GRB 211227A
GCN Circular 31316
Subject
GRB 211227A: Swift detection of a burst
Date
2021-12-27T23:48:49Z (3 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
A. P. Beardmore (U Leicester), S. D. Barthelmy (GSFC),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII),
B. Sbarufatti (PSU), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto)
report on behalf of the Neil Gehrels Swift Observatory Team:
At 23:32:06 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 211227A (trigger=1091101). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 132.126, -2.702 which is
RA(J2000) = 08h 48m 30s
Dec(J2000) = -02d 42' 05"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex
structure with a duration of about 100 sec. The peak count rate
was ~5200 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 23:33:20.3 UT, 73.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 132.14898,
-2.73556 which is equivalent to:
RA(J2000) = 08h 48m 35.76s
Dec(J2000) = -02d 44' 08.0"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 146 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
https://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 (2.37 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.3
(+3.24/-2.79) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 6.84e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 81 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' 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
0.020.
Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk).
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/)
GCN Circular 31318
Subject
GRB 211227A: BOOTES-2/TELMA optical upper limit
Date
2021-12-28T01:09:43Z (3 years ago)
From
Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>
Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia, R. Sanchez-Ramirez (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), R. Fernandez-Munoz (IHSM/UMA-CSIC) and M. Jelinek (ASU-CAS), on behalf of a larger collaboration, report:
Following the detection of GRB 211227A by Swift (Beardmore et al. GCNC 31316), the 0.6m BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain) automatically responded to this burst starting on Dec. 27 at 23:32:49 UT (~43 s after trigger). But due to technical problems, only images taken after 23:42 UT (~10 min after trigger) could be used. No new source is detected within the XRT error region in the co-added image (20 x 10 s, clear filter) down to 19.9 mag. This non-detection is consistent with the report from MASTER (Lipunov et al. GCNC 31315) and UVOT (Beardmore et al. GCNC 31316).
We thank the staff at La Mayora for its excellent support.
GCN Circular 31319
Subject
GRB 211227A: MAXI/GSC detection
Date
2021-12-28T01:13:44Z (3 years ago)
From
Motoko Serino at Aoyama Gakuin U. <serino@phys.aoyama.ac.jp>
M. Tominaga (JAXA), Y. Kawakubo (LSU), M. Serino (AGU),
H. Negoro, M. Nakajima, K. Kobayashi, K. Asakura, K. Seino (Nihon U.),
T. Mihara, T. Tamagawa, J. Li, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, K. Komachi, H. Hiramatsu, A. Yoshida (AGU),
Y. Tsuboi, W. Iwakiri, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.),
M. Shidatsu, M. Iwasaki (Ehime U.),
N. Kawai, M. Niwano, R. Hosokawa, Y. Imai, N. Ito, Y. Takamatsu (Tokyo Tech),
S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, T. Nagatsuka, T. Kurihara(JAXA),
Y. Ueda, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake, Y. Goto, R. Uematsu, K. Inaba (Kyoto U.),
H. Tsunemi (Osaka U.), M. Yamauchi, Y. Nonaka, T. Sato, R. Hatsuda, R. Fukuoka (Miyazaki U.),
T. Kawamuro (UDP/NAOJ), K. Yamaoka (Nagoya U.), M. Sugizaki (NAOC)
report on behalf of the MAXI team:
The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient
source at 23:32:06 UT on 2021 December 27.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (132.253 deg, -2.658 deg) = (08 49 00, -02 39 28) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.12 deg and 0.09 deg, respectively.
The roll angle of long axis from the north direction is 66.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 630 +- 48 mCrab
(4.0-10.0keV, 1 sigma error).
We conclude that this event is coincidence with the GRB event reported by Swift
(R.A., Dec) = (132.14898,-2.73556) (J2000) (GCN #31316).
GCN Circular 31320
Subject
GRB 211227A: Nanshan/NEXT optical observations and host galaxy candidate
Date
2021-12-28T02:22:53Z (3 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
S.Y. Fu (NAOC), Z.P. Zhu (NAOC,HUST), X. Liu, S.Q. Jiang, D. Xu (NAOC),
X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 211227A (Beardmore et al. GCN Circ. 31316)
using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China.
