GRB 141225A
GCN Circular 17652
Subject
GRB 141225A: GMG observation limit
Date
2015-03-29T09:33:06Z (11 years ago)
From
Jirong Mao at Yunnan Obs <jirongmao_obs@ynao.ac.cn>
J. Mao, Y. X. Xin and J.-M. Bai (YNAO) report:
We observed the field of GRB 141225A (D'Avanzo et al., GCN 17229) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG)
station of Yunnan Observatory. Observations began from UT 15:38:35.4 26th, Dec., 2014 (about 16.6 hours after the trigger).
We did not detect the optical counterpart down to a limit of r'~24.3.
J. Mao apologizes for this very later GCN circular submission.
GCN Circular 17248
Subject
Christmas GRB 141225A: GROND Observations
Date
2014-12-29T16:59:03Z (11 years ago)
From
Alexander Kann at TLS Tautenburg <kann@tls-tautenburg.de>
D. A. Kann (TLS Tautenburg), P. Schady, and J. Greiner (both MPE Garching)
report on behalf of the GROND team:
We observed the field of GRB 141225A (Swift trigger 622476; D'Avanzo et
al., GCN #17229) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla
Observatory (Chile).
Observations started at 05:58 UT on 26 December 2014, around 7 hours after
the GRB trigger. They were performed at an average seeing of 1".4 and at
an average airmass of 2.3.
Based on images with exposure times of 2640 s in g'r'i'z' and 2400 s in
JHK, we detect the afterglow (Gorosabel et al., GCN #17230, Guidorzi et
al., GCN #17231) at the following AB magnitudes:
g' = 22.56 +/- 0.07 mag,
r' = 22.31 +/- 0.07 mag,
i' = 22.34 +/- 0.14 mag,
z' = 21.74 +/- 0.12 mag,
J > 21.5 mag,
H > 21.0 mag, and
K > 17.3 mag.
The colors do not point to a strongly extinguished afterglow, implying it
is intrinsically faint.
The given magnitudes and limits are derived based on calibrating the
images against SDSS (g'r'i'z') and 2MASS field stars (JHK) and are not
corrected for the Galactic foreground extinction corresponding to a
reddening of E_(B-V)= 0.017 in the direction of the burst (Schlegel et al.
1998).
GCN Circular 17245
Subject
GRB 141225A: MASTER-SAAO OT light curve
Date
2014-12-28T12:16:57Z (11 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
D.Buckley, S. Potter, A. Kniazev, M. Kotze
South African Astronomical Observatory
E. Gorbovskoy,V. Lipunov, N.Tyurina, P.Balanutsa, D.Denisenko,
M.Pruzhinskaya, A.Kuznetsov, V.Kornilov, D.Kuvshinov,
Lomonosov Moscow State University, Sternberg Astronomical Institute
O.Gres, K.Ivanov, S.Yazev, N.M.Budnev, V.A.Poleshchuk
Irkutsk State University
V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinsky, I.Zalozhnih, A. Popov
Ural Federal University, Kourovka
H. Levato and C. Saffe
Instituto de Ciencias Astronomicas de la Tierra y del Espacio (ICATE),
San Juan, Argentina
C. Mallamacci, C. Lopez and F. Podest
Observatorio Astronomico Felix Aguilar (OAFA), San Juan National University,
Argentina
MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru)
installed several days ago in South African Astronomical
Observatory (Sutherland) was automatically pointed
to the Swift and Fermi GRB 141225A (Avanzo et. al. GCN 17229).
Firstly MASTER-SAAO pointed by FERMI coordinates and made first exposure 28
sec after FERMI trigger at 2014-12-25 23:02:28 UT (Buckley et al.,
17233).
Then MASTER-SAAO pointed to the Swift coordinates 20 sec after Swift notice
time and 113 sec after trigger time at 2014-12-25 23:03:00 UT.
The results of our photometery are:
Start T-T_mid Exp. Mag Coadd
UT s s unf ?
23:03:00 123 20 17.1 no
23:03:34 161 30 17.3 no
23:04:15 207 40 17.5 no
23:05:05 263 50 17.7 no
23:06:06 329 60 18.9 no
23:07:17 405 70 18.7 no
23:08:38 556 200 19.0 2
23:12:19 823 290 19.8 2
23:17:31 3161 3600 21.3 20
Our band is well described by a parity 0.8R+0.2B (USNO B1).
The light curve from 113 to 300 power low index is about
alpha ~= 0.76+-0.10 (F ~ t_-alpha)
and alpha =~ 1.51 from 400 to 1500 .
We see ~1 magnitude depression at 329 sec.
