Gamma-ray Burst 111215B
(All information courtesy of the instrument teams.)
Previous IAU Circulars
Results of Observations
- GCN Circular #12698
K. Hurley, on behalf of the Mars Odyssey and MESSENGER GRB teams,
I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,
J. Goldsten, on behalf of the MESSENGER NS GRB team,
K. Yamaoka, M. Ohno, Y. Hanabata, Y. Fukazawa, T. Takahashi, M. Tashiro,
Y. Terada, T. Murakami, and K. Makishima on behalf of the Suzaku WAM team,
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C.
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and
S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration, intense GRB 111215B was observed by Konus-Wind,
Suzaku-WAM, MESSENGER (GRNS), and Mars Odyssey (HEND) at about 73686 s
UT (20:28:06). We have triangulated it to a preliminary, 3 sigma error
box whose coordinates are:
RA(2000), deg Dec(2000), deg
222.403 (14h 49m 37s) +16.439 (+16d 26' 21")
222.265 (14h 49m 04s) +16.514 (+16d 30' 51")
222.532 (14h 50m 08s) +16.665 (+16d 39' 53")
222.540 (14h 50m 10s) +16.364 (+16d 21' 49")
222.274 (14h 49m 06s) +16.212 (+16d 12' 43")
The error box area is 282 sq. arcmin, and its maximum
dimension is 31 arcmin.
This box can be improved.
The time history and spectrum will be given in a forthcoming GCN Circular.
A Swift ToO observation has been requested.
- GCN Circular #12700
O. M. Littlejohns (U. Leicester) reports on behalf of the Swift-XRT
We have analysed 4.9 ks of XRT data for the IPN-detected burst: GRB
111215B (Hurley et al. et al. GCN Circ. 12698), from 113.3 ks to 130.4
ks after the IPN trigger. The data are entirely in Photon Counting
(PC) mode. An X-ray source is detected within the IPN error circle.
The refined XRT position is RA, Dec = 222.3994, +16.45412 which is
RA (J2000): 14 49 35.86
Dec(J2000): +16 27 14.8
with an uncertainty of 3.7 arcsec (radius, 90% confidence). This
position is 55 arcsec from the IPN position. The light curve is
consistent with a constant source of mean count rate 2.6e-02 ct/sec. A
power-law fit gives an index of 1.9 (+0.9, -2.8).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.5 (+0.5, -0.3). The
best-fitting absorption column is 2 (+11, -1) x 10^20 cm^-2,
consistent with the Galactic value of 1.6 x 10^20 cm^-2 (Kalberla et
al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum is 4.9 x 10^-11 (5.1 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2 (+11, -1) x 10^20 cm^-2
Galactic foreground: 1.6 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.5 (+0.5, -0.3)
The results of the XRT-team automatic analysis are available at
This circular is an official product of the Swift-XRT team.
- GCN Circular #12701
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 GRB 111215B
(localized by IPN: Hurley et al., GCN 12698)
triggered Konus-Wind at T0=72682.720s UT (20:28:02.720)
The light curve shows multiple partly overlapping pulses
with the brightest peak at ~T0+12s.
A total duration of the burst is ~75 s.
The emission is seen up to ~8 MeV.
The Konus-Wind light curve of this GRB is available at
As observed by Konus-Wind the burst
had a fluence of 5.3(-1.1,+1.1)x10-5 erg/cm2,
and a 256-ms peak flux, measured from T0+11.776 s,
of 6.1(-0.6,+0.6)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+72.192 s)
is best fitted in the 20 keV - 10 MeV range
with the GRB (Band) model, for which:
the low-energy photon index alpha = -1.18 (-0.12, +0.18),
the high energy photon index beta = -2.3 (-0.6, +0.2),
the peak energy Ep = 250(-60, +65) keV,
chi2 = 88.2/88 dof.
The spectrum at the maximum count rate
(measured from T0+7.680 to T0+14.848 s)
is best fitted in the 20 keV - 10 MeV range
by a power law with exponential cutoff model, for which
alpha = -1.03 (-0.10, +0.11),
and Ep = 413(-57, +75) keV,
chi2 = 101.9/89 dof.
Fitting this spectrum by the GRB (Band) function yields
the same alpha and Ep with a high energy photon index
beta < -2.6 (chi2 = 101.9/88 dof).
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.
- GCN Circular #12702
S. R .Oates (MSSL-UCL) and C. J. Saxton (MSSL-UCL)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of the IPN-detected
burst: GRB 111215B, 31.5 hrs after the IPN trigger (Hurley et al. et al. GCN Circ. 12698)
No optical afterglow consistent with the XRT position (Littlejohns et al. et al. GCN Circ. 12700)
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 initial exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
u 113,256 130,435 4889 >21.4
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).
- GCN Circular #12705
W. Iwakiri, M. Tashiro, Y. Terada, T. Yasuda, K. Takahara, M. Asahina,
S. Kobayashi, A. Sakamoto (Saitama U.) Y. Hanabata, T. Uehara, T.
Kawano, K. Takaki, M. Mizuno, M. Ohno, Y. Fukazawa (Hiroshima U.), S.
Sugita (Nagoya U.), K. Yamaoka (Aoyama Gakuin U.), M. Kokubun, T.
Takahashi (ISAS/JAXA), Y. E. Nakagawa (Waseda U.), N. Ohmori, M.
Akiyama, M. Yamauchi (Univ. of Miyazaki), C-J. Chuang, Y. Urata, P. Tsai
(NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo),
The long bright GRB 111215B (localized by IPN: Hurley et al., GCN 12698)
triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 20:28:05.704 UT (=T0).
The observed light curve shows a multi-peaked structure starting at
T0-0.5 s, followed by a long weak tail seen up to T0+75 s with a
duration (T90) of about 61 seconds. The fluence in 100 - 1000 keV was
2.81(-0.06, +0.09) x 10^-5 erg/cm^2.
The 1-s peak flux measured from T0+13 s was
8.68 (-0.52, +0.36) photons/cm^2/s in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0-0.5 s
to T0+74.5 s is well fitted by a single power-law with a photon index of
2.05 (-0.06, +0.07) (chi^2 / d.o.f = 19.7/25).
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:
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Jochen Greiner, last update: 20-Dec-2011