Observations automatically started at 23:33:37 UT on 2021-12-27 (i.e.,
90.14 s after the BAT trigger), and a series of 40 s, 60 s, 90 s frames
were obtained in the Sloan r-filter.
Within the Swift/XRT error circle (Beardmore et al. GCN Circ. 31316), no
uncatalogued optical transient is detected in our stacked image down to
a limiting magnitude of r ~ 20.0 mag, calibrated with the nearby
PanSTARRS field.
However, there exists a known source at the border of the Swift/XRT
error circle at coordinates: R.A. (J2000)=08:48:35.975 and Dec (J2000)=
-02:44:06.93, which has r ~ 19.6 mag from Nanshan/NEXT, r ~ 19.40 mag
and classified as galaxy with a photo-redshift of 0.244 +/- 0.0888 from
SDSS, r ~ 19.47 mag from PanSTARRS, as well as r ~ 19.25 from Legacy
Survey. No apparent brightening of the galaxy is seen in comparison of
Nanshan/NEXT and different surveys, indicating that the contribution of
the optical counterpart of the burst is negligible if the galaxy is the
host of the burst.
GCN Circular 31321
Subject
GRB 211227A: LCO Optical Observations
Date
2021-12-28T02:51:59Z (3 years ago)
From
Robert Strausbaugh at U. of the Virgin Islands <robert.strausbaugh@uvi.edu>
R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (College of Marin) report on behalf of a larger collaboration:
We observed Swift GRB 211227A (Beardmore, et al., GCN 31316) with the LCO 1-m Sinistro instrument at the Teide, Tenerife site, on December 28, from 00:39 to 01:11 UT (corresponding to 1.12 to 1.48 hours from the GRB trigger time) with the Bessel R and I filters.
We performed a series of 4x240s exposures in R and I bands. We detect no sources within the Swift XRT detection region (Beardmore, et al., GCN 31316) in either band. The following upper limits are calculated using the USNO-B.1 catalog as reference:
R>22.81
I>22.42
We do note the presence of a faint uncatalogued source just outside the XRT region at RA, DEC = (132.1449185, -2.7343489) at the following magnitudes, calculated with respect to the USNO-B.1 catalog:
R=21.79+/-0.20
I=22.13+/-0.24
We recommend continued monitoring of this source to determine if it is fading. These magnitudes are not corrected for galactic extinction.
R.S. is funded by NSF AST grant #1831682
GCN Circular 31322
Subject
GRB 211227A: Enhanced Swift-XRT position
Date
2021-12-28T03:27:50Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team.
Using 789 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 211227A, 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 = 132.14889, -2.73531 which is equivalent
to:
RA (J2000): 08h 48m 35.73s
Dec (J2000): -02d 44' 07.1"
with an uncertainty of 2.6 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 31323
Subject
GRB 211227A: Liverpool Telescope upper limits
Date
2021-12-28T05:27:43Z (3 years ago)
From
Daniel Perley at Liverpool JMU <d.a.perley@ljmu.ac.uk>
D. A. Perley (LJMU) reports:
We acquired imaging at the position of GRB 211227A (Beardmore et al.,
GCN 31316) using the IO:O camera of the 2m robotic Liverpool Telescope.
The field was observed twice in the griz filters on 2021-12-28 UT, with
the first epoch taking place between 00:36:10 and 00:45:43 and the
second between 02:04:43 and 02:14:18.
No new source is detected within or near the XRT position (Goad et al.,
GCN 31322) after digital subtration of reference imaging from the
Pan-STARRS 1 survey. Photometry with reference to PS1 secondary
standard stars in the field gives the following upper limits:
dt(days) magnitude
0.04449 g > 21.99
0.04625 r > 22.62
0.04799 i > 22.68
0.04974 z > 21.36
The LCO source mentioned by Strausbaugh et al. (GCN 31321) is detected
in PS1 reference imaging and is also marginally detected in both sets of
(unsubtracted) LT images and is far from the enhanced XRT error circle,
suggesting it is unlikely to be related to the GRB.