The magnitudes in the table are not corrected for the Galactic extinction
because its less than the our errors (Schlegel et al. 1998).
The light curve is available at
http://master.sai.msu.ru/static/GRB/GRB141225A.png
This message may be cited.
GCN Circular 17244
Subject
GRB 141225A: MITSuME Okayama upper limits
Date
2014-12-27T04:27:31Z (11 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 141225A (D'Avanzo et al., GCNC 17229)
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 2014-12-26 18:53:27 UT (~19.9 h after the burst).
We could not detect the previously reported afterglow (Gorosabel et al., GCNC
17230; Guidorzi et al., GCNC 17231) in all the three bands.
Three sigma upper limits of the OT are listed below.
We used SDSS-DR8 catalog for flux calibration.
#T0+[day] MID-UT T-EXP[sec] g' Rc Ic
-----------------------------------------------------
0.68285 15:24:25 3780.0 >19.7 >19.6 >19.0
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
GCN Circular 17243
Subject
GRB 141225A: TAROT Calern observatory optical observations
Date
2014-12-27T00:45:35Z (11 years ago)
From
Alain Klotz at IRAP-CNRS-OMP <Alain.Klotz@free.fr>
Klotz A. (IRAP-CNRS-OMP), Gendre B. (IRAP-CNRS-OMP),
Boer M., Siellez K., Dereli H., Bardho O. (UNS-CNRS-OCA),
Atteia J.L. (IRAP-CNRS-OMP) report:
We imaged the field of GRB 141225A detected by SWIFT
(trigger 513505) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.
The observations started 8.2 min after the GRB trigger.
The elevation of the field increased from
50 degrees above horizon and weather conditions
were good.
We co-added a series of exposures to measure the optical
afterglow discovered by Gorosabel et al. (GCNC 17230):
Tstart Tend
(sec) (sec) Rmag +/-
496 907 18.8 0.3
918 1315 19.0 0.3
1327 1728 19.9 0.5
The afterglow is no longer detected in the next images.
Magnitudes were estimated using USNO-B1 star USNO-B1 1237-0186662
(R.A.=138.789, Dec=+33.797) as Sonbas et al. (GCNC 17240).
Magnitudes are not corrected for galactic dust extinction.
GCN Circular 17242
Subject
GRB 141225A: Swift/UVOT refined analysis
Date
2014-12-26T18:37:57Z (11 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and P. D'Avanzo (INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 141225A
428 s after the BAT trigger (D'Avanzo et al., GCN Circ. 17229). The optical
afterglow has been reported (Gorosabel et al, GCN Circ. 17230; Guidorzi et
al.,
GCN Circ. 17231; Malesani et al., GCN Circ. 17232; Kuin & D'Avanzo,
GCN.Circ.
17233; Xu et al., GCN Circ. 17236; Buckley et al., 17237; Sonbas et al.,
GCB
Circ. 17240) with a redshift of z=0.915 (Gorosabel et al., GCN Circ. 17234).
Preliminary detections and 3-sigma upper limits 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 428 578 147 18.81 +/- 0.06
white 858 1008 147 19.76 +/- 0.10
v 735 1406 78 >19.2
b 660 1495 86 >19.5
u 636 1481 97 19.19 +/- 0.19
w1 611 1456 97 >19.0
m2 760 780 19 >18.6
w2 6480 6680 197 >19.7
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 17241
Subject
GRB 141225A: Fermi GBM detection
Date
2014-12-26T17:48:26Z (11 years ago)
From
Peter Jenke at MSFC <peter.a.jenke@nasa.gov>
P. Jenke (UAH) reports on behalf of the Fermi GBM Team:
"At 23:01:13.82 UT on December 25 2014, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 141225A (trigger 441241276/141225959),
which was also detected by
Swift (P. D'Avanzo et al. 2014, GCN 17229). Additionally,
there were optical detections from the 1.23m CAHA telescope
(J. Gorosabel et al. 2014 GCN 17230) among others as well
as a redshift measurement (J. Gorosabel et al. 2014 GCN 17234).
The GBM on-ground location, using the Fermi GBM trigger
data, is consistent with the Swift/XRT and optical locations.
The angle of the burst direction to the Fermi LAT boresight
is 104 degrees.
The GBM light curve consists of one FRED-like peak with a
duration (T90) of about 56 s (50-300 keV).
The time-averaged spectrum from T0-4.1s to T0+21.5s
is well fit by a Band function with Epeak = 187 +/- 29 keV,
Alpha = -0.35 +/- 0.17 and Beta = -2.0 +/- 0.1.
