GRB 210205A
GCN Circular 29526
Subject
GRB 210205A: observations with the 3.6m DOT, a potential dark burst?
Date
2021-02-18T09:07:31Z (5 years ago)
From
Rahul Gupta at ARIES, India <rahulbhu.c157@gmail.com>
S. B. Pandey, R. Gupta, A. Kumar, Dimple, A. Ghosh, A. Aryan, and K. Misra
(ARIES) on behalf of a larger collaboration report:
GRB 210205A was detected by the Swift Burst Alert Telescope (BAT) at
11:11:17 UT on 5th Feb 2021 (GCN 29397). The prompt emission mask-weighted
BAT light curve consists of a multi-peaked structure with a T90 duration of
22.70 +- 4.18 sec in 15-350 keV energy range (GCN 29409). We compare the
reported value of BAT fluence and peak photon flux for this GRB (GCN 29409)
with all the BAT detected samples, we find this burst is positioned nearly
the middle of this distribution. The Swift XRT detected an X-ray afterglow
~ 134.7 sec after the BAT trigger (GCN 29397). The X-ray light curve could
be best described with a simple power-law model with a temporal index of
1.100 (+0.092, -0.101) and the afterglow is fainter (0.016 x 10^-11
erg/cm2/s, at 11-hour post burst) than typical X-ray afterglows. As no
red-shift has been reported for this source, we modeled the time-averaged
XRT spectrum (T0 + 143 to 39716 s) considering red-shift = 2, roughly
average red-shift value for long GRBs. The spectrum could be modeled using
an absorption power-law with following spectral parameters: NH_host= 5.34
(-4.58,+6.18) * 10^{22} cm^{-2} and \beta_x= 1.11 (-0.37,+0.40).
Considering the adiabatic deceleration without energy injection, closure
relations indicate that the X-ray afterglow could be best described with
\nu > \nu_c spectral regime for ISM as well as WIND medium for the electron
energy index p ~ 2.22.
Many optical telescopes searched for the optical afterglow but no
counterpart associated with this burst was detected to deeper limits at
early epochs(GCN 29397, 29398, 29400, 29401, 29402, 29403, and 29406). So,
we performed the search for the optical counterpart of this XRT localized
GRB 210205A (GCN 29399) using the 4Kx4K CCD Imager (Pandey et al. 2017,
arXiv:1711.05422v1) mounted at the axial port of the 3.6m Devasthal Optical
Telescope (DOT) of ARIES Nainital. Multiple frames having exposure times of
300s each were taken in R and I filters. We do not find any evidence of an
afterglow candidate inside the XRT error circle, consistent with other
non-detections. We constrain the following 3-sigma upper limits.
T-T0 (days) Exp. (s) Filter OT UL Telescope
1.0921 2*300 R NA 22.8 3.6m DOT
1.1033 2*300 I NA 22.6 3.6m DOT
The limiting magnitudes quoted are not corrected for the Galactic and Host
extinction in the direction of the burst. Considering no spectral break
between X-ray and optical frequencies, we extrapolated the X-ray spectral
index towards optical frequencies. We found that using reported limiting
values at optical (Galactic extinction corrected) roughly lie below the
extrapolated X-ray power-law slope, suggesting that this burst could be a
potential dark GRB candidate either highly extinguished or as a high
redshift event.
3.6m Devasthal Optical Telescope (DOT) is a recently commissioned facility
in the Northern Himalayan region of India (long:79 41 04E, lat:29 21 40N,
alt:2540m) owned and operated by the Aryabhatta Research Institute of
Observational Sciences (ARIES), Nainital (https://www.aries.res.in).
Authors of this GCN circular thankfully acknowledge consistent support from
the staff members to run and maintain the 3.6m DOT. This circular may be
cited.
GCN Circular 29409
Subject
GRB 210205A: Swift-BAT refined analysis
Date
2021-02-06T03:36:38Z (5 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
S. Dichiara (NASA/GSFC/UMCP), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), 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 210205A (trigger #1030629)
(Dichiara et al., GCN Circ. 29397). The BAT ground-calculated position is
RA, Dec = 347.264, 56.311 deg which is
RA(J2000) = 23h 09m 03.3s
Dec(J2000) = +56d 18' 41.2"
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 18%.
The mask-weighted light curve shows a multi-peaked structure that
starts at ~ T-7 s and ends at ~T+20 s. The main peak in the structure
occurs at ~T+6 s. T90 (15-350 keV) is 22.70 +- 4.18 sec (estimated
error including systematics).
