GRB 190719C
GCN Circular 25252
Subject
GRB 190719C: VLT/X-shooter spectroscopic redshift of the host galaxy
Date
2019-08-01T22:01:30Z (6 years ago)
From
Andrea Rossi at INAF <andrea.rossi@inaf.it>
A. Rossi (INAF-OAS), K. E. Heintz (Univ. Iceland), J. P. U. Fynbo
(DAWN/NBI), D. B. Malesani (DTU Space), A. de Ugarte Postigo
(HETH/IAA-CSIC, DARK/NBI), S. D. Vergani (Obs. Paris/GEPI and CNRS), D.
A. Kann, C. C. Thoene, L. Izzo (HETH/IAA-CSIC), S. Campana (INAF-OAB),
G. Pugliese, L. Kaper (Univ. Amsterdam), C. Kouveliotou (GWU), and N. R.
Tanvir (Univ. Leicester) report on behalf of the Stargate collaboration:
We observed the location of the candidate host galaxy (Malesani et al.,
GCN 25110; Heintz et al., GCN 25144) of GRB 190719C (Ambrosi et al., GCN
25106; Poolakkil & Meegan, GCN 25130) using the ESO VLT UT2 (Kueyen)
equipped with the X-shooter spectrograph. Our spectra cover the
wavelength range 3000-21000 AA, and consist of 4 exposures by 600 s
each. Our observations started on 2019 August 01 at 00:48:20 UT, ~13.4
days after the GRB detection. The slit was centred on the nucleus of the
nearby object visible in the Pan-STARRS archival images, and was
oriented in order to include the afterglow position.
While only weak continuum is visible, several clear emission lines are
detected in the near-infrared arm. We identify the [O ii] 3727/3729
doublet, Hbeta, [O iii] 4959, and [O iii] 5007, at a common redshift z =
2.469.
No clear emission (lines nor continuum) is detected at the location of
the afterglow, so we have no direct measurement of the GRB redshift. The
random association probability with the Pan-STARRS object is however
rather small (~3*10^-3), suggesting a physical connection. We also note
that the Pan-STARRS galaxy is exceptionally luminous, with an absolute
magnitude M = -22.9 AB (computed at 1800 AA rest frame). The measured
offset would correspond to 6.6 kpc in projection - a rather large value
but not surprising for such a bright host. In conclusion, we propose z =
2.469 as the redshift of GRB 190719C.
We acknowledge excellent support from the ESO observing staff in
Paranal, in particular Gaspare Lo Curto, Marcela Espinoza, Boris
Haeussler, Aleksandra Solarz, and Steffen Mieske.
GCN Circular 25144
Subject
GRB 190719C: optical afterglow confirmation
Date
2019-07-24T08:31:42Z (6 years ago)
From
Kasper Elm Heintz at Univ. of Iceland and DAWN/NBI <keh14@hi.is>
Kasper E. Heintz (Univ. Iceland), Daniele B. Malesani (DTU Space), Daniel A. Perley (LJMU), Shane Moran (NOT and Univ. Turku), report on behalf of a larger collaboration:
We observed again the field of GRB 190719C (Ambrosi et al., GCN 25106; Poolakkil & Meegan, GCN 25130) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. A coadded exposure of 3000 s was collected in the SDSS r filter, starting on July 21.125 UT (1.501 days after the GRB).
The source first noticed in our previous observation (Malesani et al., GCN 25110) visually faded and is no longer clearly detected. This was quantitatively confirmed by carrying out image subtraction between the two epochs. A clear residual is visible at coordinates (J2000):
RA = 16:00:49.58
Dec = 13:00:04.5
This is approximately 0.7" west of the object visible in the archival Pan-STARRS images.
Photometry of the transient computed on the subtraction image (calibrated against nearby stars from the Pan-STARRS catalog) yields r = 23.03 +- 0.12 AB at epoch July 19.88 UT (Malesani et al., GCN 25110). We caution that the actual brightness would be higher if significant residual light were present in our second epoch of observation (this would be ~20% for a t^-1 decay).
The consistency with the X-ray afterglow position (Beardmore et al., GCN 25125) and the optical fading confirm that the source above is the afterglow of GRB 190719C. The close angular proximity with the object seen in the Pan-STARRS images suggests it to be the GRB host galaxy.
