GRB 121123A
GCN Circular 14200
Subject
GRB 121123A: optical observations
Date
2013-02-13T16:34:45Z (13 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
Yu. Krugly (Institute of Astronomy of Kharkiv National University),
R.Inasaridze, O. Kvaratskhelia(Abastumani Astrophysical Observatory),
I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB
follow-up collaboration:
We observed the field of the Swift GRB 121123A (Helder et al., GCN
13982) with AC-32 (0.7m Maksutov) telescope of Abastumani Observatory,
starting on Nov. 23 (UT) 15:18. We took several unfiltered images of 180
s exposure. We clearly detected the afterglow (Helder et al., GCN 13982;
Zhao et al., GCN 13983) in every single image. The photometry of the
stacked images is based on USNO-B1.0 stars (R2):
Start, T0+, Filter, Exp., OT
(UT) (mid),days
15:18:28 0.2229 none 4x180 19.01 +/- 0.10
15:33:10 0.2337 none 4x180 18.96 +/- 0.09
15:48:15 0.2448 none 4x180 18.88 +/- 0.08
16:02:57 0.2551 none 4x180 19.17 +/- 0.11
16:02:57 0.2642 none 4x180 18.94 +/- 0.10
16:28:40 0.2729 none 4x180 19.06 +/- 0.11
GCN Circular 14088
Subject
GRB 121123A: NIKA (New IRAM KID Arrays) millimetre observations at the 30-m Pico Veleta telescope
Date
2012-12-16T09:29:40Z (13 years ago)
From
Alessandro Monfardini at CNRS,Grenoble <alessandro.monfardini@grenoble.cnrs.fr>
A. Monfardini (I. N��el, Grenoble), F.-X. D��sert (IPAG, Grenoble),
N. Ponthieu (IPAG, Grenoble), R. Adams (LPSC, Grenoble), M. Calvo (I.
N��el, Grenoble), J. Macias-Perez (LPSC, Grenoble), A. Catalano (LPSC,
Grenoble), S. Leclercq (IRAM, Grenoble), P. Mauskopf (Arizona State U. &
Cardiff U.), A. Benoit (I. N��el, Grenoble), on behalf of the NIKA
collaboration, report:
"During a technical run, we observed the
position of GRB 121123A (E. A. Helder et al., GCN 13982) with the NIKA
instrument being commissioned at the IRAM 30-m at Pico Veleta.
Observations were accomplished between 15h and 16h UT on 24th November
2012 (mean time 29.5 hours after the burst), under poor observing
conditions (tau225GHz ~ 0.35) and at relatively low elevation (35 deg).
In roughly 40 minutes effective time on source, we do not detect the
afterglow at the position given by D. Xu et al., GCN 13986. The
following 3-sigma upper limits were derived:
U.L. 3 mJy at 150 GHz
(99.7% C.L.)
U.L. 40 mJy at 240 GHz (99.7% C.L.), strongly limited by
unstable weather conditions
NIKA is a multi-hundred-pixels dual-band
continuum instrument operating simultaneously at central frequencies of
150 GHz (bandwidth 40 GHz) and 240 GHz (bandwidth 60 GHz). It is the
first instrument based on the intrinsically multiplexable KID (Kinetic
Inductance Detectors) technology installed permanently at a telescope.
For more information about the instrument and the future project NIKA-2,
see A. Monfardini et al., ApJS 194, Issue 2, id. 24 (2011).
We thank
the IRAM Granada and Grenoble staff for their outstanding support
before, during and after the NIKA run."
GCN Circular 14006
Subject
GRB 121123A: Suzaku WAM observation of the prompt emission
Date
2012-11-27T15:03:15Z (13 years ago)
