Gamma-ray Burst 120624
(All information courtesy of the instrument teams.)
Previous IAU Circulars
Results of Observations
- GCN Circular #13377
D. Gruber (MPE), J. M. Burgess (UAH) and V. Connaughton (UAH)
report on behalf of the Fermi GBM Team:
"At 22:23:54.92 UT on 24 June 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120624B (trigger 362269436 / 120624933).
The on-ground calculated location, using the GBM trigger
data, is RA = 172.9, DEC = 6.5 (J2000 degrees,
equivalent to 11 h 31 m 36 s, 06 d 30 '), with an uncertainty
of 1 degree (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 71 degrees.
Moreover, this burst was bright enough to result in a Fermi spacecraft
autonomous rapid repoint (ARR) maneuver.
This burst was also independently detected by INTEGRAL SPI-ACS.
The GBM light curve consists of 3 bright, highly variable pulses
starting ~ 250 s prior to the GBM trigger. The first pulse
lasted ~100 s, the second pulse lasted ~120 s and the final pulse,
which triggered GBM, lasted ~50 s.
The event duration (T90) is about 271 s (50-300 keV).
GBM triggered on the third episode because the first and second
episode occurred during the brief part of the Fermi orbit at high
geomagnetic latitude where triggering is currently disabled
owing to particle activity and ensuing false triggers.
The time-averaged spectrum from T0-270 s to T0+22.5 s is
best fit by a Band function with Epeak = 566 +/- 20 keV,
alpha = -0.85 +/- 0.01, and beta = -2.36 +/- 0.08.
The event fluence (10-1000 keV) in this time interval is
(8.980 +/- 0.007)E-03 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+11.4 s in the 10-1000 keV band
is 846 +/- 17 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
- GCN Circular #13379
Giacomo Vianello (CIFS/SLAC), Daniel Kocevski (Stanford Univ.) report
on behalf of the Fermi LAT Team:
Fermi-LAT has detected high energy emission from the long, hard and
bright GRB 120624B in ground analysis. The GRB was triggered on by the
GBM on June 24, 2012 at 22:23:54.93 UTC, although the emission started
~250 seconds earlier (trigger 362269436, GCN 13377).
The best GBM position was \~70 deg off-axis for the whole duration of
the prompt emission (~270 seconds), outside of the Fermi/LAT nominal
field of view for the standard data analysis.
Using a non-standard data selection most sensitive in the tens-of-MeV
energy range and with a broader acceptance, we significantly detected
the burst between ~T0-250s and ~T0+20 s. The significance of the
excess corresponds to 10 sigma. The light curve shows 3 peaks, with a
total duration of \~270 s.
This burst was bright enough to result in a Fermi spacecraft
autonomous rapid repoint (ARR) maneuver, starting 100 s after the GBM
trigger. Thus, the GBM position entered the LAT field of view at
A preliminary maximum-likelihood analysis of the E>100MeV
P7TRANSIENT_V6 LAT data generated during the interval T0+100, T0+1.3
ks (until the GRB became occulted by the Earth) revealed a very
significant transient source, with a spectrum well described by a
power law of index -2.4 +/- 0.1 (68% c.l. statistical only). Using
this analysis, we obtained the best LAT on-ground localization of:
RA(J2000) = 170.73 deg
Dec(J2000) = 9.48 deg
with an error radius 0.45 deg (90% containment, statistical error
only), which is 3.6 deg from the best GBM localization.
The Zenith angle for this source was ~30 deg at the time of the
trigger, thus very far from the Earth Limb.
A Swift/ToO request has been submitted.
The Fermi-LAT point of contact for this burst is Daniel Kocevski
- GCN Circular #13381
S. D. Barthelmy (GSFC), J. Kennea (PSU), J. Racusin (GSFC)
report on behalf of the Swift Team:
At 22:19:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120624B (trigger=525068) (also detected by Fermi-GBM, Circ 13377
and Fermi-LAT, Circ 13379). There were no real-time notices
for this event because it occurred during a TDRSS outage (22:07 to 22:46),
so none of the normal sequence of real-time notices were available.
There was no automated slew to this BAT trigger because of a Moon constraint.
The BAT on-board calculated location is RA, Dec 170.94, 8.93 (J2000),
with an uncertainty of 3 arcmin (radius, 90% containment,
including systematic uncertainty). We are in the process of getting
the full data set downlinked, and will produce the nomal "refined"
circular when it becomes available.