The event fluence (10-1000 keV) in this time interval is
(6.5 +/- 0.3)E-06 ergs/cm^2. The 1.0-sec peak photon flux measured
starting from T0+9.7s in the 10-1000 keV band
is 2.5 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 17240
Subject
GRB 141225A: very early T60 observations
Date
2014-12-26T16:15:01Z (11 years ago)
From
Eda Sonbas at NASA/GSFC <edasonbas@gmail.com>
E. Sonbas (Adiyaman Univ.), T. Guver (Istanbul Univ.), E. Gogus (Sabanci
Univ.), M. Parmaksizoglu, M. Dindar, H. Kirbiyik (TUG) report on behalf of
a larger collaboration
We observed the field of Swift GRB 141225A (D'Avanzo et al., GCN#17229)
with the 0.60 meter robotic T60 telescope (Dindar et al. 2014; Bakirlitepe,
TUBITAK National Observatory, Turkey), starting December, 25, 23:03:16.37
UT (~ 129 second after the trigger). Observations were carried out with the
R and B filters. The afterglow (Gorosabel et al., GCN 17230; Guidorzi et
al., GCN 17231; Malesani et al., GCN 17232; Kuin & D'Avanzo, GCN 17233, Xu
et al. GCN 17236, Buckley et al. GCN 17237) is clearly detected in the R
band images with an exposure time of 60 s.
Using USNO-B1 star USNO-B1 1237-0186662 (R.A.=138.789, Dec=+33.797) in the
field, the R magnitudes of the OT were estimated as follows;
t-t0 (sec) exp.(s) filt mag err (+/-)
~129 60 R 17.04 0.04
~195 60 R 17.15 0.02
Further analysis are ongoing.
We are grateful to TUBITAK National Observatory for a partial support in
using T60 telescope with project number 539 and technical support.
GCN Circular 17239
Subject
GRB 141225A: Swift-BAT refined analysis
Date
2014-12-26T14:29:58Z (11 years ago)
From
Hans Krimm at NASA-GSFC <hans.a.krimm@nasa.gov>
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), P. D'Avanzo (INAF-OAB), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 141225A (trigger #622476)
(D'Avanzo, et al., GCN Circ. 17229). The BAT ground-calculated position is
RA, Dec = 138.754, 33.774 deg which is
RA(J2000) = 09h 15m 01.1s
Dec(J2000) = +33d 46' 27.7"
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 26%.
The burst location first entered the BAT field of view at ~T-40 sec, during a
pre-planned slew. The mask-weighted light curve shows a single FRED-shaped
peak, beginning at T+5 sec, peaking at T+12 sec and returning to baseline level
by T+50 sec. T90 (15-350 keV) is 40.24 +- 7.04 sec sec (estimated error
including systematics).
The time-averaged spectrum from T+5.50 to T+50.68 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.32 +- 0.15. The fluence in the 15-150 keV band is 2.5 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+11.76 sec in the 15-150 keV band is
1.3 +- 0.4 ph/cm2/sec. 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/622476/BA/
GCN Circular 17238
Subject
GRB 141225A: Swift-XRT refined Analysis
Date
2014-12-26T14:28:04Z (11 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), J.A. Kennea
(PSU), V. Mangano (PSU), M.C. Stroh (PSU), K.L. Page (U. Leicester), C.
Pagani (U. Leicester), A.P. Beardmore (U. Leicester) and P. D'Avanzo
report on behalf of the Swift-XRT team:
We have analysed 8.0 ks of XRT data for GRB 141225A (D'Avanzo et al.
GCN Circ. 17229), from 434 s to 40.8 ks after the BAT trigger. The
data comprise 33 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Evans et al. (GCN Circ. 17235).
The light curve can be modelled with an initial power-law decay with an
index of alpha=2.22 (+0.32, -0.25), followed by a break at T+1770 s to
an alpha of 1.12 (+0.26, -0.38).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.67 (+0.13, -0.12). The
best-fitting absorption column is consistent with the Galactic value
of 1.5 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 3.9 x 10^-11 (4.0 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.5 (+/-2.1) x 10^20 cm^-2
Galactic foreground: 1.5 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.67 (+0.13, -0.12)
If the light curve continues to decay with a power-law decay index of
1.12, the count rate at T+24 hours will be 1.9 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.3 x
10^-14 (7.4 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00622476.
This circular is an official product of the Swift-XRT team.