From
Makoto Tashiro at Saitama U/Swift <tashiro@phy.saitama-u.ac.jp>
T.Yasuda, M. Tashiro, Y. Terada, W. Iwakiri, K. Takahara,
M. Asahina, S. Kobayashi, A. Sakamoto, Y. Ishida,
H. Ueno, S. Sugimoto (Saitama U.),
M. Akiyama, N. Ohmori, E. Mochinaga, M. Yamauchi (Univ. of Miyazaki),
K. Yamaoka, Y. E. Nakagawa (Waseda U.),
Y. Hanabata, T. Kawano, K. Takaki, R. Nakamura, Y.Tanaka, M. Ohno,
Y. Fukazawa (Hiroshima U.), S. Sugita (Nagoya U.), M. Kokubun, T.
Takahashi (ISAS/JAXA),
Y. Urata, P. Tsai (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo),
on behalf of the Suzaku WAM team, report:
The long GRB 121123A (Helder et al., GCN 13982; Zhao et al., GCN 13983;
Yurkov et al., GCN 13984; Foley, GCN 13985; Xu et al., GCN 13986;
Guziy et al., GCN 13987; Volnova et al., GCN 13988; Melandri et al.,
GCN 13989; Barthelmy et al., GCN 13990; Evans et al., GCN 13991;
Schmidl et al., GCN 13992) was detected by the the Suzaku Wide-band
All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV
at 10:06:00 UT (=T0).
The observed light curve shows a single peak followed by a long weak
tail seen up to T0+74 s with a duration (T90) of about 73 seconds.
The fluence in 100 - 1000 keV was 7.72 (+0.44/-7.11) x 10-6 erg/cm^2.
The 1-s peak flux measured from T0+33 s was
0.74 (+0.54/-0.34) photons/cm^2/s in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0+1 s to
T0+74 s is well fitted by a single power-law with a photon index
of 3.29 (+0.64/-0.50) (chi2/d.o.f = 4.7/11).
The light curves with 1-sec time resolution for this burst will be
appeared at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html
GCN Circular 14003
Subject
GRB 121123A: Swift/UVOT Observations
Date
2012-11-26T22:25:09Z (13 years ago)
From
Stephen Holland at STScI <sholland@stsci.edu>
S. T. Holland (STScI) and
E. A. Helder (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB
121123A starting 131 s after the BAT trigger (Helder et al., 2012,
GCNC 13982). The refined UVOT position is
RA (J2000) 20:29:16.30 = 307.31792 (deg)
Dec (J2000) -11:51:35.6 = -11.85989 (deg)
with an estimated uncertainty of 0.44 arcsec (radius, 90% confidence,
statistical + systematic). We observe a slow decay of the optical
afterglow, consistent with that reported by Xu et al., (2012, GCNC
13986). The afterglow is weakly detected in white at approximately 40
ks after the BAT trigger. However, the UVOT photometry is affected by
a bright (B ~ 14 mag) star (USNO B1.0 0781-0714667) located
approximately 22 arcsec north of the afterglow, so the late-time
behavior of the optical afterglow's light curve requires further
analysis. Preliminary UVOT photometry, and 3-sigma upper limits, for
the afterglow are presented below.
------------------------------------------------------
Filter TSTART TSTOP Exposure Mag Err
------------------------------------------------------
white (fc) 131 281 147 19.43 0.15
u (fc) 289 539 246 19.35 0.23
white (fc) 869 1019 147 19.13 0.12
------------------------------------------------------
v 619 1070 58 18.29 0.33
b 546 1169 58 19.12 0.29
u 695 1145 39 18.58 0.32
uvw1 669 18,011 2137 >21.5
uvm2 645 17,104 1376 >21.3
uvw2 595 22,980 1376 >21.5
white 570 590 19 >19.7
------------------------------------------------------
The detection in the UVOT u band, combined with the non-detection
in the UVOT uvw1 band, is consistent with GRB 121123A having a
redshift of approximately 1.5 < z < 3.4.
The quoted magnitudes and upper limits have not been corrected for
the Galactic extinction along the line of sight to this burst of
E_{B-V} = 0.05 mag (Schlafly et al. 2011, ApJS, 737, 103). The
photometry is in the UVOT photometric system (Breeveld et al. 2011,
AIP Conf. Proc. 1358, 373).