DisclaimerNone
GCN Circular 31324
Subject
GRB 211227A: A possible short GRB with extended emission at z = 0.228?
Date
2021-12-28T12:22:53Z (3 years ago)
From
Daniele B Malesani at Radboud U <d.malesani@astro.ru.nl>
D. B. Malesani (Radboud Univ. and DAWN/NBI), L. Izzo (DARK/NBI), D. Xu
(NAOC/CAS), A. de Ugarte Postigo (Obs. de la Cote d'Azur), D. A. Kann
(IAA/CSIC), A. J. Levan (Radboud Univ.), Z.P. Zhu (NAOC, HUST), S.Y. Fu
(NAOC), report on behalf of the Stargate collabaration:
We observed the location of GRB 211227A (Beardmore et al., GCN 31316)
using the ESO VLT UT3 (Melipal) equipped with the X-shooter
spectrograph. Short images were secured with the acquisition camera in
the g, r, and z filters. No new object is detected inside the revised
XRT error circle (Goad et al., GCN 31322) down to an AB magnitude r >
24.7 (mean time Dec 28.191 UT).
The galaxy mentioned by Fu et al. (GCN 31320) is well detected in our
image. Its core lies 3.66" away of the center of the XRT circle (2.4"
90% error radius), though its wings extend towards it.
A spectrum of this object was secured, covering the wavelength range
3000-21000 AA, and consisting of 4 exposures of 600 s each. The
observation mid time was 2021 Dec 28.21 UT (5.60 hr after the GRB). We
detect several emission lines, which we interpret as due to [O II],
Hbeta, [O III] 5007, Halpha, [N II], [S II] all at a common redshift z =
0.228. Absorption features due to Ca II 3933/3968 and the Na I D doublet
5890/5896 are also visible at the same redshift. This value is
consistent with the SDSS photometric redshift. The galaxy is fairly
bright, with an absolute magnitude M_r ~ -21.3 (AB) using i = 18.84 (AB)
from SDSS.
We point out the similarity of the gamma-ray light curve of GRB 211227A
(e.g. https://gcn.gsfc.nasa.gov/notices_s/1091101/BA/) with that of GRB
060614 (e.g. Gehrels et al. 2006, Nature, 444, 1044), suggested by some
authors to be a merger event (e.g. Yang et al. 2015, Nat. Comm., 6,
7323). The location of the GRB, slightly offset from a bright, nearby
galaxy, would also be consistent with this interpretation. We raise the
possibility that GRB 211227A is a short GRB with extended emission.
However, a long GRB, either hosted by the z = 0.228 galaxy, or in the
background, remains a viable possibility.
We encourage further observations of this potentially interesting event
at all wavelengths.
We acknowledge excellent support from the ESO observing staff in
Paranal, in particular Israel Blanchard, Robert De Rosa, and Fuyan Bian.
GCN Circular 31326
Subject
GRB 211227A: Swift-BAT refined analysis
Date
2021-12-28T17:01:31Z (3 years ago)
From
Tyler Parsotan at UMBC/GSFC/CRESST II <parsotat@umbc.edu>
A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha
(GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan
(GSFC/UMBC), T. Sakamoto (AGU), M. Stamatikos (OSU) (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 211227A (trigger #1091101)
(Beardmore et al., GCN 31316). The BAT ground-calculated position is RA,
Dec = 132.144, -2.736 deg which is
RA(J2000) = 08h 48m 34.5s
Dec(J2000) = -02d 44' 10.9"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The
partial coding was 41%.
The BAT light curve showed a complex structure with a duration of about 100
sec. T90 (15-350 keV) is 83.79 +- 8.47 sec (estimated error including
systematics).
The time-averaged spectrum from 0.04 to 126.3 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is 1.60
+- 0.05. The fluence in the 15-150 keV band is 8.0 +- 0.2 x 10^-06
erg/cm2. The 1-sec peak photon flux measured from T+0.06 sec in the 15-150
keV band is 5.1 +- 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/1091101/BA/
GCN Circular 31327
Subject
GRB 211227A: Swift-XRT refined Analysis
Date
2021-12-28T18:27:37Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), A. D'Ai
(INAF-IASFPA), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), B.