GCN Circular 17237
Subject
GRB 141225A: MASTER-SAAO first OT detection
Date
2014-12-26T10:41:39Z (11 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
D.Buckley, S. Potter, A. Kniazev, M. Kotze
South African Astronomical Observatory
E. Gorbovskoy,V. Lipunov, N.Tyurina P.Balanutsa, D.Denisenko,
M.Pruzhinskaya,A.Kuznetsov, V.Kornilov, D.Kuvshinov,
Lomonosov Moscow State University,
Sternberg Astronomical Institute
O.Gres, K.Ivanov, S.Yazev, N.M.Budnev, V.A.Poleshchuk
Irkutsk State University
V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinsky, I.Zalozhnih, A. Popov
Ural Federal University, Kourovka
H. Levato and C. Saffe
Instituto de Ciencias Astronomicas de la Tierra y del Espacio (ICATE),
San Juan, Argentina
C. Mallamacci, C. Lopez and F. Podest
Observatorio Astronomico Felix Aguilar (OAFA), San Juan National University,
Argentina
MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru)
installed several days ago in South African Astronomical
Observatory (Sutherland) was automatically pointed
to the Swift and Fermi GRB 141225A (Avanzo et. al. GCN 17229).
Firstly MASTER-SAAO pointed by FERMI coordinates and made first exposure
28 sec. after FERMI trigger at 2014-12-25 23:02:28 UT.
Then MASTER-SAAO pointed to the Swift coordinates 20 sec after Swift
notice time and 113 sec after trigger time at 2014-12-25 23:03:00 UT in
two polarizations.
MASTER-SAAO discovered OT source (Gorosabel et. al. 17230, Malesani et. al
17232, Kuin et. al 17233, Xu et. al 17236):
Ra: 09:15:06.94
Dec: +33:47:30.87
Mag: 17.5
The source is visible on the subsequent frames. The data reduction is
continued.
Our band is well described by a parity 0.8R+0.2B (USNO B1).
This message may be cited.
GCN Circular 17236
Subject
GRB 141225A: Nanshan very early optical observations
Date
2014-12-26T06:39:37Z (11 years ago)
From
Dong Xu at DARK/NBI <dong.dark@gmail.com>
D. Xu (DARK, NAOC) and X. Gao (Urumqi No.1 Senior High School, Xinjiang) report:
We observed the field of GRB 141225A (D'Avanzo et al., GCN 17229)
using the 36cm robotic telescope located at Nanshan, Xinjiang, China.
Observations started at 23:04:14 UT on 2014-12-25, i.e., 187 s after
the burst, and subsequently 3x40s, 4x60s, and 12x90s unfiltered images
were obtained.
The optical afterglow (Gorosabel et al., GCN 17230; Guidorzi et al.,
GCN 17231; Malesani et al., GCN 17232; Kuin & D'Avanzo, GCN 17233) is
detected in all 40s and 60s exposures and only in the beginnings of
90s exposures, and is evident of decaying. The afterglow has m(R)~17.2
from the first 40s image (i.e., 187 s - 227 s post-burst), calibrated
with R-band magnitudes of nearby SDSS stars.
GCN Circular 17235
Subject
GRB 141225A: Enhanced Swift-XRT position
Date
2014-12-26T04:07:30Z (11 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 1893 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 141225A, 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 = 138.77827, +33.79184 which is equivalent
to:
RA (J2000): 09h 15m 6.79s
Dec (J2000): +33d 47' 30.6"
with an uncertainty of 1.6 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 17234
Subject
GRB 141225A: Redshift from OSIRIS at the 10.4m GTC
Date
2014-12-26T03:08:38Z (11 years ago)
From
Javier Gorosabel at IAA-CSIC <jgu@iaa.es>
J. Gorosabel (UPV-EHU, IAA-CSIC), A. de Ugarte Postigo (IAA-CSIC,
DARK/NBI), C.C. Thoene (IAA-CSIC), N. Tanvir (U. Leicester), J.P.U. Fynbo
(DARK/NBI), D. Garc�a-Alvare (GTC), "A. Perez-Romero (GTC)
report on behalf of a larger collaboration:
We observed the afterglow of GRB 141225A (D'Avanzo et al. GCN 17229) with
OSIRIS at the 10.4m GTC. Observations began at 00:25:25 UT (~1.4 hours
post burst). Four 600s spectra were taken with the R1000B grism going from
3750 to 7800 AA. A first analisys based on archival arc lamps reveals
absorption features of FeII and MgII at a preliminary redshift of z=0.915.
[GCN OPS NOTE(27dec14): Pera author's request, D.G was changed to D.G-A
and A.P-R was added.]