The time-averaged spectrum from T-7.35 to T+20.07 sec is best fit
by a simple power-law model. The power law index of the time-averaged
spectrum is 2.27 +- 0.31. The fluence in the 15-150 keV band is
8.7 +- 1.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from
T+5.98 sec in the 15-150 keV band is 1.6 +- 0.5 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/1030629/BA/
GCN Circular 29407
Subject
GRB 210205A: Swift-XRT refined Analysis
Date
2021-02-05T22:52:15Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M.
Capalbi (INAF-IASFPA), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto),
B. Sbarufatti (PSU) and S. Dichiara report on behalf of the Swift-XRT
team:
We have analysed 6.1 ks of XRT data for GRB 210205A (Dichiara et al.
GCN Circ. 29397), from 143 s to 28.3 ks after the BAT trigger. The
data are entirely in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Osborne et al. (GCN Circ. 29399).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.10 (+0.10, -0.11).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.1 (+0.5, -0.4). The
best-fitting absorption column is 8.0 (+4.0, -2.8) x 10^21 cm^-2,
consistent with the Galactic value of 5.1 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 (8.2 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 8.0 (+4.0, -2.8) x 10^21 cm^-2
Galactic foreground: 5.1 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.1 (+0.5, -0.4)
If the light curve continues to decay with a power-law decay index of
1.10, the count rate at T+24 hours will be 1.6 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.8 x
10^-14 (1.3 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/01030629.
This circular is an official product of the Swift-XRT team.
GCN Circular 29406
Subject
GRB 210205A: MITSuME Ishigaki optical observation
Date
2021-02-05T22:01:18Z (5 years ago)
From
Takashi Horiuchi at Ishigakijima Astronomical Obs <takashi.horiuchi@nao.ac.jp>
Takashi Horiuchi, Hidekazu Hanayama (NAOJ), Katsuhiro L. Murata,
Yoichi Yatsu, Nobuyuki Kawai (Tokyo Tech) report on behalf of the
MITSuME collaboration:
We observed the field of GRB 210205A (Dichiara et al., GCN 29397)
with the optical three color (g', Rc, and Ic) CCD cameras attached to
the 105 cm Murikabushi telescope of Ishigakijima Astronomical
Observatory, Okinawa, Japan.
The observation with a series of 60 sec exposures started on
2021-02���05 11:22:29 UT (2 min after Swift BAT trigger).
We stacked the 25 images and did not find any new point sources
other than the USNO-B1.0 sources from the stacked images.
We obtained the SN = 10 limits as follows.
T0+[min] MID-UT T-EXP[sec] SN=10 limits
------------------------------------------------------------------------------------------------
2 2021-02-05T11:36:37 1500 g' > 18.7, Rc > 19.0, Ic > 17.8
------------------------------------------------------------------------------------------------
GCN Circular 29403
Subject
GRB 210205A: Swift/UVOT Upper Limits
Date
2021-02-05T18:16:08Z (5 years ago)
From
Alexander Belles at PSU/Swift <aub1461@psu.edu>
A. Belles (PSU) and S. Dichiara (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210205A
139 s after the BAT trigger (Dichiara et al., GCN Circ. 29397).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 29399)
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 139 289 147 >20.5
white 139 4057 344 >20.6
v 4268 4468 197 >19.4
b 3652 5159 265 >20.1
u 297 5084 255 >19.7
w1 4678 4878 197 >19.9
m2 4473 4673 197 >20.8
w2 4063 4263 197 >19.3
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.716 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 29402
Subject
Swift GRB 210205A: Global MASTER-Net observations report
Date
2021-02-05T17:40:09Z (5 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin,
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov, D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gres, N.M. Budnev, O.Ershova
(Irkutsk State University, API),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko
(Blagoveschensk Educational State University)
MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 210205A ( S. Dichiara et al., GCN 29397) errorbox 21040 sec after notice time and 21101 sec after trigger time at 2021-02-05 17:02:58 UT, with upper limit up to 17.4 mag. The observations began at zenith distance = 49 deg. The sun altitude is -22.7 deg.
