GRB 080413B
GCN Circular 7598
Subject
GRB 080413B: Swift detection of a possibly short burst with optical counterpart
Date
2008-04-13T09:20:28Z (17 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
M. Stamatikos (NASA/ORAU), A. P. Beardmore (U Leicester),
N. Gehrels (NASA/GSFC), S. D. Hunsberger (PSU),
C. B. Markwardt (CRESST/GSFC/UMD), J. P. Osborne (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
T. Sakamoto (NASA/UMBC), R. L. C. Starling (U Leicester) and
E. Troja (U Leicester/INAF-IASFPA) report on behalf of the Swift
Team:
At 08:51:12 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080413B (trigger=309111). Swift started slewing approximately
70 seconds after the burst. The BAT on-board calculated location is
RA, Dec 326.134, -19.969 which is
RA(J2000) = 21h 44m 32s
Dec(J2000) = -19d 58' 08"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single peaked
structure with a duration of about 3 sec. The peak count rate
was ~15,000 counts/sec (15-350 keV), at ~0.2 sec after the trigger.
The XRT began observing the field at 08:53:23.8 UT, 131.2 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 326.14434,
-19.98104 which is equivalent to:
RA(J2000) = 21h 44m 34.64s
Dec(J2000) = -19d 58' 51.7"
with an uncertainty of 2.6 arcseconds (radius, 90% containment). This
location is 55 arcseconds from the BAT onboard position, within the BAT
error circle.
A power-law fit to a spectrum formed from promptly downlinked event
data does not constrain the column density, so we cannot provide limits
on the redshift using spectroscopy and the relation from Grupe et al.
(2007). A summary of the promptly downlinked data is given at
http://www.swift.ac.uk/sper/309111/.
UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 134 seconds after the BAT trigger. There is a candidate
afterglow in the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 21:44:34.68 = 326.1445
DEC(J2000) = -19:58:52.0 = -19.9811
with a 1-sigma error radius of about 0.6 arc sec. This position is 0.6 arc
sec. from the XRT position. The estimated magnitude is 16.5
with a 1-sigma error of about 0.5 mag. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.04.
Burst Advocate for this burst is M. Stamatikos (michael 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 7599
Subject
GRB 080413B: GROND detection of afterglow in all bands
Date
2008-04-13T09:32:15Z (17 years ago)
From
Jochen Greiner at MPI <jcg@mpe.mpg.de>
T. Kruehler, J. Greiner, A. Kupcu Yoldas, C. Clemens, A. Yoldas (all MPE
Garching) and G. Szokoly (Eoetvoes Univ. Budapest and MPE Garching)
report on behalf of the GROND team:
We observed the field of GRB 080413B detected by Swift/BAT (trigger 309111,
Stamatikos et al. 2008, GCN Circ. 7598) simultaneously in g'r'i'z'JHK
with GROND mounted at the 2.2m ESO/MPI telescope at La Silla Observatory
(Chile). Observations started at 08:56 UT on April 13th, 2008, 5 min after
the burst.
We detect a new bright point source at
RA (J2000.0) = 21:44:34.67
DEC (J2000.0) = -19:58:52.4
with an uncertainty of 0.5", which is consistent with the UVOT
position.
The object is detected in all seven bands, implying a redshift
smaller than 3.5.
Preliminary photometry of the first 4 min exposure yields an J band
magnitude of 16.5 calibrated against 2MASS field stars.
The given magnitude is not corrected for the Galactic foreground
reddening of E(B-V)=0.04 mag (Schlegel et al., 1998).
GCN Circular 7600
Subject
GRB080413B: REM NIR & Optical Observation
Date
2008-04-13T10:06:45Z (17 years ago)
From
Angelo Antonelli at Obs. Astro. di Roma <a.antonelli@oa-roma.inaf.it>
L.A. Antonelli, S. Covino, P. D'Avanzo, D. Fugazza, L. Calzoletti,
S. Campana, G. Chincarini, M.L. Conciatore, S. Cutini, V. D'Elia, F.
D'Alessio, F. Fiore, P. Goldoni, D. Guetta, C. Guidorzi, G.L.