GCN Circular 17233
Subject
GRB 141225A: UVOT detection
Date
2014-12-26T02:16:13Z (11 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N.P.M. Kuin (MSSL/UCL) and P. D'Avanzo (INAF-OAB) report on behalf of the
Swift Team
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 427 seconds after the BAT trigger. There is a candidate afterglow
in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 09:15:06.92 = 138.77885
DEC(J2000) = +33:47:30.9 = 33.79191
with a 90%-confidence error radius of about 0.66 arc sec. This position is
2.3
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.66 with a 1-sigma error of about 0.08.
A second exposure of 150 seconds in the White filter starting 858 seconds
after
the BAT trigger has an estimated magnitude of 19.61 with a 1-sigma error of
about 0.16, showing a clear decay. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.02.
GCN Circular 17232
Subject
GRB 141225A: Optical aftergow confirmation
Date
2014-12-26T00:05:51Z (11 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
D. Malesani (DARK/NBI), T. Augusteijn (NOT), and P. Jakobsson (Univ.
Iceland) report on behalf of a larger collaboration:
We observed the field of GRB 141225A (D'Avanzo et al., GCN 17229) with
the Nordic Optical telescope equipped with the MOSCA camera.
Observations started at 23:25:08 UT (0.40 hr after the GRB trigger) and
were conducted in the SDSS r band.
Consistent with the XRT position (see
http://www.swift.ac.uk/xrt_positions/), we detect a bright source not
present in the DSS, which is likely the optical afterglow of GRB
141225A. Its coordinates are (J2000):
RA = 09:15:06.89
Dec = +33:47:30.8
and an approximate magnitude of R ~ 19.5 (Vega; assuming R = 16.2 for
the USNO star at RA = 09:15:09.46, Dec = +33:47:48.7).
This is the same source reported by Gorosabel et al. (GCN 17230) and
Guidorzi et al. (GCN 17231).
GCN Circular 17231
Subject
GRB 141225A: LT optical candidate
Date
2014-12-25T23:58:02Z (11 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
C. Guidorzi (U. Ferrara), J. Japelj (U. Ljubljana),
A. Melandri (INAF-OAB) on behalf of a large
collaboration reports:
The 2-m Liverpool Telescope automatically began
observing Swift GRB 141225A (D'Avanzo et al. GCN 17229).
Within the XRT error circle we found an uncatalogued
object at the following position:
RA(J2000) = 09:15:06.92
Dec(J2000)= +33:47:30.6
with r=20.3 +- 0.1 mag at 36 minutes post trigger,
calibrated against SDSS nearby stars.
GCN Circular 17230
Subject
GRB 141225A: 1.23m CAHA optical observations
Date
2014-12-25T23:52:18Z (11 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 141225A (D'Avanzo et al. GCN 17229) with the
1.23m CAHA telescope in the I-band starting at 23:07:27.7 UT (starting
~6.5 min post burst). We detected an optical source located at
RA(J2000)=09:15:06.93, DEC(J2000)=33:47:30.8 (+/-1") with a very
estimative magnitude of I~18.5 (Vega) consistent with the XRT position."
GCN Circular 17229
Subject
GRB 141225A: Swift detection of a burst
Date
2014-12-25T23:28:25Z (11 years ago)
From
Hans Krimm at NASA-GSFC <hans.krimm@nasa.gov>
P. D'Avanzo (INAF-OAB), A. P. Beardmore (U Leicester),
M. G. Bernardini (INAF-OAB), J. R. Cummings (NASA/UMBC),
N. Gehrels (NASA/GSFC), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), A. Y. Lien (GSFC/UMBC),
A. Melandri (INAF-OAB), C. J. Mountford (U Leicester) and
J. L. Racusin (NASA/GSFC) report on behalf of the Swift Team:
At 23:01:07 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 141225A (trigger=622476). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 138.751, +33.795 which is
RA(J2000) = 09h 15m 00s
Dec(J2000) = +33d 47' 41"
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 30 sec. The peak count rate
was ~1600 counts/sec (15-350 keV), at ~6 sec after the trigger.
The XRT began observing the field at 23:08:10.5 UT, 423.5 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 138.7782, 33.7919 which
is equivalent to:
RA(J2000) = 09h 15m 06.77s
Dec(J2000) = +33d 47' 30.7"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 82 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 in excess of the Galactic value (1.48 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 1.6
(+1.62/-1.47) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White
filter starting 440 seconds after the BAT trigger. No credible
afterglow candidate has been found in the initial data products. The
8'x 8' region for the list of sources generated on-board covers 100% of
the XRT error circle. The list of sources is typically complete to
about 18 mag. No correction has been made for the expected extinction
corresponding to E(B-V) of 0.02.
Merry Christmas from the Swift Team!
Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT brera.inaf.it).
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.)