GCN Circular 13992
Subject
GRB 121123A: GROND observations
Date
2012-11-24T03:38:49Z (13 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
S. Schmidl, A. Nicuesa Guelbenzu, S. Klose (all TLS Tautenburg), and J.
Greiner (MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 121123A (Swift trigger 539358; Helder et al.,
GCN 13982; Fermi trigger 375357963 / 121123421; Foley et al., GCN 13985)
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 00:20 UT on Nov 24, about 15 hours after the GRB
trigger. They were performed at an average seeing of 1.3" and at an
average airmass of 1.9. The optical afterglow (Helder et al., GCN 13982;
Zhao et al., GCN 13983; Xu et al., GCN 13986; Guziy et al., GCN 13987) is
clearly detected in all bands. Based on 1500 s of total exposures in
g'r'i'z' and 1200 s in JHK, we measure the following preliminary AB
magnitudes at a midtime of 15.25 hrs after the burst:
g' = 20.8 +/- 0.1,
r' = 20.3 +/- 0.1,
i' = 19.9 +/- 0.1,
z' = 19.8 +/- 0.1,
J = 19.2 +/- 0.1,
H = 18.9 +/- 0.1,
K = 18.6 +/- 0.2,
calibrated against GROND zeropoints and 2MASS stars. The SED can be fit
with a power law with a slope of beta = 1.2 +/ -0.1 and a g-band affected
by a dropout with a redshift of z = 2.7 +/- 0.3, taking into acount a
Galactic reddening along the line of sight of E_(B-V)= 0.05 mag (Schlegel
et al.1998). We note that the data can also be fit with a modest host
extinction and no dropout-affected g-band. At present we cannot solve this
ambiguity.
GCN Circular 13991
Subject
GRB 121123A: Enhanced Swift-XRT position
Date
2012-11-24T02:23:43Z (13 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 12254 s of XRT Photon Counting mode data and 15 UVOT
images for GRB 121123A, 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 = 307.31813, -11.86023 which is equivalent
to:
RA (J2000): 20h 29m 16.35s
Dec (J2000): -11d 51' 36.8"
with an uncertainty of 1.4 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 13990
Subject
GRB 121123A: Swift-BAT refined analysis
Date
2012-11-24T02:20:12Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), E. A. Helder (PSU),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(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 121123A (trigger #539358)
(Helder, et al., GCN Circ. 13982). The BAT ground-calculated position is
RA, Dec = 307.334, -11.873 deg, which is
RA(J2000) = 20h 29m 20.2s
Dec(J2000) = -11d 52' 24.3"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 82%.
The mask-weighted light curve shows the burst starting off at a weak level
at ~T-90 sec, with the triggering peak at ~T+10 sec, then a level period
until ~T+200 sec with the onset of a large FRED peak extending out
to ~T+700 sec. T90 (15-350 keV) is 317 +- 14 sec (estimated error
including systematics).
The time-averaged spectrum from T-6.34 to T+419.00 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 0.96 +- 0.20,
and Epeak of 65.0 +- 5.1 keV (chi squared 45.4 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 1.5 +- 0.1 x 10^-5 erg/cm2
and the 1-sec peak flux measured from T+232.56 sec in the 15-150 keV band is
2.6 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.78 +- 0.04 (chi squared 101.58 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/539358/BA/
GCN Circular 13989
Subject
GRB 121123A: Swift-XRT refined Analysis
Date
2012-11-24T02:17:12Z (13 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), G. Stratta
(ASDC), J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), A.P.
Beardmore (U. Leicester), P.A. Evans (U. Leicester), O.M. Littlejohns
(U. Leicester) and E.A. Helder report on behalf of the Swift-XRT team:
We have analysed 10 ks of XRT data for GRB 121123A (Helder et al. GCN
Circ. 13982), from 129 s to 23.8 ks after the BAT trigger. The data
comprise 669 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The refined XRT position is RA, Dec =
307.3183, -11.85898 which is equivalent to:
RA (J2000): 20 29 16.39
Dec(J2000): -11 51 32.3
with an uncertainty of 3.5 arcsec (radius, 90% confidence).
The late-time light curve (from T0+4.7 ks) can be modelled with a
power-law decay with a decay index of alpha=0.50 (+/-0.09).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.448 (+0.023, -0.022). The
best-fitting absorption column is 8.9 (+/-0.6) x 10^20 cm^-2, in
excess of the Galactic value of 4.0 x 10^20 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 1.97 (+/-0.11) and a
best-fitting absorption column of 5.8 (+2.3, -1.8) x 10^20 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.6 x 10^-11 (4.2 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 5.8 (+2.3, -1.8) x 10^20 cm^-2
Galactic foreground: 4.0 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.97 (+/-0.11)
If the light curve continues to decay with a power-law decay index of
0.50, the count rate at T+24 hours will be 0.051 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x
10^-12 (2.1 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/00539358.