- GCN Circular #13382
S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:
The long intense hard GRB 120624B
(GBM trigger 362269436: Gruber et al., GCN 13377;
Fermi/LAT detection: Vianello & Kocevski, GCN 13379)
triggered Konus-Wind at T0=80406.904s UT (22:20:06.904)
The light curve shows multiple pulses grouped to three main episodes.
A total duration of the burst is ~300 s.
We note a quasi-periodic light curve structure (with T~3.6s)
which is observed during the second bursting episode
(from ~T0+120s to ~T0+150s).
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
As observed by Konus-Wind the burst
had a fluence of 2.75(-0.1,+0.1)x10-4 erg/cm2,
and a 2.944-ms peak flux, measured from T0+235.28 s,
of 3.0(-0.6,+0.7)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum of the burst
(measured from T0 to T0+253.952 s)
is best fitted in the 20 keV - 10 MeV range
with the GRB (Band) model, for which:
the low-energy photon index alpha = -1.02 (-0.10, +0.12),
the high energy photon index beta = -2.6 (-2.0, +0.4),
the peak energy Ep = 530(-80, +90) keV,
chi2 = 82.7/86 dof.
The spectrum at the maximum count rate
(measured from T0+229.634 to T0+237.824 s)
is best fitted in the 20 keV - 10 MeV range
with the GRB (Band) model, for which:
the low-energy photon index alpha = -1.12 (-0.13, +0.21),
the high energy photon index beta = -2.3 (<-1.8),
the peak energy Ep = 1000(-450, +620) keV,
chi2 = 77.8/86 dof.
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.
- GCN Circular #13383
D. Gruber (MPE) reports on behalf of the Fermi GBM Team:
"The peak flux and fluence values reported for GRB 120624B
in GCN 13380 were erroneously calculated.
The correct numbers are as follows:
The fluence in the 10-1000 keV energy range
is (1.916 +/- 0.002)E-04 erg/cm^2.
This is consistent with the values reported
by Konus-Wind (Golenetskii et al. GCN 13382).
The 1-sec peak photon flux measured
in the 10-1000 keV band is 17.7 +/- 0.3 ph/s/cm^2.
We apologize for any inconvenience this has caused."
- GCN Circular #13384
T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
A. M. Parsons (GSFC), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 120624B (trigger #525068)
(Vianello, et al., GCN Circ. 13379; Barthelmy, et al., GCN Circ. 13381).
The BAT ground-calculated position is RA, Dec = 170.886, 8.933 deg which is
RA(J2000) = 11h 23m 32.6s
Dec(J2000) = +08d 56' 00.4"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 86%.
The mask-weighted light curve shows multiple overlapping episodes starting
from T-25 sec. There are two main episodes going from T-10 to T+70 sec with a
peak around T+35 sec, and the second episode starts T+120 sec and appears to
end around T+200 sec, with peaks at T+140 sec and T+170 sec. But the data ends
due to observing constraint and slewing to a pre-planned target. T90 (15-350 keV)
is greater than 192 sec due to the end of the mask-weighted light curve when
the source location left the field of view.
The time-averaged spectrum from T-15.1 to T+192.8 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.17 +- 0.03. The fluence in the 15-150 keV band is 2.83 +- 0.04 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+138.06 sec in the 15-150 keV band
is 5.5 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence
The results of the batgrbproduct analysis are available at
- GCN Circular #13385
A. S=E1nchez-Caso (Gualba Observatory, Barcelona) and A. J. Castro-Tirado
(IAA-CSIC Granada), on behalf of a larger collaboration, report:
Following the detection of GRB 120624B by Fermi/GBM, Fermi/LAT,
Konus/Wind and Swift/BAT (GCNC 13377, 13378, 13379 and 13381
respectively), we have imaged the field with the 0.36m f/7 telescope at
Gualba Observatory in Barcelona (Spain) starting on June 25 at 20:30 UT
(i.e. about 22 hr post-burst). Within the Swift/BAT 3=92 radius error box
optical afterglow candidate is identified for GRB 120624B. The limiting
magnitude in the 300-s unfiltered image (with the crescent moon only 9 deg
away) is 18.5.=94
This message can be quoted.
