- Outage caused by a Hurricane near Guam, so no Bacodine transmitted.
- GCN Circular #19761
F. E. Marshall (NASA/GSFC), P. D'Avanzo (INAF-OAB),
J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB) and
M. H. Siegel (PSU) report on behalf of the Swift Team:
At 01:32:47 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 160804A (trigger= 707231 ). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 221.639, +10.001 which is
RA(J2000) = 14h 46m 33.4s
Dec(J2000) = +10d 00m 03.6s
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty).
The XRT began observing the field at 01:35:14 UT, 147 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 221.62909, +9.99599 which
is equivalent to:
RA(J2000) = 14h 46m 31.0s
Dec(J2000) = +09d 59m 45.6s
with an uncertainty of 5 arcseconds (radius, 90% containment). This
location is 39 arcseconds from the BAT onboard position, within the BAT
error circle.
Due to bad weather near Guam, we only have limited information about
this burst at this time. More information will be available after a
full ground station pass.
Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.nasa.gov).
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/too.html.)
- GCN Circular #19762
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 2427 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 160804A, 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 = 221.62988, +9.99889 which is equivalent
to:
RA (J2000): 14h 46m 31.17s
Dec (J2000): +09d 59' 56.0"
with an uncertainty of 1.7 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.
- GCN Circular #19763
P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), T.G.R. Roegiers (PSU), L.M.
McCauley (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A.
Evans (U. Leicester), S.L. Gibson (U. Leicester), A. D'Ai (INAF-IASFPA)
and F.E. Marshall report on behalf of the Swift-XRT team:
We have analysed 6.1 ks of XRT data for GRB 160804A (Marshall et al.
GCN Circ. 19761), from 137 s to 18.0 ks after the BAT trigger. The
data comprise 600 s in Windowed Timing (WT) mode (the first 9 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. 19762).
The late-time light curve (from T0+4.3 ks) can be modelled with a
power-law decay with a decay index of alpha=0.32 (+0.20, -0.19).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.772 (+/-0.023). The
best-fitting absorption column is 1.44 (+/-0.08) x 10^21 cm^-2, in
excess of the Galactic value of 1.9 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.90 (+0.17, -0.16)
and a best-fitting absorption column of 7.1 (+4.3, -3.8) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.4 x 10^-11 (4.0 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 7.1 (+4.3, -3.8) x 10^20 cm^-2
Galactic foreground: 1.9 x 10^20 cm^-2
Excess significance: 2.2 sigma
Photon index: 1.90 (+0.17, -0.16)
If the light curve continues to decay with a power-law decay index of
0.32, the count rate at T+24 hours will be 0.049 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x
10^-12 (1.9 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/00707231.
This circular is an official product of the Swift-XRT team.
- GCN Circular #19764
A. A. Breeveld (UCL-MSSL) and F. E. Marshall (NASA/GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160804A 82=20
s after the BAT trigger (Marshall et al., GCN Circ. 19761).
A fading source consistent with the XRT position (Osborne et al. GCN=20
Circ. 19762) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) =3D 14:46:31.14 =3D 221.62976 (deg.)
Dec (J2000) =3D +09:59:56.7 =3D 9.99908 (deg.)
with an estimated uncertainty of 0.44 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT=20
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for=20
the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 82 232 147 18.56 =B1 0.06
white 794 944 148 19.66 =B1 0.12
v 570 6762 373 >19.9
b 496 6227 432 20.4 =B1 0.24
u 240 490 246 19.53 =B1 0.20
w1 4182 4382 197 18.90 =B1 0.25
m2 1000 5612 216 >18.7
w2 546 6637 432 >19.5
The magnitudes in the table are not corrected for the Galactic=20
extinction due to the reddening of E(B-V) =3D 0.03 in the direction of the
burst (Schlegel et al. 1998).
- GCN Circular #19765
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
F. E. Marshall (NASA/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 recent telemetry downlinks,
we report further analysis of BAT GRB 160804A (trigger #707231)
(Marshall, et al., GCN Circ. 19761). The BAT ground-calculated position is
RA, Dec = 221.652, 10.002 deg, which is
RA(J2000) = 14h 46m 36.4s
Dec(J2000) = +10d 00' 06.2"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 28%.