GCN Circular 25130
Subject
GRB 190719C: Fermi GBM detection
Date
2019-07-20T20:29:46Z (6 years ago)
From
Suraj Poolakkil at UAH <sp0076@uah.edu>
S. Poolakkil (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
At 14:58:34.56 UT on 19 July 2019, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 190719C (trigger 585241119/ 190719624),
which was also detected by the Swift/BAT (Ambrosi et al. 2019, GCN 25106).
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 degrees.
The GBM lightcurve shows an initial bright short spike followed
by longer duration emission containing multiple peaks.
with a duration (T90) of about 175 s (50-300 keV).
The time-averaged spectrum from T0-2.0 s to T0+3.0 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.87 +/- 0.18 and
the cutoff energy, parameterized as Epeak, is 81 +/- 9 keV.
The event fluence (10-1000 keV) in this time interval is
(1.155 +/- 0.082)E-06 erg/cm^2. The 1-sec peak photon flux
measured starting from T+0.19 s in the 10-1000 keV band
is 8.3 +/- 0.3 ph/s/cm^2.
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/"
GCN Circular 25129
Subject
GRB 190719C: Swift-BAT refined analysis
Date
2019-07-20T17:47:52Z (6 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
T. Sakamoto (AGU), E. Ambrosi (INAF-IASFPA),
S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry
downlink,
we report further analysis of BAT GRB 190719C (trigger #915381)
(Ambrosi et al., GCN Circ. 25106). The BAT ground-calculated position is
RA, Dec = 240.208, 13.005 deg which is
RA(J2000) = 16h 00m 49.8s
Dec(J2000) = +13d 00' 18.4"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The mask-weighted light curve shows a multi-peaked structure that starts
at ~T0 and ends at ~T+200 s. The main peak occurs at ~T0. T90 (15-350 keV)
is 185.7 +- 9.7 sec (estimated error including systematics).
The time-averaged spectrum from T-0.09 to T+201.96 sec is best fit by a
simple
power-law model. The power law index of the time-averaged spectrum is
1.64 +- 0.09. The fluence in the 15-150 keV band is 5.1 +- 0.3 x 10^-6
erg/cm2.
The 1-sec peak photon flux measured from T+0.27 sec in the 15-150 keV band
is 5.5 +- 0.3 ph/cm2/sec. 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/915381/BA/
GCN Circular 25128
Subject
GRB 190719C: Swift/UVOT Upper Limits
Date
2019-07-20T16:32:27Z (6 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and E. Ambrosi (INAF-IASFPA)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 190719C
71 s after the BAT trigger (Ambrosi et al., GCN Circ. 25106).
No optical afterglow consistent with the XRT position 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
white_FC 71 221 147 >20.6
u_FC 283 533 246 >20.6
white 71 756 186 >20.8
v 613 807 39 >18.7
b 538 732 39 >19.9
u 283 706 265 >20.5
w1 662 856 39 >19.2
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).
The upper limits are consistent with the faint candidate
afterglow reported by Malesani et al. (GCN Circ. 25110).
GCN Circular 25126
Subject
GRB 190719C: Swift-XRT light-curve fit
Date
2019-07-20T15:41:49Z (6 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:
GCN Circ. 25125 was missing the details of the fit to the XRT light-curve.
The correct information is as follows:
The light curve can be modelled with an initial power-law decay with an
index of alpha=2.11 (+/-0.05), followed by a break at T+387 s to an
alpha of 3.7 (+1.0, -0.4). A second break occurs at T+967 s to an alpha of
0.33 (+0.06, -0.09).
If the light curve continues to decay with a power-law decay index of
0.33, the count rate at T+24 hours will be 0.14 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.3 x
10^-12 (7.0 x 10^-12) erg cm^-2 s^-1.
We apologise for the omission of these numbers in the earlier circular.
This circular is an official product of the Swift-XRT team.
GCN Circular 25125
Subject
GRB 190719C: Swift-XRT refined Analysis
Date
2019-07-20T15:22:02Z (6 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne
(U. Leicester), M.G. Bernardini (INAF-OAB), M. Capalbi (INAF-IASFPA),
D.N. Burrows (PSU), J. D. Gropp (PSU), A. Tohuvavohu (PSU) and E.
Ambrosi report on behalf of the Swift-XRT team:
We have analysed 2.4 ks of XRT data for GRB 190719C (Ambrosi et al. GCN
Circ. 25106), from 64 s to 52.0 ks after the BAT trigger. The data
comprise 353 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The refined XRT position is RA, Dec =
240.2069, +13.0000 which is equivalent to:
RA (J2000): 16 00 49.65
Dec(J2000): +13 00 00.0
with an uncertainty of 3.6 arcsec (radius, 90% confidence). a rise,
withpower-law index .