Israel, E. Maiorano, N. Masetti, A. Melandri, E. Meurs, L. Nicastro,
E. Palazzi, E. Pian, S. Piranomonte, L. Stella, G. Stratta, G.
Tagliaferri, G. Tosti, V.Testa, S.D. Vergani, F. Vitali report on
behalf of the REM team:
The robotic 60-cm REM telescope located at La Silla (Chile) observed
automatically the field of the GRB 080413B on April 13 08:52:43 UT
(about 91 seconds after the burst).
The afterglow reported in GCN 7598, 7599 (Stamatikos et al., Kruehler
et al.) is well detected in our early images at about H~14.3.
Further analyses and observations are in progress.
GCN Circular 7601
Subject
GRB 080413B: VLT redshift
Date
2008-04-13T10:58:47Z (17 years ago)
From
Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center <malesani@astro.ku.dk>
Paul M. Vreeswijk, Christina C. Thoene, Daniele Malesani, Johan P. U.
Fynbo, Jens Hjorth (DARK/NBI), Pall Jakobsson (Univ. Hertfordshire),
Nial R. Tanvir (Univ. Leicester), and Andrew J. Levan (Univ. Warwick),
report on behalf of a larger collaboration:
We observed the afterglow of the possibly short GRB 080413B (Stamatikos
et al., GCN 7598) with the ESO VLT equipped with FORS1. A 600 s spectrum
centered on Apr 13.403 UT (49.5 min after the GRB) was acquired covering
the range 3500-9000 AA.
From detection of numerous absorption features, including Fe II, Mg II
and Mg I lines, we infer a redshift z = 1.10. In particular, we detect
the Fe II 2396 fine-structure line, which confirms this redshift is very
likely that of the host of the GRB.
We acknowledge excellent support from the VLT staff, particularly Thomas
Szeifert, Jose Cortes, and Gianni Marconi.
GCN Circular 7606
Subject
GRB 080413B, Swift-BAT refined analysis
Date
2008-04-13T17:27:57Z (17 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), J. Cummings (GSFC/UMBC),
E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. Palmer (LANL),
T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-119 to T+148 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 080413B (trigger #309111)
(Stamatikos, et al., GCN Circ. 7598). The BAT ground-calculated position is
RA, Dec = 326.138, -19.981 deg, which is
RA(J2000) = 21h 44m 33.1s
Dec(J2000) = -19d 58' 49.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 20%.
The mask-weighted light curve shows a single FRED-like peak starting
at T-1.1 sec, peaking at T+0.2 sec, and returning to baseline at ~T+30 sec.
T90 (15-350 keV) is 8.0 +- 1.0 sec (estimated error including systematics).
The time-averaged spectrum from T-1.3 to T+10.7 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.26 +- 0.27,
and Epeak of 73.3 +- 15.8 keV (chi squared 32.60 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 3.2 +- 0.1 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T-0.26 sec in the 15-150 keV band is
18.7 +- 0.8 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.80 +- 0.06 (chi squared 45.07 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/309111/BA/
GCN Circular 7608
Subject
GRB 080413B: Swift XRT refined analysis
Date
2008-04-13T18:55:01Z (17 years ago)
From
Eleonora Troja at INAF-IASFPA <nora@ifc.inaf.it>
E. Troja (U. Leicester/INAF-IASFPa) and M. Stamatikos (NASA/ORAU)
report on behalf of the Swift-XRT team:
We have analysed 9.9 ks of Swift XRT data for GRB 080413B (Stamatikos et
al. GCN Circ. 7598), from T0+134 s to T0+20.1 ks.
The data set consists of 376 s exposure in Windowed Timing (WT) mode
followed by 9.5 ks exposure in Photon Counting (PC) mode.