The mask-weighted light curve shost several overlapping peaks starting
at ~T+20sec (possibly at ~T-30 sec), peaking at ~T+90 sec, and returning
to baseline at ~T+330 sec. T90 (15-350 keV) is 144.2 +- 19.2 sec
(estimated error including systematics).
The time-averaged spectrum from T+25.14 to T+247.15 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.40 +- 0.23,
and Epeak of 52.7 +- 5.4 keV (chi squared 57.0 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 1.14 +- 0.03 x 10^-5 erg/cm2
and the 1-sec peak flux measured from T+88.59 sec in the 15-150 keV band is
2.9 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.99 +- 0.05 (chi squared 79.05 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/707231/BA/
- GCN Circular #19768
N.Tyurina, V. Lipunov, E. Gorbovskoy, V.Kornilov,
P.Balanutsa, A.Kuznetsov, D.Kuvshinov,
Lomonosov Moscow State University, Sternberg Astronomical Institute
D.Buckley, S. Potter, A.Kniazev
South African Astronomical Observatory
N.M.Budnev, O.Gres, K.Ivanov, S.Yazev, V.A.Poleshchuk
Irkutsk State University
A. Tlatov, V.Senik, D. Dormidontov, A.V. Parhomenko
Kislovodsk Solar Station of the Pulkovo Observatory
V.Yurkov, Yu.Sergienko, A.Gabovich
Blagoveschensk Educational State University, Blagoveschensk
H.Levato , C.Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
F. Podest, C. Mallamaci, C. Lopez , R.Podesta
Observatorio Astronomico Felix Aguilar (OAFA)
R. Rebolo, M. Serra Ricart, N. Lodieu, G. Israelian
The Instituto de Astrofisica de Canarias
MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in SAAO was pointed to the GRB160804A (Swift trigger= 707231
came only from (Marshall et al., GCN19761)
at 2016-08-04 17:59:48 UT (16h27m01s after the trigger time). We have set
of images with unfiltered
m_lim=20.7 (540s exposure).
We see the Swift/UVOT source (Breeveld et al., GCN 19764) at Ra Dec
(2000)=14:46:31.14 +09:59:56.7 with unfiltered m_OT~ 20.3.
There is a Sloan galaxy in 0.182" with green g=21.7, red r=21.2m, i.e.
possible host galaxy for this GRB.
- GCN Circular #19769
E. Bissaldi (Politecnico & INFN Bari), C. M. Hui (MSFC),
V. Connaughton (USRA), and Rachel Hamburg (UAH)
report on behalf of the Fermi GBM Team:
"At 01:34:16.04 UT on 04 August 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 160804A (trigger 491967260 / 160804065),
which was also detected by the Swift-BAT (Marshall et al. 2016, GCN 19761).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 87
degrees.
The GBM light curve consists of single emission episode
with a duration (T90) of about 130 s (50-300 keV).
The time-averaged spectrum from T0-60 s to T0+70 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.1 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 74 +/- 3 keV.
The event fluence (10-1000 keV) in this time interval is
(1.5 +/- 0.3)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+10 s in the 10-1000 keV band
is 4.6 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
- GCN Circular #19770
D. Malesani (DARK/NBI and DTU Space), P. D'Avanzo (INAF/OABr), A.
Melandri (INAF/OABr), V. D'Elia (INAF/Roma and ASI/ASDC), and M. Pedani
(INAF/TNG), report on behalf of the CIBO collaboration:
We observed the field of GRB 160804A (Marshall et al., GCN 19761) with
the Telescopio Nazionale Galileo (TNG) equipped with DOLoRes.
Observations were carried out in the r and z filters.
At the position of the optical afterglow (Breeveld & Marshall, GCN
19764), we clearly detect an extended object in both filters.
Calibrating compared to nearby SDSS stars, we measure AB magnitudes r =
20.99 +- 0.04 and z = 19.99 +- 0.17. The mid time of the observations is
Aug 4.89 UT, that is 0.83 days after the trigger.
We note that this object is clearly visible in the SDSS frames, with
catalog magnitudes of r = 21.22 +- 0.11 and z = 20.74 +- 0.35. It is
classified as a galaxy with a (fairly uncertain) photometric redshift z
<~ 0.5 This object is most likely the host galaxy of GRB 160804A.