This circular is an official product of the Swift-XRT team.
GCN Circular 13988
Subject
GRB 121123A: optical observations
Date
2012-11-24T01:50:55Z (13 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (SAO MSI, IKI), A. Stepura (UAFO), A. Matkin (UAFO), D.
Erofeev (UAFO), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf
of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 121123A (Helder et al., GCN
13982) with VT-50 (0.5-m) telescope and GAS-250 of UAFO/ISON-Ussuriysk
observatory starting on Nov. 23 (UT) 10:10:15, i.e. 6 minutes after
burst trigger. We took several unfiltered images of 30 s. We do not
detect detect afterglow (Helder et al., GCN 13982; Zhao et al., GCN
13983) in a stacked images. Preliminary photometry of a stacked image
obtained with VT-50 is based on USNO-B1.0 stars (R2):
T_start T0+, Filter, exposure, UL (3 sigma)
(UT) mid (d) (s)
10:10:15 0.02793 none 90x30 18.1
GCN Circular 13987
Subject
GRB 121123A: BOOTES-4 and IAC80 optical observations
Date
2012-11-23T22:40:22Z (13 years ago)
From
Javier Gorosabel at IAA-CSIC <jgu@iaa.es>
S. Guziy (Mykolaiv Nat. Univ.), R. Sanchez-Ramirez (IAA-CSIC), L.
Monteagudo Narvion (IAC), O. Lara, M. Jelinek (IAA-CSIC), P. Kubanek (IP
AS CR), Y. Fan, X. Zhao, J. Bai, C. Wang, Y. Xin (Yunnan National
Astronomical Observatory), Chenzhou Cui (Beijing National Astronomical
Observatory), R. Cunniffe, A.J. Castro-Tirado, J.C. Tello and J. Gorosabel
(IAA-CSIC), on behalf of a larger collaboration, report:
We have observed the GRB 121123A optical afterglow (GCN 13982, Helder et
al.) with the 0.6m BOOTES-4/MET robotic telescope at the Lijiang
Astronomical Observatory (China) and with the 0.82m IAC80 telescope
(Tenerife, Spain). The afterglow is detected as follows:
Tel. Date Nov To-Tgrb Texp Filter Mag(Vega)
UT-start (hr) (s)
--------------------------------------------------------
BOOTES-4 23.5196 2.43 5x120 r 18.87 +/- 0.15
BOOTES-4 23.5711 3.66 5x120 r 19.01 +/- 0.15
IAC80 23.7853 8.80 4x300 I 18.90 +/- 0.12
Our measurements confirm the shallow decay reported by Xu et al. (GCN 13986).
GCN Circular 13986
Subject
GRB 121123A: NOT optical observations
Date
2012-11-23T21:31:18Z (13 years ago)
From
Dong Xu at DARK/NBI <dong.dark@gmail.com>
D. Xu, T. Kruehler, D. Malesani (DARK/NBI), G. Leloudas (OKC Stockholm
and DARK/NBI) I. Ilyin (AIP), J. Clasen (NOT), P. Jakobsson (U.
Iceland), J. P. U. Fynbo (DARK/NBI) report on behalf of a larger
collaboration:
We observed the field of GRB 121123A (Helder et al., GCN 13982) using
the 2.5m Nordic Optical Telescope (NOT) equipped with StanCam.
Observations started at 20:03:43 UT on 2012-11-23 (i.e., 9.972 hr
after the BAT trigger) and 5x300s R-band frames were obtained with
mid-time of 10.218 hr post-trigger.
The afterglow is clearly detected in the stacked image at coordinates
R.A.(J2000)= 20:29:16.289
Dec.(J2000)=-11:51:35.87
with R=19.65+/-0.03 mag, calibrated with the #0781-0714632 star
(R1=R2=17.17 mag with a scatter of 0.3 mag) in the USNO B1 catalog.
We note that our measurement is only modestly fainter than the one
reported by Zhao et al. (GCN 13983) at 1.5 hr after the BAT trigger,
indicating a shallow decay or an irregular light curve.
