GRB 190519A

A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks,
M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 190519A
(Fermi GBM observation: Fermi GBM team, GCN 24594
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 ; von Kienlin, GCN 24596
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 ;
Swift detection: Ukwatta et al., GCN 24595
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 ; Lien et al., GCN 24606
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 ;
CALET Gamma-Ray Burst Monitor detection: Yamaoka et al., GCN 24611
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 ;
AstroSat CZTI detection: Ghumatkar et al., GCN 24613
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 )
triggered Konus-Wind at T0=26732.082 s UT (07:25:32.082).

The burst light curve shows two pulses.
The first one starts at T0-39.0 s and ends at T0-3.7 s.
The second, bright, double-peaked pulse starts at T0-3.7 s and ends at 
T0+11.6 s.
The total duration of the burst is ~51 s.
The emission is seen up to ~1.5 MeV.

As observed by Konus-Wind, the burst
had a fluence of 3.20(-0.16,+0.18)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+6.752 s,
of 5.80(-1.01,+1.01)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the main pulse
(measured from T0 to T0+15.616 s)
is best fit in the 20 keV - 1.5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with�� alpha = -1.05(-0.09,+0.10),
and Ep = 125(-6,+7) keV (chi2 = 67/60 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -3.05 (chi2 = 67/59 dof).

The spectrum near the peak count rate
(measured from T0+0.256 to T0+7.424 s)
is best fit in the 20 keV - 1.5 MeV range
by the power law with exponential cutoff model
with�� alpha = -0.93(-0.10,+0.10),
and Ep = 136(-6,+7) keV (chi2 = 65/60 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.96 (chi2 = 64/59 dof).

Modeling the K-W 3-channel spectrum of the initial pulse
(measured from T0-38.980 s to T0-3.652 s)
by a simple power law yields the photon index of 2.21(-0.07,+0.08),
chi2 = 0.94/1 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB190519_T26732/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.

P. Ghumatkar, V. Sharma, T. Khanam, D. Bhattacharya and A. Vibhute (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed the detection of a long GRB 190519A, which was also detected by Fermi GBM (GCN #24594
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 ).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple pulses of emission with the strongest peak at 07:25:43 UT. The measured peak count rate associated with the burst is 185 cts/s above the background in the combined data of four quadrants, with a total of 706 cts. The local mean background count rate was 622 cts/s. Using cumulative rates, we measure a T90 of 45.2 s. In preliminary analysis, we find that 429 Compton events are associated with this event.

It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.

J. D. Gropp (PSU) and T. N. Ukwatta (LANL)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 190519A
150 s after the BAT trigger (Ukwatta et al., GCN Circ. 24595
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 ).
No optical afterglow consistent with the enhanced XRT position
(Ukwatta et al. GCN Circ. 24597
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 )
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

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

u_FC               150          400          246         >18.9
v                  456         2571          272         >18.7
b                  406         2520          272         >19.7
u                  150         2495          646         >19.5
w1                 505         2610          262         >19.5
m2                 481         2595          272         >19.1
w2                 432         2546          272         >19.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.42 in the direction of the burst
(Schlegel et al. 1998).

K. Yamaoka (Nagoya U),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), S. Nakahira (RIKEN),
Y. Asaoka, S. Ozawa, S. Torii (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long bright GRB 190519A (Swift-BAT trigger #904394: Ukwatta et al.,
GCN Circ. 24595
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 , Lien et al., GCN Circ. 24606
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 ; Fermi GBM observation:
von Kienlin, GCN Circ. 24596
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 ) triggered the CALET Gamma-ray Burst Monitor
(CGBM) at 07:24:59.459 UTC on 19 May 2019.
The burst signal was seen by all CGBM detectors.

The burst light curve shows a broad multi-peaked pulse which starts
at T-4.0 sec and ends at ~T+24 sec, followed by a bright double-peaked
pulse, which starts at T+31.8 sec, peaks at 40.1 sec and ends
at T+45.3 sec. The T90 and T50 durations measured by the SGM data are
42.8 +- 2.5 sec and 24.6 +- 3.5 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1242285834/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.

A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB),
D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), P.A.
Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester) and T.N. Ukwatta report on behalf of the Swift-XRT team:

We have analysed 7.0 ks of XRT data for GRB 190519A (Ukwatta et al. GCN
Circ. 24595
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 ), from 91 s to 46.8 ks after the  BAT trigger. The data
comprise 100 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Beardmore et al. (GCN Circ. 24597
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 ).