- GCN Circular #13387
D. Xu (WIS), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D. Malesani
(DARK/NBI), D. Gandolfi (ESTEC/ESA), G. Leloudas (OKC, Stockholm)
report on behalf of a larger collaboration:
We observed the Swift/BAT field of GRB 120624B (Gruber et al., GCN
13377; Vianello& Kocevski, GCN 13379; Sakamoto et al., GCN 13384)
using the 2.5m Nordic Optical Telescope (NOT) equipped with the ALFOSC
camera, at La Palma, Canary Islands. Observations started at 21:26 UT
on 2012-06-25 (i.e., 23.05 hr after the Fermi trigger) and a series of
SDSS r-band frames with a total exposure time of 1250s were obtained,
but were affected by the dusty calima from the Sahara desert.
No new optical source was detected within the refined BAT error circle
down to a 3-sigma limit of r(AB)~21.0.
- GCN Circular #13389
M. De Pasquale (UNLV), D. Gruber (MPE), J. M. Burgess (UAH), J. McEnery
(NASA/GSFC), S. T. Holland (STSCI), S. Razzaque (GMU/NRL) and J. L.
Racusin (NASA/GSFC), on behalf of the Swift, Fermi-GBM, and the Fermi-LAT
GRB 120624B, detected by Fermi-GBM (GCN 13377), Fermi-LAT (GCN 13379),
Swift-BAT (GCN 13381), and Konus-Wind (GCN 13382) has very high fluence
(1.9e-04 erg cm-2) and peak flux. The fluence of GRB 120624B in among the
top 1.5% of bursts detected by Swift-BAT and the top 0.55% detected by
The GRB position is unfortunately within the Swift Moon constraint.
Swift-XRT/-UVOT follow-up observations are planned when if comes out of
Moon constraint on June 27.4.
The refined BAT localization (GCN 13384) has an error radius of 1 arcmin
(90% containment). There are 13 SDSS galaxies with r>24 within the BAT
error circle. Analysis of the prompt emission suggests that the redshift
of this event is z > ~0.3 if this burst obeys the Amati relation, with
E_iso > ~4e+52 erg.
We strongly encourage follow-up observations of GRB 120624B.
- GCN Circular #13391
P. D'Avanzo (OaB/INAF), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), S. Campana (OaB/INAF), J. Gorosabel (IAA-CSIC), S. Covino (OaB/INAF), J.P.U. Fynbo (DARK/NBI), and C.C. Thoene (IAA-CSIC) report on behalf of a larger collaboration,
We observed the field of the very intense GRB 120426B detected by Fermi, Swift and Konus-Wind (Gruber et al., GCN 13377, Barthelmy et al. GCN 13381, Golenetskii et al. GCN 13382) with HAWKI at ESO's VLT (Paranal, Chile). Observations consisted of two epochs of 600s of integration in K-band covering the entire BAT error box (Sakamoto et al. GCN 13384). In the first epoch obtained 24.7 hr after the burst, we detect a faint source with a preliminary photometry K~20.8 compared to the 2MASS catalogue. This source is no longer visible in a second epoch 48.7 hr after the burst, where we estimate a 3-sigma limiting magnitude of K~21.6. The coordinates of the candidate nIR counterpart are (J2000 +/- 0.3"):
We note that this source falls North East of a galaxy at a projected distance of ~1.7" from the center of the galaxy.
We acknowledge excellent support from the Paranal staff, in particular Emanuela Pompei.
- GCN Circular #13393
P. Schady (MPE Garching), A. Nicuesa Guelbenzu, S. Klose, D. A. Kann
(TLS Tautenburg), M. Nardini (Universita' degli Studi Milano-Bicocca),
and J. Greiner (MPE Garching) report on behalf of the GROND team:
We observed the field of the bright GRB 120624B (Fermi/GBM trigger
362269436/120624933, Gruber et al., GCN 13377, 13383; Konus-Wind
detection, Golenetskii et al., GCN 13382; Swift trigger 525068,
Sakamoto et al., GCN 13384) simultaneously in g'r'i'z'JHK with GROND
(Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG/ESO
telescope at La Silla Observatory (Chile).
Observations started at 23:17 UT on 2012-06-25, about 23 hrs after the
GRB trigger and lasted for about 2 hrs. At the time of our
observations, the angular distance of the source position to the Moon
(last quarter) was just 10 degrees, significantly increasing the
background in our optical images.
