK observation	UKIRT	detection
Optical	Mazaeva et al.	23741	CHILESCOPE optical observations		detection
Optical	Kumar et al.	23742	Optical detection from HCT	Himalayan Chandra Telescope	detection
Optical	Mazaeva et al.	23746	continued CHILESCOPE optical obs		detection
Optical	Im et al.	23747	Continued UKIRT JHK observation	UKIRT
Optical	Ragosta et al.	23748	ePESSTO NTT optical observations	PESSTO	detection
Optical	Watson et al.	23749	COATLI Optical Detection	COATLI	detection
Optical	Watson et al.	23751	RATIR Optical and NIR Detections	RATIR	detection
Optical	D'Avanzo	23754	REM optical/NIR detection (CORRECTION)	REM	detection
Optical	Im et al.	23756	UKIRT JHK observation continuation - steady fading?	UKIRT
Optical	Im et al.	23757	UKIRT JHK observation (CORRECTIONS)	UKIRT
Optical	Bikmaev et al.	23766	RTT150 optical observations	RTT150	detection
Optical	Mazaeva et al.	23787	CHILESCOPE optical observations		detection
Optical	Singh et al.	23798	Optical follow-up from HCT	Himalayan Chandra Telescope	detection
Radio	Alexander et al.	23726	VLA Detection	VLA	detection
Radio	Laskar et al.	23728	ALMA detection of a fading mm counterpart	ALMA	detection
Radio	Schulze et al.	23745	ATCA detection of the radio afterglow	ATCA	detection
Radio	Volvach et al.	23750	RT-22 detection at 36.8 GHz	CrAO RT-22	detection
Radio	Marongiu et al.	23753	Sardinia Radio Telescope observations
Radio	Marongiu	23755	Sardinia Radio Telescope observations (CORRECTION)
Radio	Tremou et al.	23760	MeerKAT radio observation		detection
Radio	Cherukuri et al.	23762	GMRT detection at 1.26GHz	GMRT	detection
Radio	Smith et al.	23823	JCMT SCUBA-2 sub-mm observations	SCUBA
X-ray		23698	#: Planned XMM-Newton observation	XMM	plans
X-ray		23700	CORRECTED TARGET NAME: GRB 190114C: Planned XMM-Newton observation	XMM	plans
Gamma-ray	Mirzoyan and Noda	23701	MAGIC detects the GRB 190114C in the TeV energy domain	MAGIC
Gamma-ray	Hamburg et al.	23707	Fermi GBM detection	Fermi GBM	E_peak=998.6±11.9 keV T₉₀=116 seconds
Gamma-ray	Kocevski et al.	23709	Fermi-LAT detection	Fermi LAT	E_max=22.9 GeV
Gamma-ray	Ursi et al.	23712	AGILE/MCAL detection	AGILE
Gamma-ray	Minaev and Pozanenko	23714	SPI-ACS/INTEGRAL extended emission detection	INTEGRAL
Gamma-ray	Xiao et al.	23716	Insight-HXMT/HE detection	Insight-HXMT	T₉₀=15.68 seconds
Gamma-ray	Frederiks et al.	23737	Konus-Wind observation	Konus-Wind	E_peak=646 (-16,+16) keV
Other	Ruffini et al.	23715	A type 1 BdHN with TeV emission
Other	Dado	23735	Long follow up urged		light curve
Other	Melandri et al.	23983	photometric detection of a SN component
Other	Giroletti et al.	24766	East Asia VLBI Network observations

Filter	T_start(s)	T_stop(s)	Exp(s)	Mag
white (fc)	74	224	147	14.89±0.02
white	566	586	19	16.90±0.07
white	5851	6050	196	19.19±0.09
white	21950	22857	885	20.22±0.09
v	616	627	10	16.28±0.19
v	16295	17136	820	18.97±0.13
v	26775	27682	885	19.41±0.24
v	39149	57221	1694	19.92±0.20
b	542	561	19	17.38±0.14
b	5646	5845	196	19.38±0.16
b	21038	46521	1591	20.83±0.26
u (fc)	286	536	245	17.58±0.07
u	33738	34038	295	>20.28
uvw1	4044	51522	3671	21.05±0.31
uvm2	3839	50615	3251	21.00±0.30
uvw2	6056	56384	3552	>21.33

Table 3. UVOT observations reported by Siegel and Gropp (GCN Circ. 23725). 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.

June 7, 2019