Sbarufatti (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester) and A.P. Beardmore report on behalf of the Swift-XRT team:
We have analysed 8.1 ks of XRT data for GRB 211227A (Beardmore et al.
GCN Circ. 31316), from 63 s to 57.9 ks after the BAT trigger. The data
comprise 182 s in Windowed Timing (WT) mode (the first 9 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Goad et al.
(GCN Circ. 31322).
The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=1.27 (+0.21, -0.20). At T+105 s the decay
steepens to an alpha of 2.27 (+0.20, -0.17) before breaking again at
T+220 s to a final decay with index alpha=5.49 (+0.37, -0.30).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.11 (+/-0.07). The
best-fitting absorption column is 2.2 (+0.5, -0.4) x 10^21 cm^-2, in
excess of the Galactic value of 2.4 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 6.1 x 10^-11 (6.6 x 10^-11) erg
cm^-2 count^-1.
A summary of the WT-mode spectrum is thus:
Total column: 2.2 (+0.5, -0.4) x 10^21 cm^-2
Galactic foreground: 2.4 x 10^20 cm^-2
Excess significance: 7.8 sigma
Photon index: 1.11 (+/-0.07)
If the light curve continues to decay with a power-law decay index of
5.49, the count rate at T+24 hours will be 7.3 x 10^-14 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.5 x
10^-24 (4.9 x 10^-24) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01091101.
This circular is an official product of the Swift-XRT team.
GCN Circular 31328
Subject
GRB 211227A: Swift/UVOT Upper Limits
Date
2021-12-28T19:38:09Z (3 years ago)
From
Alexander Belles at PSU/Swift <aub1461@psu.edu>
A. Belles (PSU) and A. P. Beardmore (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 211227A
82 s after the BAT trigger (Beardmore et al., GCN Circ. 31316).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 31322)
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 first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 82 232 147 >19.4
u_FC 294 544 246 >19.2
white 82 1021 334 >19.5
v 624 4923 241 >18.7
b 550 742 39 >18.6
u 294 5431 357 >19.4
w1 673 5333 235 >19.7
m2 648 5127 235 >20.4
w2 772 792 19 >19.0
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.020 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 31333
Subject
GRB 211227A: CALET Gamma-Ray Burst Monitor detection
Date
2021-12-29T08:03:36Z (3 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
M. L. Cherry (LSU),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The long GRB 211227A (Swift detection and refined analysis:
Beardmore et al., GCN Circ. 31316, Lien et al., GCN Circ. 31326;
MAXI/GSC detection: Tominaga et al., GCN Circ. 31319;
https://gcn.gsfc.nasa.gov/other/211227A.gcn3) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 23:32:07.476 UTC on 27 December 2021.
The burst signal was seen by all CGBM detectors.
Because of a problem in one of the ground alert processing script, the GCN
notice was not distributed automatically for this event.
The burst light curve shows a multi-peaked structure which starts
at T-0.6 sec and ends at T+77.2 sec.
The T90 and T50 durations measured by the SGM data are 64.5 +- 10.3 sec and
22.0 +- 2.0 sec (40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1324683113/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.
GCN Circular 31341
Subject
GRB 211227A: Deep early CAHA 2.2m/CAFOS observation
Date
2021-12-30T11:25:54Z (3 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (Obs. Cote d'Azur), C.
C. Thoene, M. Blazek (both HETH), J. F. Agui Fernandez (HETH/IAA-CSIC),
and S. Gongora (CAHA) report:
We observed the localization of GRB 211227A (Swift detection: Beardmore
et al., GCN #31316; Enhanced XRT position: Goad et al., GCN #31322;
MAXI/GSC Detection: Tominaga et al., GCN #31319) with CAFOS, mounted on
the 2.2 m telescope, at the Calar Alto Observatory (Almeria, Spain). The
observation started at 00:08:45 UT on 28 December 2021 (36.65 min after
the GRB) and consisted of 30 x 90 s integrations in the i' band.