In stacked images of the first 20min in the g'-band, of the first hour
in r', i' and z' and the whole 2 hr period of J, H and K
observations, we do not detect any new source at the position of the
NIR afterglow candidate (D'Avanzo et al., GCN 13391), nor within the
BAT error circle (Sakamoto et al., GCN 13384). The 3sigma limiting AB
magnitudes are as follows
g' > 23.3
r' > 24.0
i' > 23.5
z' > 23.4
J > 21.7
H > 21.1
K > 20.0
The galaxy close to the NIR afterglow candidate position mentioned in
D'Avanzo et al. (GCN 13391) is clearly detected in our J and H-band
images, with AB magnitudes J=20.9+/-0.2 and H=20.4+/-0.2.
The above limits are derived based on calibrating the optical and NIR
images against GROND zeropoints and 2MASS field stars respectively,
and are not corrected for the Galactic foreground extinction
corresponding to a reddening of E(B-V)=0.06 mag in the direction of
the burst (Schlegel et al. 1998).
- GCN Circular #13394
O.M. Littlejohns, P.A. Evans, K.L. Page (U. Leicester), A. Melandri, P.
D'Avanzo (INAF-OAB) and J.Racusin (GSFC) reports on behalf of the
We have analysed 10 ks of XRT data for GRB 120624B (Barthelmy et al.
GCN Circ. 13381), from 218.7 ks to 260.9 ks after the BAT trigger. The
data are entirely in Photon Counting (PC) mode. Inside the BAT refined
error circle (Sakamoto et al. GCN Circ. 13384) we find an uncatalogued
X-ray source (S1) at RA, Dec = 170.8845, +8.9283 which is equivalent
RA (J2000): 11 23 32.28
Dec(J2000): +08 55 42.0
with an uncertainty of 4.3 arcsec (radius, 90% confidence). This source
lies 40 arcsec from the NIR object reported by D'Avanzo et al. (GCN
Circ. 13391). We cannot determine at the present time whether the
source is fading, the count-rate is approximately 2e-3 ct/sec in XRT.
There is a second source (S2) at RA, Dec = 170.8670, +8.9319 which is
RA (J2000): 11 23 28.07
Dec(J2000): +08 55 54.8
with an uncertainty of 4.2 arcsec (radius, 90% confidence). This source
is 70 arcsec away from the BAT refined position, just outside the error
circle. This source is 35 arcsec from the NIR counterpart. This source
has a count-rate of approximately 1e-3 ct/sec, and again we cannot
measure variability at this time.
An image of the XRT field, with the two XRT sources, BAT error circle
and NIR source marked, is available at
Further observations are planned.
This circular is an official product of the Swift-XRT team.
- GCN Circular #13395
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), P. D'Avanzo (OaB/INAF),
S. Campana (OaB/INAF), J. Gorosabel (IAA-CSIC), S. Covino (OaB/INAF),
J.P.U. Fynbo (DARK/NBI), and C.C. Thoene (IAA-CSIC) report on behalf of
a larger collaboration,
In light of the recent XRT observation (Littlejohns et al., GCN13394) we
have performed further analysis of the HAWKI data reported by D'Avanzo
et al. (GCN 13391). Within the error circle of the XRT source we detect a
point-like source and a galaxy at the following coordinates (J2000 +/- 0.3"):
Galaxy 1A (RA, Dec): 11:23:32.08, +08:55:44.7
Point-like 1B (RA, Dec): 11:23:32.30, +08:55:42.5
We have performed image subtraction between our two K-band observations
and we detect no variability of any of these sources between the two epochs.
We also note that the galaxy is well detected in the SDSS with r=21.46 and a
has a photometric redshift of 0.57+/-0.07.
Our observations also cover the second XRT source that lies slightly outside
the BAT error circle. Within this region we detect 2 extended sources, with
coordinates (J2000 +/- 0.3"):
Galaxy 2 (RA, Dec): 11:23:28.17, +08:55:57.6
Galaxy 3 (RA, Dec): 11:23:28.07, +08:55:56.8
Again, no variability is found within the second XRT position. These are
detected as a single source in SDSS at r=21.55 and a photometric redshift
- GCN Circular #13397
A. A. Breeveld (MSSL/UCL), F. E. Marshall (NASA/GSFC) and J.Racusin
(GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 120624B
60hours 45mins after the BAT trigger (Barthelmy et al., GCN Circ. 13381).