GCN Circular 13985
Subject
GRB 121123A: Fermi GBM observation
Date
2012-11-23T19:16:43Z (13 years ago)
From
Suzanne Foley at MPE <sfoley@mpe.mpg.de>
S. Foley (UCD)
reports on behalf of the Fermi GBM Team:
"At 10:06:00.59 UT on 23 November 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located the second emission episode of GRB 121123A
(trigger 375357963 / 121123421) which was also detected by the
Swift/BAT (Helder et al. 2012, GCN 13982,
http://gcn.gsfc.nasa.gov/notices_s/sw00539358000msbx.gif).
The emission detected by GBM is contemporaneous with the UVOT
observation of an afterglow candidate for GRB 121123A reported by
Helder et al.
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 85 degrees.
The GBM light curve consists of a single peak with a long tail
with a duration (T90) of about 102 s (50-300 keV).
The time-averaged spectrum from T0+3.1 s to T0+106.5 s is
well fit by a Band function with Epeak = 85 (+/-3) keV,
alpha = -0.25 (+/-0.09), and beta = -3.0 (+0.2/-0.3).
The event fluence (10-1000 keV) in this time interval is
(2.20 +/- 0.08)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+32.6 s in the 10-1000 keV band
is 4.00 +/- 0.25 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 13984
Subject
GRB 121123A: MASTER-NET optical limit
Date
2012-11-23T12:37:39Z (13 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski,
N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov,
D.Denisenko, A.Sankovich
Sternberg Astronomical Institute, Moscow State University
K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University
V.Krushinski, I.Zalozhnih, A. Popov
Ural Federal University, Kourovka
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory
Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in Blagoveschensk was pointed to the GRB121123A 100 sec after
GRB time at 2012-11-23 10:04:21.926 UT.
On our first (20s exposure) set we haven`t found optical transient
within SWIFT error-box (Helder et. al., GCN13982).
The 5-sigma upper limit has been about 16.5 mag
The field was observed at large (more than 70 deg.) zenith distance.
The message may be cited.
GCN Circular 13983
Subject
GRB 121123A: GMG optical observation
Date
2012-11-23T12:32:40Z (13 years ago)
From
Xiao-hong Zhao at Yunnan Obs <zhaoxiaohong78@gmail.com>
X.-H. Zhao (YNAO), C. -J. Wang, J.-R. Mao (KASI/YNAO), J.-M. Bai
(YNAO) report on behalf of a larger collaboration:
We observed the field of GRB 121123A (Helder et al., GCN 13982) with 2.4m Gao-Mei-Gu (GMG) telescope. Observations
started at ~1.5 hrs after the burst. The optical afterglow of this burst was detected. The preliminary magnitude was R~19.2.
observation is on going.
We thank the GMG staff, especially Hong-Yan Gao, and De-Qing Wang for doing these observations.
GCN Circular 13982
Subject
GRB 121123A: Swift detection of a burst with optical counterpart
Date
2012-11-23T10:17:59Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
E. A. Helder (PSU), S. D. Barthelmy (GSFC), V. D'Elia (ASDC),
P. A. Evans (U Leicester), F. E. Marshall (NASA/GSFC),
C. J. Mountford (U Leicester), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Swift Team:
At 10:02:41 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 121123A (trigger=539358). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 307.362, -11.860 which is
RA(J2000) = 20h 29m 27s
Dec(J2000) = -11d 51' 34"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a single peak
structure with a duration of about 25 sec. The peak count rate
was ~1200 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 10:04:44.3 UT, 123.0 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 307.3179, -11.8590 which is equivalent to:
RA(J2000) = +20h 29m 16.30s
Dec(J2000) = -11d 51' 32.4"
with an uncertainty of 5.4 arcseconds (radius, 90% containment). This
location is 155 arcseconds from the BAT onboard position, within the
BAT error circle. No event data are yet available to determine the
column density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 1.30e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 131 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 20:29:16.31 = 307.31794
DEC(J2000) = -11:51:35.4 = -11.85983
with a 90%-confidence error radius of about 0.67 arc sec. This position is 3.0
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.34 with a 1-sigma error of about 0.17. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.05.
Burst Advocate for this burst is E. A. Helder (helder AT psu.edu).
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.)