Observing conditions were mediocre (wind, some clouds, 3" seeing).
Our combined image is centered at 0.04233 d after the trigger. No
afterglow is detected in the XRT error circle, in agreement with other
observations (Lipunov et al., GCN #31315; Hu et al., GCN #31318; Fu et
al., GCN #31320; Strausbaugh et al., GCN #31321; Perley, GCN #31323;
Malesani et al., GCN #31324; Belles et al., GCN #31328). This area is
affected by the outer PSF wing of a bright nearby star, causing a
variable background. Using an isolated SDSS star, we measure a limit
away from the stellar PSF of i' > 23.4 mag, but caution this limit will
be somewhat less deep in the XRT error circle.
Assuming the GRB is associated with the nearby galaxy at redshift z =
0.228 (Malesani et al., GCN #31324), a comparison with the light curve
of GRB 060614 (Kann et al. 2011, ApJ, 734, 96) reveals this limit is
about 3 magnitudes fainter than the equivalent afterglow magnitude for
GRB 060614 at the same redshift.
GCN Circular 31376
Subject
GRB 211227A: Gemini South Optical Observations
Date
2022-01-03T18:44:12Z (3 years ago)
From
Brendan O'Connor at UMD <oconnorb@umd.edu>
B. O'Connor (GWU, UMD), E. Troja (NASA-GSFC), A. Gottlieb (UMD, NASA-GSFC)
report on behalf of a larger collaboration:
We observed the field of GRB 211227A (Beardmore et al., GCN #31316)
with Gemini/GMOS-S on December 30, 2021 starting at 05:36:43 UT
(corresponding to ~2.3 d post-trigger). The observations were performed
in i-band with a total exposure of 15x120 s at airmass 1.2 with good
weather conditions and seeing ~0.7".
Within the XRT enhanced position (Goad et al., GCN #31322), we do not
detect any source to depth i>26 AB mag. This is consistent with
other non-detections currently reported (Lipunov et al., GCN #31315;
Hu et al., GCN #31318; Fu et al., GCN #31320; Strausbaugh et al.,
GCN #31321; Perley, GCN #31323; Malesani et al., GCN #31324;
Belles et al., GCN #31328, Kann et al., GCN #31341).
Due to the potentially nearby distance (z=0.228; Malesani et al.,
GCN #31324), these observations disfavor a GRB-supernova similar
to SN1998bw. In terms of probing potential kilonova emission,
this limit would have detected an AT2017gfo-like event at z=0.228.
We thank the staff of the Gemini Observatory, in particular Janice
Lee and Venu Kalari, for rapid scheduling of these observations.
GCN Circular 31386
Subject
GRB 211227A: Lijiang 2.4m Telescope Optical Observations
Date
2022-01-04T15:35:42Z (3 years ago)
From
Liping Xin at NAOC, SVOM <xlp@nao.cas.cn>
Enwei Liang (GXU), Tingfeng Yi(YNNU), Liping Xin (NAOC),
Haicheng Feng (YNAO CAS), Houjun Lv (GXU), Xianggao Wang (GXU)
and Youdong Hu (IAA) report:
We observed the field of GRB 211227A (Beardmore et al., GCN #31316)
with the Lijiang 2.4m telescope on January 3, 2022���starting at 18:23:25 UT���
about 6.8 day after trigger. The observations were performed in R band
with a total exposure of 1200 s at airmass of 1.2 and a seeing of ~1.7,
under good weather conditions.
Within the XRT enhanced errorbox (Goad et al., GCN #31322), we did not
detect any source to a depth of R > 21.5 mag calibrated by nearby
SDSS DR12 stars (SDSS J084838.92-024405.9���J084838.22-024355.7���
J084836.33-024403.8). This is consistent with other non-detections
reported (Lipunov et al., GCN #31315; Hu et al., GCN #31318;
Fu et al., GCN #31320; Strausbaugh et al.,GCN #31321; Perley, GCN #31323;
Malesani et al., GCN #31324; Belles et al., GCN #31328,
Kann et al., GCN #31341,GCN #31376 O'Connor et al.).