By using orbits 2-4 of PC data [from T0+6.0 ks to T0+20.1 ks]
in order to avoid pile-up effects, we derive an XRT refined position
RA (2000) = 21h 44m 34.43s = 326.1435 d
Dec (2000) = -19d 58' 52.9" = -19.9814 d
with an uncertainty of 3.7 arcsec (90% containment). This position
is 3.6 arcsec from the UVOT candidate afterglow (GCN Circ. 7598),
and 3.4 arcsec from the source reported in Kruehler et al. (GCN Circ.
7599).
The X-ray light curve is well fitted by a simple power-law, with a
decay slope of 0.88 +/- 0.06.
A spectrum obtained from the WT mode data, from T0+135 s to T0+511 s,
can be modelled with an absorbed power-law with a photon index of
2.05 +/- 0.10 , and a redshifted absorbing column of (0.32 +/- 0.13)
x 10^22 cm^-2 at a redshift of z=1.1 (Vreeswijk et al. GCN Circ 7601)
in addition to the Galactic column of 3.06 x 10^20 cm^-2 (Kalberla et
al. 2005). The observed (unabsorbed) 0.3-10 keV flux in this spectrum is
1.79 x 10^-10 (2.13 x 10^-10) erg/cm^2/s.
The PC spectrum of the first four orbits, from T0+512 s to T0+20.1 ks,
can be fit by an absorbed power-law model with photon index 1.93 +/-
0.08 and a column density consistent with the WT spectrum.
All the reported errors are at the 90% confidence level.
If the source continues to decay at the present rate, we predict a count
rate of 0.035 count/sec at T0+24 hours, which corresponds to a 0.3-10 keV
observed (unabsorbed) flux of 1.6 x 10^-12 (1.8 x 10^-12) erg/cm^2/s.
This circular is an official product of the Swift-XRT team.
GCN Circular 7610
Subject
Swift-BAT spectral lag analysis of GRB 080413B
Date
2008-04-13T19:59:34Z (17 years ago)
From
Michael Stamatikos at GSFC <michael.stamatikos-1@nasa.gov>
T. Sakamoto (GSFC/UMBC), T. Ukwatta (GWU), M. Stamatikos (GSFC/ORAU), S. D.
Barthelmy (GSFC), N. Gehrels (GSFC),
We further report on additional spectral lag analysis regarding the possible
short duration burst classification of GRB 080413B (Stamatikos et al. GCN
Circ. 7598). We now believe GRB 080413B to be a long GRB based upon the
following BAT prompt emission properties:
1) The spectral lag in 25-50 to 100-350 keV bands and 15-25 to 50-100 keV
bands are 0.238 +- 0.016 sec and 0.136 +- 0.008 sec for 4 ms binning.
Therefore, GRB 080413B shows a significant lag.
2) The T90 of the spike is 8.0 +- 1.0 sec based on the mask-weighted light
curve (Barthelmy et al., GCN 7606), which is well within the long duration
GRB population (Sakamoto et al. ApJS, 175, 179).
GCN Circular 7611
Subject
GRB080413B
Date
2008-04-13T20:38:00Z (17 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates and M. Stamatikos report on behalf of the Swift/UVOT team.
The Swift/UVOT began settled observations of the field of GRB 080413B 135s
after the BAT trigger (Stamatikos et al., GCN 7598). We detect the
afterglow
in the 7 UVOT filters at the position:
RA(J2000.0) = 21:44:34.65
DEC(J2000.0) = -19:58:52.40
with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence).
This position is
consistent with the refined XRT position and the GROND optical position
(Kruehler et al., GCN 7599).