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.42 (+0.04, -0.03). The
best-fitting absorption column is 2.26 (+0.19, -0.18) x 10^21 cm^-2,
in excess of the Galactic value of 4.7 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.54 (+0.29, -0.25)
and a best-fitting absorption column of 9.0 (+9.8, -4.3) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 4.5 x 10^-11 (5.0 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 9.0 (+9.8, -4.3) x 10^20 cm^-2
Galactic foreground: 4.7 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.54 (+0.29, -0.25)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00915381.
This circular is an official product of the Swift-XRT team.
GCN Circular 25110
Subject
GRB 190719C: NOT candidate optical afterglow and host
Date
2019-07-19T23:23:34Z (6 years ago)
From
Kasper Elm Heintz at Univ. of Iceland and DAWN/NBI <keh14@hi.is>
Daniele B. Malesani (DTU Space), Kasper E. Heintz (Univ. Iceland), Daniel A. Perley (LJMU), Bo Milvang-Jensen (DAWN/NBI), Shane Moran (NOT and Univ. Turku) report on behalf of a larger collaboration:
We observed the field of the Fermi and Swift GRB 190719C (Fermi GBM Team, GCN 25104; Ambrosi et al., GCN 25106) using the Nordic Optical Telescope equipped with the ALFOSC camera. A set of 3 exposures by 300 s each was secured in the r band.
At the edge of the currently available XRT error circle (3.6" error radius), a single object is detected at approximate coordinates (J2000):
RA = 16:00:49.59
Dec = +13:00:04.3
This object is clearly extended, and we measure r = 22.01 +- 0.05 AB using a wide aperture, calibrated against nearby Pan-STARRS objects.
We notice that the object is also detected in the Pan-STARRS r-band image, for which we measure a slightly fainter magnitude r = 22.50 +- 0.16 AB. Visual comparison of the NOT and Pan-STARRS images indicated a shift in the centroid between the two epochs, with excess light in the NOT images to the West of the archival object.
We thus suggest that we are seeing a faint afterglow superimposed on its host galaxy. Further imaging at later epochs is required to carry out image subtraction and provide accurate position and magnitude for the afterglow.
New observations with the NOT will be requested as soon as the telescope is available.
GCN Circular 25106
Subject
GRB 190719C: Swift detection of a burst
Date
2019-07-19T15:22:37Z (6 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
E. Ambrosi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC),
J.D. Gropp (PSU), N. J. Klingler (PSU), H. A. Krimm (NSF),
N. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), B. Sbarufatti (PSU) and A. Tohuvavohu (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:
At 14:58:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 190719C (trigger=915381). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 240.210, +12.977 which is
RA(J2000) = 16h 00m 50s
Dec(J2000) = +12d 58' 39"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a multi-peaked
structure with a total duration of about 100 sec. The peak count rate
was ~6000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 14:59:35.3 UT, 60.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 240.20700,
12.99995 which is equivalent to:
RA(J2000) = 16h 00m 49.68s
Dec(J2000) = +12d 59' 59.8"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 83 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 (4.69 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.9
(+3.40/-2.88) x 10^21 cm^-2 (90% confidence).
The initial flux in the 0.1 s image was 1.69e-08 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 71 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 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.04.
The Fermi GBM team announced the detection of GRB 190719C (GCN Circ
25104). Given the temporal coincidence, it is likely that this is the
same burst.
Burst Advocate for this burst is E. Ambrosi (elena.ambrosi AT inaf.it).
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/)
GCN Circular 25104
Subject
GRB 190719C: Fermi GBM Final Real-time Localization
Date
2019-07-19T15:09:44Z (6 years ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
The Fermi GBM team reports the detection of a likely SHORT GRB
At 14:58:34 UT on 19 Jul 2019, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 190719C (trigger 585241119.558452 / 190719624).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 244.5, Dec = 4.9 (J2000 degrees, equivalent to J2000 16h 18m, 4d 54'), with a statistical uncertainty of 4.6 degrees.
The angle from the Fermi LAT boresight is 92.0 degrees.
The skymap can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190719624/quicklook/glg_skymap_all_bn190719624.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/bn190719624/quicklook/glg_healpix_all_bn190719624.fit
The GBM light curve can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190719624/quicklook/glg_lc_medres34_bn190719624.gif