GRB 211023B
GCN Circular 30960
Subject
GRB 211023B: Swift detection of a possibly short burst with an optical counterpart
Date
2021-10-23T21:16:59Z (4 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
S. Dichiara (NASA/GSFC/UMCP), J.D. Gropp (PSU), J. A. Kennea (PSU),
H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (U Tampa),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
D. M. Palmer (LANL), B. Sbarufatti (PSU), M. H. Siegel (PSU) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 21:05:52 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 211023B (trigger=1080859). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 170.302, +39.137 which is
RA(J2000) = 11h 21m 12s
Dec(J2000) = +39d 08' 14"
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 2 sec. The peak count rate
was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 21:07:27.3 UT, 95.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 170.31048, 39.13595 which is equivalent
to:
RA(J2000) = 11h 21m 14.52s
Dec(J2000) = +39d 08' 09.4"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 23 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 (2.30 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.5
(+2.51/-2.21) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 97 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 11:21:14.31 = 170.30963
DEC(J2000) = +39:08:08.8 = 39.13578
with a 90%-confidence error radius of about 0.79 arc sec. This position is 3.2
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.32 with a 1-sigma error of about 0.16. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.024.
We note that this is Swift's 1500th GRB.
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/)
GCN Circular 30964
Subject
Swift GRB 211023B: Global MASTER-Net observations report
Date
2021-10-24T03:28:29Z (4 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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 211023B ( S. Dichiara et al., GCN 30960) errorbox 631 sec after notice time and 655 sec after trigger time at 2021-10-23 21:16:47 UT, with upper limit up to 15.2 mag. The observations began at zenith distance = 89 deg. The sun altitude is -58.3 deg.
The galactic latitude b = 68 deg., longitude l = 175 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1762968
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
721 | MASTER-Kislovodsk | P- | 130 | 14.5 |
874 | MASTER-Kislovodsk | P- | 160 | 14.9 |
1252 | MASTER-Kislovodsk | P- | 180 | 15.2 |
The observation and reduction will continue.
The message may be cited.
GCN Circular 30966
Subject
GRB 211023B: Enhanced Swift-XRT position
Date
2021-10-24T06:44:14Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team.
Using 3338 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 211023B, 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 = 170.30871, +39.13534 which is equivalent
to:
RA (J2000): 11h 21m 14.09s
Dec (J2000): +39d 08' 07.2"
with an uncertainty of 2.7 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 30967
Subject
GRB 211023B: Swift-XRT refined Analysis
Date
2021-10-24T07:38:10Z (4 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne
(U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) ,
M. Capalbi (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A.
Kennea (PSU) and S. Dichiara report on behalf of the Swift-XRT team:
We have analysed 6.3 ks of XRT data for GRB 211023B (Dichiara et al.
GCN Circ. 30960), from 79 s to 24.8 ks after the BAT trigger. The data
comprise 8 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Beardmore et al. (GCN Circ.
30966).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.03 (+0.12, -0.10).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.08 (+0.24, -0.22). The
best-fitting absorption column is 9.8 (+6.0, -5.1) x 10^20 cm^-2, in
excess of the Galactic value of 2.3 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 3.2 x 10^-11 (4.0 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 9.8 (+6.0, -5.1) x 10^20 cm^-2
Galactic foreground: 2.3 x 10^20 cm^-2
Excess significance: 2.4 sigma
Photon index: 2.08 (+0.24, -0.22)
If the light curve continues to decay with a power-law decay index of
1.03, the count rate at T+24 hours will be 1.5 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.7 x
10^-14 (5.9 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/01080859.
This circular is an official product of the Swift-XRT team.
GCN Circular 30972
Subject
GRB 211023B: TSHAO optical observation
Date
2021-10-24T13:54:08Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Pozanenko (IKI), I. Reva (FAP), M.Krugov (FAP), S. Belkin (IKI), V.
Kim (FAP), N. Pankov (HSE) report on behalf of GRB-IKI-FuN:
We observed the field of possible short GRB 211023B detected by Swift
(Dichiara et al., GCN 30960) with Zeiss-1000 telescope of Tien Shan
Astronomical Observatory stating on Oct. 23 (UT) 21:17:06. We obtained
series with 120 sec expositions in R-filter.
Within enhanced Swift-XRT position (Beardmore et al., GCN 30966) we do
not detected any source (see upper limits below). In particular we do
not detect possible optical afterglow (Dichiara et al., GCN 30960).
Preliminary photometry of stacked images is following
Date UT start t-T0 Filter Exp. OT Err. UL(3 sigma)
(mid, days) (s)
2021-10-23 21:17:06 0.01127 R 5*120 n/d n/d 18.9
2021-10-23 21:17:06 0.02238 R 21*120 n/d n/d 19.5
The photometry is based on nearby USNO-B1.0 stars.