The late-time light curve (from T0+13.7 ks) can be modelled with a
power-law decay with a decay index of alpha=1.33 (+/-0.28).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 2.34 (+0.20, -0.18). The
best-fitting absorption column is  6.5 (+1.2, -1.1) x 10^21 cm^-2, in
excess of the Galactic value of 4.3 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.79 (+0.13, -0.12)
and a best-fitting absorption column of 6.8 (+1.1, -1.0) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.9 x 10^-11 (7.5 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     6.8 (+1.1, -1.0) x 10^21 cm^-2
Galactic foreground: 4.3 x 10^21 cm^-2
Excess significance: 4.3 sigma
Photon index:	     1.79 (+0.13, -0.12)

If the light curve continues to decay with a power-law decay index of
1.33, the count rate at T+24 hours will be 0.020 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x
10^-12 (1.5 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00904394.

This circular is an official product of the Swift-XRT team.

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry
downlink,
we report further analysis of BAT GRB 190519A (trigger #904394)
(Ukwatta et al., GCN Circ. 24595
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 ).  The BAT ground-calculated position is
RA, Dec = 114.758, -38.813 deg which is
   RA(J2000)  =  07h 39m 01.9s
   Dec(J2000) = -38d 48' 46.6"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 8%.

The mask-weighted light curve shows a multi-peaked structure that starts at
~T-60 s and ends at ~T+15 s. The main peak occurs at ~T0. T90 (15-350 keV)
is 45.58 +- 2.86 sec (estimated error including systematics).

The time-averaged spectrum from T-56.97 to T+14.79 sec is best fit by a
power law
with an exponential cutoff.  This fit gives a photon index 1.32 +- 0.24,
and Epeak of 90.0 +- 35.0 keV (chi squared 76.36 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.8 +- 0.1 x 10^-5 erg/cm2
and the 1-sec peak flux measured from T-0.21 sec in the 15-150 keV band is
20.6 +- 1.7 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.72 +- 0.06 (chi squared 85.04 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/904394/BA/

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1496 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 190519A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 114.76757, -38.80540 which is equivalent
to:

RA (J2000): 07h 39m 4.22s
Dec (J2000): -38d 48' 19.4"

with an uncertainty of 1.6 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.

A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team:

"At 07:24:57.34 UT on 19 May 2019, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GGRB 190519A (trigger 579943502 / 190519309), which
was also detected by the Swift/BAT (Ukwatta et al. 2019, GCN 24595
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 ). The 
GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 86.4 degrees.

The GBM light curve shows a multi-peaked structure with a duration (T90) 
of about 46 s (50-300 keV). The time-averaged spectrum from T0-3.072 s to T0+50.177 s is
best fit by a power law function with an exponential high-energy cutoff.  
The power law index is -1.06 +/- 0.02 and the cutoff energy, 
parameterized as Epeak, is 112 +/- 3 keV

The event fluence (10-1000 keV) in this time interval is
(3.16 +/- 0.04)E-05 erg/cm^2. The 1.024 sec peak photon flux measured
starting from T0+41.9847 s in the 10-1000 keV band is 35.8 +/- 0.6 ph/s/cm^2.

A Band function fits the spectrum equally well with Epeak= 108 +/- 3 keV, 
alpha = -1.04 +/- 0.03 and beta = -3.1 +/- 0.3.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"

T. N. Ukwatta (LANL), E. Ambrosi (INAF-IASFPA), V. D'Elia (SSDC),
C. Gronwall (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC) and
K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 07:25:39 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 190519A (trigger=904394).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 114.764, -38.824 which is 
   RA(J2000) = 07h 39m 03s
   Dec(J2000) = -38d 49' 26"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 20 sec. In addition, there might be
a weaker pulse that starts at ~ T-50 s. The peak count rate
was ~5500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 07:27:04.3 UT, 85.0 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 114.7673,
-38.8052 which is equivalent to:
   RA(J2000)  = 07h 39m 04.14s
   Dec(J2000) = -38d 48' 18.7"
with an uncertainty of 2.0 arcseconds (radius, 90% containment). This
location is 68 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (4.31 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 3.6
(+2.17/-1.96) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 4.35e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
150 seconds after the BAT trigger. No credible afterglow candidate has been
found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the
XRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. 
Results from the list of sources generated on-board are not available at this
time. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.42. 

Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta AT gmail.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)

The Fermi GBM team reports the detection of a likely LONG GRB

At 07:24:57 UT on 19 May 2019, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 190519A (trigger 579943502.3431 / 190519309).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 114.9, Dec = -35.5 (J2000 degrees, equivalent to J2000 07h 39m, -35d 30'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 85.0 degrees.

The skymap can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190519309/quicklook/glg_skymap_all_bn190519309.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190519309/quicklook/glg_healpix_all_bn190519309.fit

The GBM light curve can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190519309/quicklook/glg_lc_medres34_bn190519309.gif