GRB 141220A
GCN Circular 17653
Subject
GRB 141220A: GMG observation limit
Date
2015-03-29T11:09:44Z (11 years ago)
From
Jirong Mao at Yunnan Obs <jirongmao_obs@ynao.ac.cn>
J. Mao, B. Lun and J.-M. Bai (YNAO) report:
We observed the field of GRB 141220A (Cummings et al., GCN 17196) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG)
station of Yunnan Observatory. Observations began from UT 22:28:38.1 20, Dec., 2014 (about 18.4 hours after the trigger).
We did not detect the optical counterpart down to a limit of r'~21.0.
We thank Dr. A., de Ugarte Postigo for his kind suggestion and disucssion. J. Mao apologizes for this very later GCN circular submission.
GCN Circular 17215
Subject
GRB 141220A: MITSuME Akeno upper limits
Date
2014-12-22T07:06:48Z (12 years ago)
From
Taketoshi Yoshii at Tokyo Tech <yoshii.t.ac@m.titech.ac.jp>
Y. Yano, T. Yoshii, Y. Saito, Y. Tachibana, H. Ohuchi,
S. Kurita, Y. Ono, T. Fujiwara, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We observed the field of GRB 141220A (J. R. Cummings et al., GCN Circular #17196) with the
optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm
telescope of Akeno Observatory, Yamanashi, Japan.
The observation started on 2014-12-20 15:16:22 UT (~9.2 h after the burst).
We did not find any new point source within the refined XRT error circle
(B. P. Gompertz., GCN Circular #17203) in all the three bands.
The measured magnitudes are listed below.
T0+[sec] MID-UT T-EXP[sec] g' Rc Ic
-----------------------------------------------------------------------------
36707 18:07:29 8460 >21.4 >20.8 >20.4
-----------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.
GCN Circular 17207
Subject
Konus-Wind observation of GRB 141220A
Date
2014-12-21T12:57:37Z (12 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lyssenko, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 141220A (Swift-BAT trigger #621915:
Cummings et al., GCN 17196; Stamatikos et al., GCN 17202;
Fermi-GBM observation: Yu, GCN 17205)
triggered Konus-Wind at T0=21771.666 s UT (06:02:51.666).
The KW light curve shows a single emission episode lasting from ~T0-0.5 s
to ~T0+7.5 s. The emission in this episode is visible up to ~4 MeV.
As observed by Konus-Wind, the burst had a fluence
of 4.7(-0.4,+0.5)x10^-6 erg/cm2, and a 64-ms peak flux,
measured from T0, of 2.2(-0.4,+0.5)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 15 MeV range
by the cutoff power law with the following model parameters:
the photon index alpha = -0.55(-0.26,+0.30),
and the peak energy Ep = 139(-14,+18) keV,
chi2 = 83/98 dof.
Fitting this spectrum with the Band model yields the same
values of alpha and Ep and an upper limit on beta of -2.0
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB141220_T21771/
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 17205
Subject
GRB 141220A: Fermi GBM observation
Date
2014-12-21T04:24:48Z (12 years ago)
From
Hoi-Fung Yu at MPE <sptfung@mpe.mpg.de>
H.-F. Yu (MPE) reports on behalf of the Fermi GBM Team:
"At 06:02:52.49 UT on 20 Dec 2014, the Fermi Gamma-Ray Burst Monitor triggered
and located GRB 141220A (trigger 141220252/ 141220252), which was also detected
by Swift (Cummings et al. 2014, GCN 17196). The GBM on-ground location, using
the Fermi GBM trigger data, is consistent with the Swift location. The trigger
resulted in an Autonomous Repoint Request (ARR) that was accepted and the
spacecraft slewed to the GBM in-flight location. The angle from the Fermi LAT
boresight is about 47 degrees.
The GBM light curve consists of two main pulses with a duration (T90) of about
7.6 s (50-300 keV). The time-averaged spectrum from T0-1.920 s to T0+8.320 s is
best fit by a power law function with an exponential high-energy cutoff. The
power law index is -0.80 +/- 0.05 and the cutoff energy, parameterized as Epeak,
is 180 +/- 9 keV.
The event fluence (8-1000 keV) in this time interval is
(5.23 +/- 0.15)E-06 erg/cm^2. The 1.024-sec peak photon flux measured starting
from T0+0.128 s in the 8-1000 keV band is 12.0 +/- 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 17204
Subject
GRB 141220A: MITSuME Okayama upper limits
Date
2014-12-20T23:57:05Z (12 years ago)
From
Daisuke Kuroda at OAO/NAOJ <dikuroda@oao.nao.ac.jp>
D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of MITSuME and OISTER collaboration:
We observed the field of GRB 141220A (Cummings et al., GCNC 17196)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.
