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Observation Date (UT) Observation Lat

Canonical Name:GRB 190114C
TeVCat Name:TeV J0338-269
Other Names:
Source Type:GRB
R.A.:03 38 01.17 (hh mm ss)
Dec.:-26 56 46.73 (dd mm ss)
Gal Long: 222.47 (deg)
Gal Lat: -53.08 (deg)
Distance: z=0.4245
Flux: (Crab Units)
Energy Threshold:300 GeV
Spectral Index:
Extended:No
Discovery Date:2019-01
Discovered By: MAGIC
TeVCat SubCat:Default Catalog

Source Notes:

Overview of the Detection:
From MAGIC Collaboration (2019):
- "Gamma-rays were observed in the energy range 0.2-1 teraelectronvolt
from about one minute after the burst (at more than 50 standard
deviations in the first 20 minutes), revealing a distinct emission
component of the afterglow with power comparable to that of the
synchrotron component."
- "The observed similarity in the radiated power and temporal
behaviour of the teraelectronvolt and X-ray bands points to processes
such as inverse Compton upscattering as the mechanism of the
teraelectronvolt emission"
- "Triggered by the Swift-BAT alert, the Major Atmospheric Gamma
Imaging Cherenkov (MAGIC) telescopes observed GRB 190114C from:
T0 + 57s until T0 + 15,912 s"

MAGIC have detected sub-TeV emission from GRB 190114C:
An extract from their ATel:
- "The MAGIC telescopes performed a rapid follow-up observation of GRB 190114C
(Gropp et al., GCN 23688; Tyurina et al., GCN 23690,
de Ugarte Postigo et al., GCN 23692, Lipunov et al. GCN 23693,
Selsing et al. GCN 23695). This observation was triggered by the
Swift-BAT alert; we started observing at about 50s after Swift T0:
20:57:03.19. The MAGIC real-time analysis shows a significance >20
sigma in the first 20 min of observations (starting at T0+50s) for
energies >300GeV. The relatively high detection threshold is due to
the large zenith angle of observations (>60 degrees) and the presence
of partial Moon. Given the brightness of the event, MAGIC will
continue the observation of GRB 190114C until it is observable tonight
and also in the next days. We strongly encourage follow-up
observations by other instruments."

GRB Parameters:
From MAGIC Collaboration (2019):
- A long GRB: "GRB 190114C was first identified as a long-duration GRB
by the Burst Alert Telescope (BAT) onboard the Neil Gehrels Swift
Observatory (Swift) and the Gamma-ray Burst Monitor (GBM) instrument
onboard the Fermi satellite"

- T0: 14 January 2019, 20:57:03 (UT)

- T90: "Its duration in terms of T90 (the time interval containing 90%
of the total photon counts) was measured to be about 116 s by
Fermi-GBM and about 362 s by Swift-BAT"

Source Position:
The GRB position quoted is that from Tyurina et al. (2019):
- R.A. (J2000): 03h 38m 01.17s
- Dec. (J2000): -26d 56m 46.73s

Distance:
From Castro-Tirado et al. (2019):
- "Following the detection of the ultra-bright GRB 190114C ... optical
spectroscopy of the reported optical afterglow has been undertaken at
the 10.4m GTC telescope (+OSIRIS) at the Spanish island of La Palma
starting on Jan 14, 23:32 UT (2.6 hr post-burst). The two spectra
(600s each, at high airmass) covered the range 3,700-9.600 A and the
detection of Ca H & K lines and the Na I doublet (as well as other
Fraunhofer lines) confirms the redshift value reported by Selsing et al.
which we refine to z = 0.4245 +/- 0.0005, supporting
the association with the galaxy detected in the Pan-STARRS archival
data (de Ugarte Postigo et al.)."

From Selsing et al. (2019):
- "We immediately followed up with spectroscopic observations using
the Alfosc instrument, in which the afterglow is very clearly
detected. From the detection of strong absorption lines from Ca H & K
along with Na ID in the afterglow spectrum, we derive a redshift of z = 0.42,
which we suggest is the redshift of the GRB."

Spectral Properties:
From MAGIC Collaboration (2019):
- "The observed spectrum can be fitted in the energy range 0.2–1 TeV
with a simple power law with photon index:
... A_obs = 5.43 +/- 0.22 (statistical error only),
one of the steepest spectra ever observed for a gamma-ray source. It
is remarkable that photons are observed at Energy of approx. 1 TeV,
despite the severe EBL attenuation expected at these energies (by a
factor of about 300, according to plausible EBL models"
- The spectrum was derived by assuming a simple power-law spectrum for
the intrinsic spectrum of the form: dF/dE = F0 x (E/E0)^-A
- The EBL model of Dominguez et al. (2011) was used to
de-absorb the measured spectrum to determine the intrinsic spectral
parameters:
- A_int: 2.22 +0.23 (stat) -0.25 (stat) +0.21 (syst) -0.25 (syst)
- F0_int: 8.45 +0.68 (stat) -0.65 (stat) +4.42 (syst) -3.97 (syst) x10e-9 TeV-1 cm-2 s-1
- E0: 0.46 TeV
- the authors report that "there is no significant evidence for spectral variability"
From MAGIC Collaboration et al. (2019):
- "Here we report multi-frequency observations of GRB 190114C, and
study the evolution in time of the GRB emission across 17 orders of
magnitude in energy, from 5 x 10e−6 to 10e12 electronvolts."
- "We find that the broadband spectral energy distribution is
double-peaked, with the teraelectronvolt emission constituting a
distinct spectral component with power comparable to the synchrotron
component."
- "This component is associated with the afterglow and is
satisfactorily explained by inverse Compton up-scattering of
synchrotron photons by high-energy electrons."
- "We find that the conditions required to account for the observed
teraelectronvolt component are typical for GRBs, supporting the
possibility that inverse Compton emission is commonly produced in
GRBs."

Temporal Evolution:
From MAGIC Collaboration (2019):
- the light curve of the GRB "is well fitted with a simple power-law
function F(t) proportional to tB with:
... B = -1.60 +/-0.07.
The flux evolves from:
... F(t) approx. 5 × 10e-8 erg cm-2 s-1 at t approx. T0 +80s
to
... F(t) approx. 6 × 10e-10 erg cm-2 s-1 at t greater/equal than T0 + 103 s
... after which it falls below the sensitivity level of the telescopes
and is undetectable. There is no clear evidence for breaks or cutoffs
in the light curve, nor irregular variability beyond the monotonic
decay. The light curves in the kiloelectronvolt and gigaelectronvolt
bands display behaviour similar to the teraelec- tronvolt band, with a
somewhat shallower decay slope for the gigaelectronvolt band."
- "These properties indicate that most of the observed emission is
associated with the afterglow phase, rather than the prompt phase,
which typically shows irregular variability. "

Fermi-LAT Detection:
From Axelsson et al. (2019):
- "The data from the Fermi-LAT show a significant increase in the
event rate that is spatially correlated with the GBM trigger with high
significance. The highest-energy photon is a 22.9 GeV event which is
observed 15 s after the GBM trigger.
- The estimated photon index above 100 MeV is -1.98 +/- 0.06, with an
estimated photon and energy flux of 2.69e-03 +/- 1.86e-04 ph/cm2/s and
2.06e-06 +/- 1.42e-07 erg/cm2/s, respectively."


Seen by: MAGIC
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