In addition we found a source in Legacy Survey
(https://www.legacysurvey.org) which is coincident with UVOT detection
(Dichiara et al., GCN 30960).
This is a point-like object at ~0.67 arces distance from UVOT position
and has a LS DR9 photometry
g=24.32, r=24.36, z=23.31
GCN Circular 30973
Subject
GRB 211023B: RATIR Optical and NIR Upper Limits
Date
2021-10-24T14:34:57Z (4 years ago)
From
Alan M Watson at UNAM <alan@astro.unam.mx>
Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H.
Lee (UNAM), Eleonora Troja (GSFC), Michael G. Richer (UNAM), Ori Fox (STScI), J.
Xavier Prochaska (UCSC), Josh Bloom (UCB), Enrico Ramirez-Ruiz (UCSC), Jes��s
Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM), Harvey Moseley (GSFC), Rosa L.
Becerra (UNAM), Simone Dichiara (UMD), and Oc��lotl L��pez (UNAM) report:
We observed the field of GRB 211023B (Dichiara et al., GCN 30960) with the
Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold Johnson
Telescope at the Observatorio Astron��mico Nacional on Sierra San Pedro M��rtir
from 2021/10 24.49 to 2021/10 24.53 UTC (14.54 to 15.54 hours after the BAT
trigger), obtaining a total of 0.73 hours exposure in the r and i bands and 0.30
hours exposure in the Z, Y, J, and H bands.
For a source within the UVOT error circle, in comparison with the SDSS DR9 and
2MASS catalogs, we obtain the following detections and upper limits (3-sigma):
r > 22.4
i > 22.1
Z > 20.6
Y > 20.3
J > 21.0
H > 20.7
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro M��rtir.
GCN Circular 30975
Subject
GRB 211023B: Swift/UVOT Detection
Date
2021-10-24T18:21:49Z (4 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) 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 211023B
98 s after the BAT trigger (Dichiara et al., GCN Circ. 30960).
A source consistent with the XRT position (Beardmore et al. GCN Circ. 30966)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 11:21:14.33 = 170.30971 (deg.)
Dec (J2000) = +39:08:08.8 = 39.13579 (deg.)
with an estimated uncertainty of 0.53 arc sec. (radius, 90% confidence).
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 98 247 147 19.44 +/- 0.11
v 640 1753 136 >18.8
b 566 1679 117 >19.9
u 310 734 265 19.50 +/- 0.20
w1 690 1803 117 >19.3
w2 615 1039 39 >19.9
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.024 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 30976
Subject
GRB 211023B: BOOTES-4/MET and 1.5m OSN optical upper limit
Date
2021-10-24T20:31:50Z (4 years ago)
From
Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>
Y.-D. Hu, V. Casanova, T.-R. Sun, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado, E. Fernandez-Garcia (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 211023B by Swift (S. Dichiara et al. GCNC 30960), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) automatically respond to this burst starting on Oct 23 at 21:06:20 UT (~28 sec after trigger). Due to technical problems, the useful images were obtained only after 21:18:39 UT (~13 min after trigger). The optical afterglow reported by Swift/UVOT (S. Dichiara et al. GCNC 30960, N. P. M. Kuin et al. GCNC 30975) is not detected in the co-added image (10s x 30, clear filter) down to 19.9 mag.
We then triggered the 1.5m OSN telescope in Sierra Nevada Observatory (Granada, Spain) on Oct. 24 03:20 UT (~6.2 hrs after trigger). A series of image were taken in R and I -bands (300s exposures each filter). The optical afterglow is not detected in the co-added image (300s x 12) down to 21.6 mag (R-band).
These non-detections are consistent with the reports by MASTER (Lipunov et al. GCNC 30964), TSHAO (Pozanenko et al. GCNC 30972) and RATIR (Watson et al. GCNC 30973).
We thank the staff at Lijiang observatory and OSN for their excellent support.
GCN Circular 30979
Subject
GRB 211023B: Swift-BAT refined analysis
Date
2021-10-24T20:56:12Z (4 years ago)
From
Hans Krimm at NSF/NASA-GSFC <hkrimm@nsf.gov>
S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), S. Dichiara (NASA/GSFC/UMCP),
H. A. Krimm (NSF), A. Y. Lien (U Tampa), 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 211023B (trigger #1080859)
(Dichiara, et al., GCN Circ. 30960). The BAT ground-calculated position is
RA, Dec = 170.314, 39.133 deg which is
RA(J2000) = 11h 21m 15.3s
Dec(J2000) = +39d 07' 58.7"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 48%.
The mask-weighted light curves shows a single peak from approximately T+0
to T+1.5 seconds. T90 (15-350 keV) is 1.30 +- 0.26 sec (estimated error including
systematics).