The observation started on 2014-12-20 16:27:31 UT (~10.4 h after the burst)
We could not detect the previously reported afterglow (Cummings et al., GCNC
17196; Gorosabel et al., GCNC 17197; de Ugarte Postigo et al., GCNC 17198) in
all the three bands.
Three sigma upper limits of the OT are listed below.
We used SDSS-DR7 catalog for flux calibration.
#T0+[day] MID-UT T-EXP[sec] g' Rc Ic
-----------------------------------------------------
0.47547 17:27:32 5940.0 >19.8 >19.9 >19.0
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
GCN Circular 17203
Subject
GRB 141220A: Swift-XRT refined Analysis
Date
2014-12-20T20:23:04Z (12 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
B.P. Gompertz (U. Leicester), M. de Pasquale (INAF-IASFPA), A. Maselli
(INAF-IASFPA), A. Melandri (INAF-OAB), M.C. Stroh (PSU), D.N. Burrows
(PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester) and J.R. Cummings report on behalf of the Swift-XRT team:
We have analysed 6.8 ks of XRT data for GRB 141220A (Cummings et al.
GCN Circ. 17196), from 87 s to 36.3 ks after the BAT trigger. The
data comprise 42 s in Windowed Timing (WT) mode (the first 8 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode. The refined XRT position is RA, Dec = 195.0653, +32.1466
which is equivalent to:
RA (J2000): 13 00 15.66
Dec(J2000): +32 08 47.9
with an uncertainty of 3.6 arcsec (radius, 90% confidence).
The late-time light curve (from T0+5.6 ks) can be modelled with a
power-law decay with a decay index of alpha=1.38 (+0.26, -0.23).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.81 (+0.21, -0.20). The
best-fitting absorption column is 8.3 (+5.9, -5.1) x 10^20 cm^-2, in
excess of the Galactic value of 1.3 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 3.7 x 10^-11 (4.2 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 8.3 (+5.9, -5.1) x 10^20 cm^-2
Galactic foreground: 1.3 x 10^20 cm^-2
Excess significance: 2.3 sigma
Photon index: 1.81 (+0.21, -0.20)
If the light curve continues to decay with a power-law decay index of
1.38, the count rate at T+24 hours will be 2.6 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.5 x
10^-14 (1.1 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00621915.
This circular is an official product of the Swift-XRT team.
GCN Circular 17202
Subject
GRB 141220A: Swift-BAT refined analysis
Date
2014-12-20T16:48:39Z (12 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <james.r.cummings@nasa.gov>
M. Stamatikos (OSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings, N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), J. Tueller (GSFC),
T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-61 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 141220A (trigger #621915) (Cummings, et al.,
GCN Circ. 17196). The BAT ground-calculated position is RA, Dec = 195.058, 32.146
deg which is:
RA(J2000) = 13h 00m 14.0s
Dec(J2000) = +32d 08' 46.4"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 19%.
The mask-weighted light curve shows two peaks at about T+1 and T+3 seconds,
with an exponential decline noticeable out to ~T+20 seconds. T90 (15-350 keV)
is 7.21 +- 0.48 sec (estimated error including systematics).
The time-averaged spectrum from T-0.91 to T+7.30 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 0.62 +- 0.38,
and Epeak of 117.4 +- 45.1 keV (chi squared 56.50 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 2.6 +- 0.1 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T-0.13 sec in the 15-150 keV band is
8.9 +- 0.7 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.30 +- 0.08 (chi squared 67.35 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/621915/BA/
GCN Circular 17201
Subject
GRB 141220A: Swift/UVOT Detection
Date
2014-12-20T16:08:45Z (12 years ago)
From
Frank Marshall at GSFC <femarsha@khamseen.gsfc.nasa.gov>
F. E. Marshall (NASA/GSFC) and J. R. Cummings (NASA/UMBC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 141220A
597 s after the BAT trigger (Cummings et al., GCN Circ. 17196).
There were also other exposures when the spacecraft attitude
was not stable.
A source consistent with the optical position
Gorosabel et al. (GCN Circ. 17197)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 13:00:15.76 = 195.06565 (deg.)
Dec (J2000) = +32:08:47.0 = 32.14639 (deg.)
with an estimated uncertainty of 0.45 arc sec. (radius, 90% confidence).
Preliminary detections using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 597 617 19 17.30 � 0.07
v 647 839 39 17.65 � 0.16
b 573 593 20 17.58 � 0.13
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 17200
Subject
GRB 141220A: Photometry from OSIRIS/GTC
Date
2014-12-20T11:08:46Z (12 years ago)
From
Antonio de Ugarte Postigo at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), C.C. Thoene (IAA-CSIC),
J. Gorosabel (IAA-CSIC, UPV-EHU), N.R. Tanvir (U. Leicester),
J.P.U. Fynbo (DARK/NBI), P. Pesev (GRANTECAN), G. Gomez Velarde
(GRANTECAN), and D. Perez Valladares (GRANTECAN) report on behalf
of a larger collaboration:
Photometric observations of the afterglow of GRB 141220A (Cummings et al.