We thank the staff of the Lijiang 2.4m telescope,
in particular Jiangguo Wang for scheduling of these observations.
GCN Circular 31544
Subject
GRB 211227A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
Date
2022-02-03T10:32:43Z (3 years ago)
From
Anastasia Tsvetkova at Ioffe Institute <tsvetkova@mail.ioffe.ru>
A. Tsvetkova, D. Frederiks, A.Lysenko, D. Svinkin,
A. Ridnaia, M. Ulanov (all Ioffe), and A.Y. Lien (U Tampa), report:
The long GRB 211227A (Swift-BAT detection:
Beardmore et al., GCN 31316; Lien et al., GCN 31326;
MAXI/GSC detection: Tominaga et al., GCN 31319;
CALET-GRBM detection: Cherry et al., GCN 31333),
T0 (BAT) = 23:32:06.867, was detected by Konus-Wind (KW)
in the waiting mode.
A Bayesian block analysis of the KW waiting mode data in 25-400 keV range
reveals two episodes with count rate excess >10 sigma over background.
The first one, lasting from ~T0-50 s to ~T0-10 s, is due to the solar
activity and is not associated with the GRB.
The second episode, from ~T0-1.5 s to ~T0+81 s, is consistent in time
with the BAT detection. It has a double-peaked structure,
with the first, narrow pulse peaking at ~T0, and the second,
more broad pulse - at ~T0 + 11 s.
To derive broad-band spectral parameters of this burst,
we performed a joint spectral analysis of the Swift/BAT data (15-150 keV)
and the KW 3-channel spectral data (25-1700 keV).
A fit to the time-averaged spectrum, measured from T0-1.540 s�� to
T0+83.836 s,
by the Band GRB function gives alpha = -1.34 (-0.08,+0.10),
beta = -2.26 (-1.11,+0.24), and Ep = 192 (-42,+45) keV; chi^2 = 48.5/ 57
dof.
A fit to the spectrum near the peak KW count rate, measured from
T0+10.236 s to T0+19.068 s,
by the Band function gives alpha = -1.09 (-0.07,+0.08), beta = -2.29
(-0.11,+0.28),
and Ep = 374 (-70,+66) keV; chi^2 = 47.1/58 dof.
The spectrum of the short initial pulse, measured from T0-1.540 s to
T0+4.348 s,
is well fit by a power law with an exponential cutoff (CPL), with
alpha = -1.56 (-0.06,+0.15) and Ep = 366 (-179,+1201) keV; chi^2 =
49.3/59 dof.
Although the Band model fit to this spectrum is not constrained,
fixing beta to the value -2.26, obtained for the time-integrated spectrum,
gives alpha = -1.49 (-0.18, +0.24) and Ep = 240 (-116, +759) keV; chi^2
= 49.0/59 dof.
In the 15-1500 keV band, the total burst fluence is
2.60(-0.21,+0.21)x10^-5 erg/cm^2,
and the 64 ms peak energy flux is 2.0(-0.4,+0.4)x10^-6 erg/cm^2/s.
Assuming the redshift z=0.228 (Malesani et al., GCN 31324)
of the host galaxy candidate (Fu et al., GCN 31320),
and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the isotropic energy release E_iso to 4.9(-0.4,+0,4)x10^51 erg,
the isotropic luminosity L_iso to 4.7(-1.0,+1,0)x10^50 erg/s,
and the rest-frame peak energies of the time-integrated and peak spectra
to 235(-51,+56) keV and 460 (-86, +81) keV, correspondingly.
With these values, GRB 211227A is consistent with the 90% prediction
bands for the 'Amati'
relation and is an outlier in the 'Yonetoku' relation for the sample of��
>300 long KW GRBs
with known redshifts (Tsvetkova et al., 2021, ApJ, 908, 83).
However, if we assume a higher burst redshift (z>0.5), GRB 211227A is
consistent
with both 'Amati' and 'Yonetoku' relations,
see http://www.ioffe.ru/LEA/GRBs/GRB211227A/GRB211227A_rest_frame.pdf
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.
The KW light curve of this burst is available at
http://www.ioffe.ru/LEA/GRBs/GRB211227A/