The magnitudes are reported below:
Filter T_Mid(s) Expo(s) Magnitude
-------------------------------------------------------
White 184 98 16.67 � 0.02
White 740 10 17.67 � 0.15
v 440 393 17.64 � 0.10
v 1183 393 18.64 � 0.22
b 727 10 18.82 � 0.71
u 796 19 17.67 � 0.27
w1 682 19 17.42 � 0.27
m2 810 19 18.07 � 0.47
w2 762 19 17.92 � 0.36
-------------------------------------------------------
The above magnitudes are not corrected for the Galactic extinction
corresponding to a
reddening of E_{B-V} = 0.04 mag (Schlegel et al., 1998, ApJS, 500, 525).
The photometry
is on the UVOT flight system described in Poole et al.
(2008,MNRAS,383,627).
GCN Circular 7612
Subject
GRB 080413B: Ep,i-Eiso correlation
Date
2008-04-13T22:47:19Z (17 years ago)
From
Lorenzo Amati at INAF-IASF/Bologna <amati@iasfbo.inaf.it>
L. Amati (INAF - IASF Bologna),
By assuming the VLT redshift of 1.10 (Vreeswijk et al., GCN 7601), the
values of spectral parameters alpha and Ep, and the fluence, provided
by Swift/BAT (Barthelmy et al., GCN 7606), a value of spectral parameter
beta of -2.3 and a Lambda-CDM cosmology with H0=70 km/s/Mpc, Omega_M=0.27
and Omega_Lambda=0.73, the values of Ep,i and Eiso (1-10000 keV
cosmological rest-frame) of GRB 080413B are approximately 150+/30 keV and
(2.4+/-0.2)x10^52 erg, fully consistent with the Ep,i-Eiso correlation.
Given that this correlation holds for long GRBs only (see, e.g., Amati,
MNRAS, 2006; Amati, astroph/0611189), this is a further evidence that
GRB 080412B is not a short GRB.
This message may be cited.
GCN Circular 7615
Subject
GRB 080413B: Gemini-South Spectroscopy
Date
2008-04-14T16:42:35Z (17 years ago)
From
Antonino Cucchiara at PSU <cucchiara@astro.psu.edu>
A. Cucchiara and D. B. Fox (Penn State) with S. B. Cenko (Caltech),
report on behalf of a larger collaboration:
"Starting on 2008 April 13.41 UT we observed GRB 080413B (Stamatikos
et al. GCN 7598) with the GMOS spectrograph on the Gemini South
telescope. We obtained a single 900-sec spectrum in the wavelength
range 3900-6700A. The resolution of our spectrum is 5 Ang/pixel (R ~
1100 at 5900A). We clearly observe several metal absorption features
corresponding to the MgII doublet (2796,2803 A), MgI (2853A), FeII
(2586A and 2600A), and FeI (3021A). These identifications are
consistent with a host galaxy redshift of z = 1.10, confirming the
result reported from VLT observations by Vreeswijk et al.(GCN 7601)."
GCN Circular 7617
Subject
VLA radio observations of GRB 080413B
Date
2008-04-14T17:34:10Z (17 years ago)
From
Poonam Chandra at U Virginia/NRAO <pc8s@virginia.edu>
Poonam Chandra (NRAO/UVA) and Dale A. Frail (NRAO) report on behalf
of the Caltech-NRAO-Carnegie GRB Collaboration:
"We used the Very Large Array to observe the field of view toward GRB
080413B (GCN 7598) at a frequency of 8.46 GHz at 2008 April 14.59 UT.
We do not detect the GRB afterglow at the GROUND optical position (GCN
7599). The flux density at the GRB afterglow position is 86 � 36 uJy.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 7623
Subject
GRB 080413B: Suzaku WAM observation of the prompt emission
Date
2008-04-16T15:33:02Z (17 years ago)
From
Kazutaka Yamaoka at Aoyama Gakuin U <yamaoka@phys.aoyama.ac.jp>
T. Enoto (Univ. of Tokyo), Y.E. Nakagawa, T. Tamagawa (RIKEN),
T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima
U.), K. Yamaoka, S. Sugita (Aoyama Gakuin U.), M. Tashiro, Y. Terada,
Y. Urata, A. Endo, K. Onda, N. Kodaka, K. Morigami (Saitama U.),
K. Nakazawa, K. Makishima (Univ. of Tokyo), E. Sonoda, M. Yamauchi,
H. Tanaka, R. Hara (Univ. of Miyazaki), M. Ohno, M. Kokubun,
M. Suzuki, T. Takahashi (ISAS/JAXA), S. Hong (Nihon U.),
on behalf of the Suzaku WAM team, report:
The Swift GRB 080413B (Swift/BAT trigger #309111 ; Stamatikos et al., GCN 7598)
was detected by the Suzaku Wide-band All-sky Monitor (WAM) which
covers an energy range of 50 keV - 5 MeV at 8:51:11.645 UT (=T0).
