GRB 210104B
GCN Circular 29243
Subject
GRB 210104B: Swift detection of a burst
Date
2021-01-04T21:24:45Z (4 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
S. Laha (GSFC/UMBC/CRESST), M. G. Bernardini (INAF-OAB),
A. A. Breeveld (UCL-MSSL), P. D'Avanzo (INAF-OAB), C. Gronwall (PSU),
J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
A. Melandri (INAF-OAB), M. J. Moss (GWU), K. L. Page (U Leicester),
D. M. Palmer (LANL), T. Sbarrato (INAF-OAB) and M. H. Siegel (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:
At 21:10:10 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210104B (trigger=1015919). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 53.601, +37.931 which is
RA(J2000) = 03h 34m 24s
Dec(J2000) = +37d 55' 51"
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 30 sec. The peak count rate
was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 21:11:31.2 UT, 80.5 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 53.5539, 37.9302 which
is equivalent to:
RA(J2000) = 03h 34m 12.93s
Dec(J2000) = +37d 55' 48.7"
with an uncertainty of 2.5 arcseconds (radius, 90% containment). This
location is 133 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. We cannot determine whether the source
is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.67 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 1.6
(+1.04/-0.80) x 10^22 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 83 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 none of
the XRT error circle. 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 0.79.
Burst Advocate for this burst is S. Laha (sib.laha AT gmail.com).
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 29249
Subject
GRB 210104B: BOOTES network optical upper limit
Date
2021-01-04T23:20:22Z (4 years ago)
From
Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>
Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco, A. Reina (Univ. de Malaga), F. Rendon (IAA-CSIC and INTA-CEDEA) R. Fernandez-Munoz (IHSM/UMA-CSIC) and M. Jelinek (ASU-CAS) on behalf of a larger collaboration, report:
Following the Swift trigger of GRB 210104B (Laha et al., GCNC 29243), the 0.3m BOOTES-1B robotic telescope in Mazagon (Huelva), southern Spain, automatically responded to this burst. Series images were taken started 2021-01-04 21:11:00 UT (~50 s after trigger). In the co-added of 10x10 s images, no source is detected within the XRT position (Laha et al., GCNC 29243) which down to 18.1 mag (clear filter).
The 0.6m BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain) also automatically responded to the Swift trigger of GRB 210104B (Laha et al., GCNC 29243). A series of images were taken starting on 2021-01-04 21:11:24 UT (~74 s after trigger). No optical source is detected within the XRT position on the co-added image (10x10 s, clear filter) which down to 19.9 mag.
Those non-detections are consistent with the reports from Swift (Laha et al., GCNC 29243) and MASTER-Net (Lipunov et al., GCNC 29242). Additional observations are ongoing. We thank the staff at INTA-CEDEA and La Mayora for their excellent support.
GCN Circular 29250
Subject
GRB 210104B: Nanshan/NEXT optical upper limit
Date
2021-01-05T00:33:27Z (4 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
S.Y. Fu (NAOC), Z.P. Zhu (NAOC, HUST), X. Liu, D. Xu (NAOC), X. Gao
(Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 210104B (Laha et al., GCN 29243) using the
NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China.
Observations automatically started at UT on 2020-12-21, i.e., 75 s
after the BAT trigger. We obtained a series of 40 s, 60 s and 90 s
frames in the Sloan r-filter.
No optical source is detected in our stacked image at the Swift/XRT
position (Laha et al., GCN 29243), down to a limiting magnitude of
r~21.0, calibrated with the nearby PanSTARRS field.