Our measurements are marginally (2 sigma) brighter than the SDSS values,
though we caution that aperture effects on a low S/N extended object may
be responsible for the difference. In any case, the afterglow is only
contributing little flux at the epoch of the TNG observations.
- GCN Circular #19771
A. S. Moskvitin, T. A. Fatkhullin (SAO RAS, Russia) and I. Soloviev
(Saint-Petersburg Univ.), report on behalf of the larger team.
We observed the field of the GRB 160804A (Marshall et al., GCN 19761)
with the BTA, 6-meter telescope of SAO RAS, equipped with the
Scorpio-I at 2016.08.04 17:52 UT (16.3 hours after the detection).
A couple of Rc-band images (30 and 180 sec.) were obtained.
The GRB OT (Breeveld & Marshall, GCN 19764; Tyurina et al., GCN 19768)
is clearly detected in the stacked frame. The brightness of the object
is R = 20.5 +/- 0.1 (calibration was done by the nearby SDSS stars,
and Lupton 2005 transformation equations).
The finding chart can be found at
ftp://ftp.sao.ru/pub/grb/GRB160804A/GRB180804A_BTA.jpg
- GCN Circular #19773
D. Xu (NAOC), K. E. Heintz (DARK/NBI), D. Malesani (DARK/NBI and DTU
Space), K. Wiersema (U. Leicester), J. P. U. Fynbo (DARK/NBI), report on
behalf of a larger collaboration:
We observed the optical afterglow of GRB 160804A (Marshall et al., GCN
19761; Breeveld et al., GCN 19764) with the ESO VLT UT2 (Kueyen)
equipped with the X-shooter spectrograph. Observations started at 23:55
UT on 2016-08-04 (22.37 hr after the BAT trigger) and consisted of 4
spectra by 600 s each, covering the wavelength range 3500-20000 AA.
The continuum trace is well detected in our exposures, down to ~3100 AA.
The lack of any drop sets an upper limit to the redshift z < 1.55. A
number of superimposed absorption features are detected, which we
interpret as due to Mg I, Mg II, Fe II, Al II, as well as emission
features due to [O II], [O III], Halpha, Hbeta, Hgamma, [N II], [S II],
[S III], all at a common redshift z = 0.736. We thus conclude this is
the redshift of GRB 160804A.
We acknowledge excellent support from the ESO observing staff in
Paranal, in particular Jonathan Smoker, Leo Rivas, and Stephane Brillant.
- GCN Circular #19774
J. Bolmer and J. Greiner (both MPE Garching) report on behalf
of the GROND team:
We observed the field of GRB 160804A (Swift trigger 707231; Marshall et
al., GCN #19761) simultaneously in g'r'i'z'JHK with GROND (Greiner
et al. 2008, PASP 120, 405) mounted at the 2.2m MPG telescope at the
ESO La Silla Observatory (Chile).
Observations started at 23:12:02 UT on 2016-08-04, 21.7 hr after the GRB
trigger. They were performed at an average seeing of 1.3", at an
average airmass of 1.5.
We clearly detect the source reported by Breeveld et al. (GCN #19764),
Tyurina et al.
(GCN #19768), Malesani et al. (GCN #19770), Moskvitin et al. (GCN #19771)
and Xu et al. (GCN #19773).
Based on images with 84 min of total exposure in g'r'i'z'
and 80 min in JHK at a mid-time of 00:15:10 UT on 2016-08-05,
we derive the following preliminary magnitudes (all in AB system):
g' = 21.50 +- 0.03 mag
r' = 21.21 +- 0.03 mag
i' = 20.85 +- 0.03 mag
z' = 20.66 +- 0.03 mag
J = 20.20 +- 0.07 mag
H = 19.88 +- 0.07 mag
K = 19.69 +- 0.12 mag
Given magnitudes are calibrated against SDSS as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V) =3D 0.02 mag in the
direction of the burst (Schlafly & Finkbeiner 2011).
We note that our r'- and z'-band magnitudes are consistent with
the SDSS catalog magnitudes of the host galaxy (as reported by Malesani et
al., GCN #19770).