The time-averaged spectrum from T-0.01 to T+1.45 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.97 +- 0.24. The fluence in the 15-150 keV band is 1.7 +- 0.3 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.24 sec in the 15-150 keV band
is 2.2 +- 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/1080859/BA/
GCN Circular 30992
Subject
Possible Short GRB 211023B: CAHA 2.2m Detection
Date
2021-10-25T14:56:49Z (4 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/DARK/NBI), C. C.
Thoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC), A.
Guijarro, and P. Martin-Fernandez (both CAHA) report:
We observed the optical afterglow of the potentially short Swift GRB
211023B (Dichiara et al., GCN #30960; Kuin & Dichiara, GCN #30975) with
CAFOS mounted on the 2.2m Telescope at Calar Alto, Almeria, Spain. We
obtained 30 x 90 s in the SDSS i' band under mediocre conditions.
At the position of the GRB afterglow discovered by Swift/UVOT (Kuin &
Dichiara, GCN #30975), we detect a source. Against two Pan-STARRS
comparison stars, we measure:
i' = 22.26 +\- 0.10 mag (AB) at 0.3091 d after the GRB.
We note this faint magnitude is in agreement with both earlier (Lipunov
et al., GCN #30964; Pozanenko et al., GCN #30972; Yu et al., GCN
#30976), simultaneous (Yu et al., GCN #30976), and later (Watson et al.,
GCN #30973) non-detections.
GCN Circular 31000
Subject
GRB 211023B: LDT Optical Afterglow Detection
Date
2021-10-25T23:11:12Z (4 years ago)
From
Brendan O'Connor at UMD <oconnorb@umd.edu>
B. O'Connor (UMD, GWU),S.B. Cenko (UMD,NASA-GSFC),
E. Troja (UMD, NASA-GSFC),A.Gottlieb (UMD,NASA-GSFC),
S.Dichiara (PSU),A. Kutyrev (UMD,NASA-GSFC),
S. Veilleux (UMD)
We observed the field of GRB 211023B (Dichiara et al., GCN 30960)
using the Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery
Telescope (LDT) at Happy Jack, AZ. Observations began on October 25,
2021 at 11:42:14 UT (~1.61 d after the GRB), and were performed in
r-band for a total of 18x150 s exposures under poor conditions.
We detect a source coincident with the position of the optical counterpart
reported by UVOT (Kuin et al., GCN 30975) and CAHA (Kann et al., GCN 30992).
We measure a brightness of r~23 AB mag, brighter than the archival object
reported by Pozanenko et al. (GCN 30972). We do not detect any other source
within 5" radius of the UVOT position with a 3-sigma upper limit r>24.0 mag.
Given the non-detection at ~15 hours (Watson et al., GCN 30973),
our detection implies a shallow temporal decay index beta<0.6,
assuming a power-law decline as F~t^-beta. While this may be due
in part to the underlying source (Pozanenko et al., GCN 30972),
we note that the same flattening is also observed in X-rays by Swift/XRT.
Therefore, we strongly encourage continued follow-up of this source.
Magnitudes are calibrated against the SDSS catalog and are not corrected
for Galactic extinction.
We thank the staff of the Lowell Discovery Telescope for assistance
with these observations.
GCN Circular 31002
Subject
GRB 211023B: Gemini-North Optical Observations
Date
2021-10-26T01:38:16Z (4 years ago)
From
Jillian Rastinejad at Northwestern Univ. <jillianrastinejad2024@u.northwestern.edu>
J. Rastinejad, K. Paterson, W. Fong, C. Kilpatrick, A. Rouco Escorial (Northwestern), Antonino Cucchiara (College of Marin) report on behalf of a larger collaboration:
We observed the location of GRB 211023B (Dichiara et al. GCNC 30960) over two nights with the Gemini Multi-Object Spectrograph (GMOS) mounted on Gemini-North under Program GN-2021B-Q-109. We obtained 11x60-sec and 20x60-sec imaging in i-band at a mid-time of 2021 October 25.63 UT (0.7484 days post-burst) and 2021October 24.62 UT (1.745 days post-burst), respectively, both at a median airmass of 1.9. At 1.745 days post-burst, we detect a source consistent with both the UVOT position and the previously reported Legacy Survey source (Kuin et al. GCN 30975, Pozanenko et al. GCN 30972). Calibrated to SDSS, we measure a brightness of i_AB = 23.1 +/- 0.1 mag at seeing < 0.8'' for this source.
This is consistent with previously reported upper limits (Watson et al., GCN 30973, Hu et al. GCN 30976, Pozanenko et al. GCN 30972) and indicates significant fading from the i-band measurement reported by Kann et al. (GCN 30995) at 0.3091 days post-burst. At present, the source appears marginally extended, and it is very likely that the underlying host galaxy is contributing significantly to our measured flux (based on the expected i-band magnitude of the host from interpolating Legacy Survey DR9 photometry; Dey et al., 2019).