GCN 17196, Gorosabel et al. GCN 17197, de Ugarte Postigo et al. GCN 17198)
were obtained by OSIRIS/GTC starting 20.6 min after the GRB onset. The
afterglow was detected at r' = 18.11+/-0.05 mag in the first image and had
decayed by 0.6+/-0.1 mag 38.7 min after the burst. Using our photometric data
we derive a decay slope of alpha=0.96+/-0.11 (where F_nu ~ t^-alpha). These
results are consistent with the observations reported by Guidorzi et al. (GCN
17199). Our photometry was performed using SDSS stars as reference.
We encourage further observations and in particular spectroscopy of the
afterglow, in particular to check for possible variability of the FeII* features
between 5400 and 6100 A.
GCN Circular 17199
Subject
GRB 141220A: LT optical afterglow observations
Date
2014-12-20T08:32:50Z (12 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
C. Guidorzi (U. Ferrara), A. Gomboc (U. Ljubljana)
on behalf of a larger collaboration report:
The 2-m Liverpool Telescope automatically began observing Swift
GRB 141220A (Cummings et al. GCN 17196) on Dec 20 at 06:04:57 UT
(125 sec after the burst trigger).
The robotic LT-TRAP pipeline identified the optical afterglow
at the position reported by Gorosabel et al. (GCN 17197)
with r=18.6 +- 0.1 mag at 34 minutes after the GRB,
calibrated against nearby SDSS-R stars.
GCN Circular 17198
Subject
GRB 141220A: Redshift from OSIRIS at the 10.4m GTC
Date
2014-12-20T07:53:28Z (12 years ago)
From
Antonio de Ugarte Postigo at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), C.C. Thoene (IAA-CSIC),
J. Gorosabel (UPV, IAA-CSIC), N. Tanvir (U. Leicester), J.P.U. Fynbo (DARK/NBI),
P. Pesev (GRANTECAN), G. Gomez Velarde (GRANTECAN), and
D. Perez Valladares (GRANTECAN) report on behalf of a larger collaboration
We observed the afterglow of GRB141220A (Cummings et al. GCN 17196, Gorosabel
et al. GCN 17197) with OSIRIS at the 10.4m GTC. Observations began at 6:45 UT
(50 min after the burst). In a first 600 s spectrum obtained with grism R1000B covering
from 3750 to 7800 A we detect absorption features of AlII, FeII, MgII, MgI, at a redshift
of 1.3195, including several absorptions of FeII* which make it very likely the redshift of
the GRB. We also detect two MgII intervening systems at redshifts of 1.280 and 0.527.
GCN Circular 17197
Subject
GRB141220A: 1.23m CAHA I-band observations
Date
2014-12-20T07:52:06Z (12 years ago)
From
Javier Gorosabel at IAA-CSIC <jgu@iaa.es>
J. Gorosabel (IAA-CSIC/UPV-EHU), S. Hellmich (DLR), A. de Ugarte Postigo (IAA-CSIC), S. Mottola (DLR), C. Thoene (IAA-CSIC), report on behalf of a larger collaboration:
We observed the field of GRB 141220A with the 1.23m CAHA in the I-band starting ~8 min post burst. A bright afterglow is detected at RA(J2000)=13:00:15.76, DEC(J2000)=32:08:46:4 (+/-0.8"). We note an important discrepancy with the initial position reported by Swift.
GCN Circular 17196
Subject
GRB 141220A: Swift detection of a burst with an optical afterglow
Date
2014-12-20T06:23:27Z (12 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC),
A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf
of the Swift Team:
At 06:02:52 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 141220A (trigger=621915). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 195.050, +32.144 which is
RA(J2000) = 13h 00m 12s
Dec(J2000) = +32d 08' 37"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a double-peaked
structure with a duration of about 10 sec. The peak count rate
was ~5000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 06:04:31.8 UT, 99.2 seconds after
the BAT trigger. The position determined from promptly downlinked data
differs significantly from the on-board position, suggesting that the
XRT may have centroided on a cosmic ray; the initial XRT position
notice should be treated with caution. Using promptly downlinked data
we find a fading, uncatalogued X-ray source located at RA, Dec
195.06735, 32.13361 which is equivalent to:
RA(J2000) = 13h 00m 16.16s
Dec(J2000) = +32d 08' 01.0"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 64 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.33
x 10^20 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 105 seconds after the BAT trigger. The 2.7'x2.7' sub-image shows a
likely optical afterglow near the XRT position. We are unable to confirm or
measure a magnitude due to the loss of star tracker lock.
We note that the XRT position may have an additional error of order
10 arcseconds due to star tracker lock. A more accurate location
will be generated when the full dataset is available.
Burst Advocate for this burst is J. R. Cummings (jayc 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.)