No optical afterglow is found at either of the XRT positions
(Littlejohns et al. GCN 13394) nor the HAWKI position reported by
D'Avanzo et al. (GCN 13391) 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 summed exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 218726 218864 136 >20.9
white 218865 260947 7027 >23.1
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.06 in the direction of the
burst (Schlegel et al. 1998).
- GCN Circular #13398
O.M. Littlejohns, P.T. O'Brien, P.A. Evans, K. Page (UL) and J.Racusin (GSFC) reports on behalf of the Swift-XRT team:
Following the XRT observations of the BAT error circle for GRB 120624B reported in Littlejohns et al. (GCN Circ. 13394), we have compared the measured XRT flux of source S1 at 240 ks to that of bursts with similar or greater measured BAT fluence. Measurements of the XRT flux at approximately 240 ks for these bursts show that GRB 120624B lies at the faint end of the distribution of such bursts, should S1 prove to be the X-ray counterpart to GRB 120624B.
Further XRT observations are planned for Tuesday the 3rd July (2012), with a total exposure time of 10 ks, to check if either source S1 or S2 has faded.
This circular is an official product of the Swift-XRT team.
- GCN Circular #13400
S. Campana (INAF-OAB), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI),
A. J. Levan (U. Warwick) on behalf of a larger collaboration report:
we imaged for 10 ks the field of GRB 120624B (Gruber et al. 2012, GCN
13377) with the Chandra ACIS-S starting on June 30, 2012 8:56:22 UT.
Within the Swift/BAT 1 arcmin error circle (Barthelmy et al. 2012, GCN
we detect two sources, already reported by Swift/XRT (Littlejohns et al.
S1 source is detected with wavdetect at a (preliminary) position:
RA(J2000): 11 23 32.31
Dec(J2000):+08 55 42.8
The nominal positional error (90% c.l.) is 0.3 arcsec
(not including any statistical error).
The source is detected with 25 counts.
S2 source is detected with wavdetect at a (preliminary) position:
RA(J2000): 11 23 28.09
Dec(J2000):+08 55 57.0
The nominal positional error (90% c.l.) is 0.2 arcsec
(not including any statistical error).
The source is detected with 49 counts.
We do not detect any X-ray source at the position of
the NIR afterglow candidate (D'Avanzo et al. 2012, GCN13391).
We note that S1 is brighter than S2 in Swift/XRT observations.
The contrary occurs in the Chandra observation.
We extrapolate the Swift XRT rates based on the Swift/XRT spectrum
(Galactic column density of 3.6e20 cm-2, intrinsic column density of
2.4e21 cm-2 at redshift zero and a power law photon index of 2.52).
Assuming this spectrum for both sources, we predict
78 counts for S1 and 59 counts for S2, with large uncertainties due to
spectral modeling and statistics.
Despite this, the disagreement between Swift/XRT predictions (78 counts)
and Chandra observation (25 counts), likely indicate that S1 is the
We thank Chandra director (H. Tananbaum) for granting this observation
under the DDT program.
- GCN Circular #13413
A. Sakamoto, M. Tashiro, Y. Terada, W. Iwakiri, T. Yasuda, K. Takahara,
M. Asahina, S. Kobayashi, H. Ueno (Saitama U.),
M. Akiyama, N. Ohmori, M. Yamauchi (Univ. of Miyazaki),
K. Yamaoka, Y. E. Nakagawa (Waseda U.),
Y. Hanabata, T. Kawano, K. Takaki, Y.Tanaka, R. Nakamura, M. Ohno,
Y. Fukazawa (Hiroshima U.), S. Sugita (Nagoya U.), M. Kokubun,
T. Takahashi (ISAS/JAXA),=E3=80=80Y. Urata, P. Tsai (NCU), K. Nakazawa,
K. Makishima (Univ. of Tokyo),=E3=80=80on behalf of the Suzaku WAM team, =
The long GRB 120624B (Fermi/GRM; Gruber et al., GCN 13377,Fermi/LAT;
Vianello et al., GCN 13379,Konus-Wind; Golenetskii et al., GCN
13382,Swift/BAT; Sakamoto et al., GCN 13384)=E3=80=80was detected by the =
Wide-band All-sky Monitor (WAM) which covers an energy range of
50 keV - 5 MeV at 22:19:30.985 UT (=3DT0).