GCN Circular 29253
Subject
GRB 210104B: Enhanced Swift-XRT position
Date
2021-01-05T03:08:39Z (4 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 1436 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 210104B, 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 = 53.55295, +37.93051 which is equivalent
to:
RA (J2000): 03h 34m 12.71s
Dec (J2000): +37d 55' 49.8"
with an uncertainty of 1.9 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 29255
Subject
GRB 210104B: Assy optical upper limit
Date
2021-01-05T08:34:20Z (4 years ago)
From
Yerlan Aimuratov at Fesenkov Astrophysical Inst.(FAI) <aimuratov@aphi.kz>
V. Kim (FAI, Pulkovo), I. Reva (FAI), M. Krugov (FAI), Y. Aimuratov
(FAI) report:
We observed the field of GRB 210104B (Laha et al., GCN 29243) with
AZT-20 1.5-m telescope
of Assy-Turgen Observatory (Assy) starting on Jan. 04 (UT) 22:31:15.
We did not find any optical counterpart in our 20x60s stacked image in
the enhanced
XRT position (Evans et al., GCN 29253) down to an upper limit R~23.2
(see also Hu et al., GCN 29249 and Fu et al., GCN 29250).
Preliminary photometry of the filed is the following:
Date UT start t-T0 Filter Exp. OT Err.
UL(3-sigma) FWHM
(mid, days) (s)
(")
2021-01-04 22:31:15 0.06325 r' 20*60 n/d n/d 23.2
2.3
Further observations on this object are not planned except personal
request.
GCN Circular 29256
Subject
GRB 210104B: Swift-XRT refined Analysis
Date
2021-01-05T10:26:27Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J. D. Gropp (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L.
Page (U. Leicester), A.P. Beardmore (U. Leicester), T. Sbarrato
(INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), A.
Tohuvavohu (U. Toronto) and S. Laha report on behalf of the Swift-XRT
team:
We have analysed 6.2 ks of XRT data for GRB 210104B (Laha et al. GCN
Circ. 29243), from 100 s to 39.8 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Evans et al. (GCN Circ. 29253).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.59 (+/-0.04).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.31 (+0.27, -0.25). The
best-fitting absorption column is 1.15 (+0.26, -0.23) x 10^22 cm^-2,
in excess of the Galactic value of 2.7 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 4.3 x 10^-11 (1.3 x 10^-10) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.15 (+0.26, -0.23) x 10^22 cm^-2
Galactic foreground: 2.7 x 10^21 cm^-2
Excess significance: 6.4 sigma
Photon index: 2.31 (+0.27, -0.25)
If the light curve continues to decay with a power-law decay index of
0.59, the count rate at T+24 hours will be 0.019 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.4 x
10^-13 (2.4 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/01015919.
This circular is an official product of the Swift-XRT team.
GCN Circular 29259
Subject
GRB 210104B: Swift/UVOT Upper Limits
Date
2021-01-05T14:18:56Z (4 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and S. L. Laha (GSFC/UMBC/CRESST) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210104B 84 s after the BAT trigger
(Laha et al., GCN Circ. 29243).
No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 29253) 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 84 234 147 >20.5
u_FC 296 546 246 >19.8
white 84 753 172 >20.7
v 625 645 19 >17.6
b 551 743 39 >19.1
u 296 719 265 >19.9
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of
E(B-V) = 0.79 in the direction of the burst (Schlegel et al. 1998).
GCN Circular 29266
Subject
GRB 210104B: Swift-BAT refined analysis
Date
2021-01-05T23:27:10Z (4 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), 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 210104B (trigger #1015919)
(Laha et al., GCN Circ. 29243). The BAT ground-calculated position is
RA, Dec = 53.561, 37.951 deg which is
RA(J2000) = 03h 34m 14.7s
Dec(J2000) = +37d 57' 05.1"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 59%.
The mask-weighted light curve shows a double peaks structure that starts
at ~T0 and ends at ~T+23 s. The two peaks occurs at ~T0 and ~T+11 s,
respectively. T90 (15-350 keV) is 19.94 +- 2.33 sec (estimated error
including systematics).
The time-averaged spectrum from T-0.15 to T+22.76 sec is best fit
by a simple power-law model. The power law index of the time-averaged
spectrum is 1.83 +- 0.14. The fluence in the 15-150 keV band is
1.2 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from
T+10.83 sec in the 15-150 keV band is 1.9 +- 0.3 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/1015919/BA/