The observed light curve shows a single peak starting at T0-0s,
with a duration (T90) of about 2 seconds. The fluence in 150 - 1000 keV
was (1.4 +/- 0.3) x 10^-6 erg/cm^2. The 1-s peak flux measured from T0+1s was
3.4 +/- 0.2 photons/cm^2/s in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0-1s to T0+8s
is fitted by a single power-law with a photon index of 3.02 (+0.36, -0.32)
(chi^2/d.o.f = 16.7/16) in 150 - 1000 keV. All the quoted errors are at statistical
90% confidence level, in which the systematic uncertainties are not included.
The light curves with 1-sec time resolution for this burst are now available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html
GCN Circular 7626
Subject
GRB 080413B: Faulkes Telescope South optical afterglow observations
Date
2008-04-16T17:48:34Z (17 years ago)
From
Andreja Gomboc at LT,ARI,Liverpool JMU <ag@astro.livjm.ac.uk>
A. Gomboc (Ljubljana), C. Guidorzi (U. Bicocca/INAF-OAB), A. Melandri,
I.A. Steele, C.G. Mundell, D.F. Bersier, M.F. Bode, M.J. Burgdorf, S.N. Fraser,
S. Kobayashi, C.J. Mottram, R.J. Smith (Liverpool JMU), P. O'Brien, N.
Bannister, N. Tanvir (U. Leicester) report on behalf of larger GRB
collaboration:
The 2-m Faulkes Telescope South observed the field of GRB 080413B
(trigger=309111, Stamatikos et al. GCN 7598) starting 8.7-hr after the
trigger time.
We detect the optical afterglow (Stamatikos et al. GCN 7598, Kruehler et al.
GCN 7599, Antonelli et al. GCN 7600) and measure the following magnitudes:
Filter T_mid(hr) Exposure(s) Mag
----------------------------------------------------------------------
R 8.74 30 19.00 +/- 0.15
I 8.90 640 18.91 +/- 0.05
I 9.20 1080 19.15 +/- 0.05
I 9.54 1080 19.22 +/- 0.06
----------------------------------------------------------------------
Magnitudes were calibrated with respect to USNOB1 R2 and I.
GCN Circular 7629
Subject
GRB 080413B: Rapid PROMPT Observations
Date
2008-04-17T17:02:01Z (17 years ago)
From
Thomas Summers Brennan at UNC/GRB Group <bre@email.unc.edu>
T. Brennan, D. Reichart, M. Nysewander, A. LaCluyze, K. Ivarsen, J. A.
Crain, M. Schubel, A. Foster, J. Haislip, J. Styblova, and A. Trotter
report:
Skynet observed the localization of GRB 080413B (Stamatikos et al., GCN
7598) with four of the 16" PROMPT telescopes at CTIO beginning 27
seconds after the trigger (10 seconds after notification) in UBVRz'
We detect the afterglow (Stamatikos et al., GCN 7598) in BVRz'. At 42
seconds after the burst we measure B ~ 15.7 mag (calibrated to 2 USNO B1
stars), at 55 seconds we measure V ~ 15.4 mag (calibrated to 2 USNO B1
stars), and at 87 seconds we measure R ~ 15.4 mag (calibrated to 2 NOMAD
stars).