The observed light curve shows a multi-peaked structure starting at
T0+5 s, ending at T0+279 s, with a duration (T90) of about 274 seconds.
The fluence in=E3=80=80100 - 1000 keV was 1.22(-0.06 +0.02) x 10^-4 erg/c=
The 1-s peak flux measured from T0+274.5s was
6.88(-2.11 +0.27) photons/cm^2/s in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0-20s to
T0+285s is well fitted by a GRB Band model:
the low-energy photon index alpha: -1.03(-0.16 +0.20),
beta : -2.61 (-0.33, +0.20)
and the peak energy Epeak: 628(-73 +84) keV (chi^2/d.o.f =3D 72.1/50).
All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.
The light curves for this burst will be available at:
- GCN Circular #13421
M. Bremer, J. M. Winters, S. K=F6nig (IRAM Grenoble), A. de Ugarte Postigo
and A. J. Castro-Tirado (IAA-CSIC Granada) on behalf of a larger
"Following the detection of the intense GRB 120624B by different
spacecraft (GCNC 13379, 13381,13382), we have conducted follow-up
observations at 3 mm with the PdBI on June 28 and July 2. Consistent
with the position of the proposed X-ray afterglow (GCNC 13394, 13400) we
detect a 1 mJy source (6 sigma). Observations are ongoing".
This message can be quoted.
- GCN Circular #13474
C. Bathurst (U. South Florida), D. A. Frail (NRAO) and S. B. Cenko (UC
Berkeley) report on behalf of a larger collaboration:
We have observed the field of the potential X-ray afterglow (GCN 13400,
13394) of the Fermi GBM (GCN 13377) and LAT (GCN 13379) GRB 120624B with
the VLA. In observations taken on 2012 July 10.00 UT, at center
frequencies of 5 GHz and 14 GHz, we find an unresolved radio source
coincident with the position of the claimed X-ray afterglow (GCN 13400).
The radio source is detected at 5-6 sigma significance and it has a
rising spectrum consistent with the extrapolation of the 3mm PdBI
detection (GCN 14321). Further 5 GHz observations were also made on June
26, June 29 and July 11. The 5 GHz flux density of the radio source shows
no evidence for variability through these 4 epochs.
Further observations are planned.
- 1309.1167 from 6 Sep 13
A. de Ugarte Postigo et al.: The obscured hyper-energetic GRB 120624B hosted by a luminous compact galaxy at z = 2.20
Gamma-ray bursts are the most luminous explosions that we can witness in the Universe. Studying the most extreme cases of these phenomena
allows us to constrain the limits for the progenitor models. In this Letter, we study the prompt emission, afterglow, and host galaxy of GRB
120624B, one of the brightest GRBs detected by Fermi, to derive the energetics of the event and characterise the host galaxy in which it was
produced. Following the high-energy detection we conducted a multi-wavelength follow-up campaign, including near-infrared imaging from
HAWKI/VLT, optical from OSIRIS/GTC, X-ray observations from the Chandra X-ray Observatory and at sub-millimetre/millimetre wavelengths from
SMA. Optical/nIR spectroscopy was performed with X-shooter/VLT. We detect the X-ray and nIR afterglow of the burst and determine a redshift of
z = 2.1974 +/- 0.0002 through the identification of emission lines of [OII], [OIII] and H-alpha from the host galaxy of the GRB. This implies
an energy release of Eiso = (3.0+/-0.2)x10^54 erg, amongst the most luminous ever detected. The observations of the afterglow indicate high
obscuration with AV > 1.5. The host galaxy is compact, with R1/2 < 1.6 kpc, but luminous, at L ~ 1.5 L* and has a star formation rate of 91 +/-
6 Msol/yr as derived from H-alpha. As other highly obscured GRBs, GRB 120624B is hosted by a luminous galaxy, which we also proof to be
compact, with a very intense star formation. It is one of the most luminous host galaxies associated with a GRB, showing that the host galaxies
of long GRBs are not always blue dwarf galaxies, as previously thought.
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Jochen Greiner, last update: 06-Sep-2013