- GCN Circular #19775
E. Mazaeva (IKI), E. Chornaya (UAFO, ISON), A. Matkin (UAFO), I.
Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB
follow-up collaboration:
We observed the field of GRB 160804A (Marshall et al., GCN 19761) with
SANTEL-650 (0.65m) telescope of UAFO/ISON-Ussuriysk observatory. We
obtained several unfiltered images starting on August 04 (UT)
12:03:56. We clearly detected optical source reported by Breeveld et
al. (GCN 19764), Tyurina et al. (GCN 19768), Malesani et al. (GCN
19770), Moskvitin et al. (GCN 19771), Xu et al. (GCN #19773) and Bolmer
et al. (GCN 19774). Preliminary photometry of a combined image is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2016-08-04 12:03:56 0.46189 CR 60*120 19.90 0.27 21.6
Photometry is based on nearby SDSS DR9 stars
SDSS-DR9_id R(Lupton)
J144642.43+100147.7 18.068
J144642.15+100017.4 17.644
J144638.04+095917.6 17.971
J144635.67+095910.6 18.378
J144619.22+095958.1 16.677
J144616.60+100018.4 16.575
J144614.88+100001.4 16.544
- GCN Circular #19776
E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), I. Reva
(Fesenkov Astrophysical Institute), A. Volnova (IKI), A. Pozanenko (IKI)
report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 160804A (Marshall et al., GCN 19761) with
Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory.
We obtained several images in R filter starting on August 04 (UT)
15:08:18. We clearly detected optical source reported by Breeveld et
al. (GCN 19764), Tyurina et al. (GCN 19768), Malesani et al. (GCN
19770), Moskvitin et al. (GCN 19771), Xu et al. (GCN #19773) and Bolmer
et al. (GCN 19774). Preliminary photometry of a combined image is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2016-08-04 15:08:18 0.58601 R 26*120 20.30 0.10 21.4
Photometry is based on nearby SDSS DR9 stars
SDSS-DR9_id R(Lupton)
J144642.43+100147.7 18.068
J144642.15+100017.4 17.644
J144638.04+095917.6 17.971
J144635.67+095910.6 18.378
J144632.91+100104.9 17.910
J144619.22+095958.1 16.677
J144616.60+100018.4 16.575
J144614.88+100001.4 16.544
- GCN Circular #19779
Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J.
Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara
(GSFC/STScI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels=
(GSFC),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and
Vicki Toy (UMD) report:
We observed the field of GRB 160804A (Marshall et al., GCN Circular
19761) with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
Astron=F3mico Nacional on Sierra San Pedro M=E1rtir from 2016/08 5.16 to
2016/08 5.27 UTC (26.33 to 29.04 hours after the BAT trigger), obtaining
a total of 1.78 hours exposure in the r and i bands and 0.75 hours
exposure in the Z, Y, J, and H bands.
We detect a source coincident with Swift/UVOT source (Breeveld et al.,
GCN Circular 19764) with the following magnitudes and 3-sigma upper
limit:
r = 21.29 +/- 0.02
i = 20.90 +/- 0.02
Z = 21.12 +/- 0.19
Y = 21.04 +/- 0.29
J = 20.52 +/- 0.23
H > 20.51
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro
M=E1rtir.
- GCN Circular #19813
K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson
(Curtin), T. Cantwell (Manchester), C. Rumsey, D. Titterington, S. H.
Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge),
K. Grainge, A. Scaife (Manchester)
The AMI Large Array triggered on the Swift alert for GRB 160804A
(Marshall et al., GCN 19761) as part of the 4pisky program, and
subsequent follow up observations were obtained up to 12 days
post-burst. Our observations at 15 GHz on 2016 Aug 04.85, Aug 05.75, Aug
07.75, Aug 11.75, and Aug 16.67 (UT) reveal a transient radio source at
the XRT location (Osborne et al., GCN 19762), with flux densities of
<141 uJy (3sigma), 189+/-46 uJy, 583+/-40 uJy, 292+/-34 uJy, and
168+/-38 uJy respectively.
We thank the AMI staff for scheduling these observations. The AMI-GRB
database is a log of all GRB follow up observations with the AMI, and is
available at http://4pisky.org/ami-grb/.
Previous IAU Circulars 