The galactic latitude b = -4 deg., longitude l = 109 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1540460
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
21191 | MASTER-Tavrida | C | 180 | 14.5 |
21191 | MASTER-Tavrida | C | 180 | 14.8 |
22639 | MASTER-Tavrida | C | 180 | 17.4 |
22639 | MASTER-Tavrida | C | 180 | 17.1 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 29401
Subject
GRB 210205A: Nanshan/NEXT optical upper limit
Date
2021-02-05T16:20:03Z (5 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
S.Y. Fu (NAOC), Z.P. Zhu (HUST,NAOC), X. Liu, D. Xu (NAOC), X. Gao
(Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 210205A (Dichiara et al., GCN 29397) using
the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We obtained
3x40 s, 4x60 s, 12x90 s frames in the Sloan r-band, starting at 12:09:46
UT on 2021-02-05, i.e., 58.5 min after the BAT trigger.
No optical source is detected in our stacked image at the enhanced XRT
position (Osborne et al., GCN 29399), down to a limiting magnitude of
r~19.9, calibrated with the nearby PanSTARRS field.
GCN Circular 29400
Subject
GRB 210205A: BOOTES-4/MET optical upper limit
Date
2021-02-05T15:11:13Z (5 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, M. A. Castro Tirado (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), S. Guziy (Univ. of Nikolaev) and D. R. Xiong, Y. F. Fan, J. M. Bai, C. J. Wang, Y. X. Xin, X. H. Zhao (Yunnan Observatories of CAS) on behalf of a larger collaboration, report:
Following the detection of GRB 210205A by Swift (Dichiara et al. GCNC 29397), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) started to gather images after the twilight as soon as it was possible. No new source is detected within the Swift/XRT enhanced position (Osborne et al. GCNC 29399) down to 18.3 mag in the co-added z-band images (7x120 s) starting at 12:22 UT. The non-detection is consistent with the limits reported by both Swift/UVOT (Dichiara et al. GCNC 29397) and GWAC-F60A (Xin et al. GCNC 29398).
We thank the staff at Lijiang observatory for their excellent support.
GCN Circular 29399
Subject
GRB 210205A: Enhanced Swift-XRT position
Date
2021-02-05T14:07:37Z (5 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1148 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 210205A, 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 = 347.21907, +56.29649 which is equivalent
to:
RA (J2000): 23h 08m 52.58s
Dec (J2000): +56d 17' 47.4"
with an uncertainty of 2.0 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 29398
Subject
GRB 210205A： GWAC-F60A optical upper limit
Date
2021-02-05T11:50:51Z (5 years ago)
From
Liping Xin at NAOC, SVOM <xlp@nao.cas.cn>
L. P. Xin(NAOC), J. Wang(GXU), C. Gao(GXU), X. H. Han(NAOC), J. Y. Wei(NAOC),
G. W. LI(NAOC), L. H. Li(NAOC), C. Wu(NAOC), X. G. Wang(GXU),
E. W. Liang (GXU), R. S. Zhang(NAOC), Y. L. Qiu(NAOC),
and J. S. Deng(NAOC) report:
We began to observe GRB 210205A (Dichiaraet al., GCN 29397)
with Xinglong GWAC-F60A telescope, China,
at 11:13:26 (UT), 5th. Feb. 2021, about 129 sec after the burst.
A series of R, I, and B band images were obtained.
Preliminary analysis shows that no any new optical source
are found in single images within the XRT errorbox (Dichiaraet al., GCN 29397).
The 3 sigma upper limit is about 17.3 mag in R band
at the mean time of 134 sec after the burst,
calibrated to the USNO B1.0 catalog.
GCN Circular 29397
Subject
GRB 210205A: Swift detection of a burst
Date
2021-02-05T11:27:17Z (5 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
S. Dichiara (NASA/GSFC/UMCP), E. Ambrosi (INAF-IASFPA),
S. D. Barthelmy (GSFC), V. D'Elia (SSDC), P. A. Evans (U Leicester),
J.D. Gropp (PSU), H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL),
A. Y. Lien (GSFC/UMBC) and K. L. Page (U Leicester) report on behalf
of the Neil Gehrels Swift Observatory Team:
At 11:11:17 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210205A (trigger=1030629). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 347.257, +56.312 which is
RA(J2000) = 23h 09m 02s
Dec(J2000) = +56d 18' 45"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a multi-peak
structure with a duration of about 35 sec. The peak count rate
was ~1000 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 11:13:32.2 UT, 134.7 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 347.2214, 56.2943 which
is equivalent to:
RA(J2000) = 23h 08m 53.13s
Dec(J2000) = +56d 17' 39.4"
with an uncertainty of 2.6 arcseconds (radius, 90% containment). This
location is 95 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 consistent with the Galactic value of 5.15
x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 138 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 47% 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 large, but uncertain, extinction expected.
Burst Advocate for this burst is S. Dichiara (dichiara AT umd.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/)