Further observations are planned to monitor the variability of the source. We thank Jennifer Andrews and additional Gemini staff for the rapid planning and execution of these observations.
GCN Circular 31003
Subject
GRB 211023B: Mondy optical afterglow confirmation
Date
2021-10-26T11:09:14Z (4 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Pozanenko (IKI), S. Belkin (IKI), E. Klunko (ISTP), N. Pankov (HSE),
report on behalf of GRB IKI FuN:
We observed the field of GRB 211023B (Dichiara et al., GCN 30960) with
AZT-33IK telescope of Sayan observatory (Mondy) starting on 2021-10-23
(UT) 21:23:21. We obtained 60 images in R-filter. We confirm afterglow
of the GRB 211023B (Dichiara et al., GCN 30960; Kuin et al. GCN 30975;
Kann et al. GCN 30995; O'Connor et al., GCN 31000; Rastinejad et al.,
GCN 31002). Preliminary photometry of the afterglow in stacked images
is following
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2021-10-23 21:23:21 0.15613 R 15*60 20.46 0.31 20.5
2021-10-23 21:23:21 0.03297 R 60*60 20.97 0.40 20.9
The photometry is based on the nearby USNO-B1.0 stars
RA DEC R2
11:21:12.41280 +39:08:38.1120 15.33
11:21:05.20872 +39:04:33.9600 14.18
We note the obtained magnitudes are in agreement with non-detections of
the optical counterpart (Lipunov et al., GCN 30964; Pozanenko et al.,
GCN 30972; Watson et al., GCN 30973; Yu et al., GCN 30976).
GCN Circular 31016
Subject
GRB 211023B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
Date
2021-10-28T01:28:54Z (4 years ago)
From
Bruce Grossan at LBNL/UCB SSL <Bruce_Grossan@lbl.gov>
B. Grossan (UCB, NU), T. Komesh (NU), Z. Maksut (NU), M. Krugov (FAI), E. Linder (UCB, NU), E. Abdikamalov (NU), G. F. Smoot (HKUST, UCB, NU), report on behalf of the Energetic Cosmos Laboratory:
The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) observed the field of GRB 211023B soon after receipt an automated GCN / BAT position alert, observing in Sloan g', r' and i' bands, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14).
We started observations at 21:26:33 UT on 2021-10-23, 1241 s after the BAT trigger. Observations were made partly cloudy conditions starting at only about 18 deg. target altitude. No source consistent with the XRT (P. Evans et al., GCN Circ. 30966) or UVOT position (S. Dichiara; GCN Circ. 30960) was detected. Note that these observations provide essentially full-time coverage, simultaneous in all three bands. We report the following results:
start time t-t0(s) end time UL g' UL r' ULi' exposure_time (s)
------------ -------- ------------ ------ ------ ------ --------------------
21:26:33 1241 21:27:33 17.6 18.7 17.8 60
21:27:56 1324 22:47:56 18.5 19.5 18.7 300
start time is in UT. t-t0(s) gives the time since trigger, in seconds. UL g', r', i', gives the 5 sigma upper limit sensitivity in magnitudes in the respective filter, for images co-added to the given exposure time. The first row in the table corresponds to co-adds of an initial short exposure image sequence of 7.5 s for g' and i', and 0.3 s for r' (these sub-second exposures are read-noise suppressed by our EMCCD cameras, with high gain electron multiplication active; other images are taken in conventional CCD operation mode). The second row corresponds to co-adds from a continuing series of 15 s exposures for g' and i', and 3 s for r', uninterrupted for the 80 minutes. Calibration was done with the 2-5 bright Pan-STARRS catalog stars on our images.
We caution the reader that these are preliminary results, without color or other corrections. Please also note that times are approximate.
----------------------------------
NU = Nazarbayev University, Nur-Sultan, Kazakhstan
UCB = University of California, Berkeley, USA
HKUST = Hong Kong University of Science and Technology
FAI = Fesenkov Astrophysical Institute, Kazakhstan
The NUTTelA-TAO Team acknowledges the support of the staff of the Assy-Turgen Astrophysical Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical Institute, Almaty, Kazkhstan.
GCN Circular 31031
Subject
GRB 211023B: MITSuME Akeno optical upper limits
Date
2021-11-02T11:51:41Z (4 years ago)
From
Yuri Imai at Tokyo Inst of Tech <imai@hp.phys.titech.ac.jp>
R. Hosokawa, Y. Imai, K. L. Murata, M. Niwano, Y. Takamatsu, N. Ito,
R. Noto, S. Sato, M. Takaku, R. Yamaguchi, Y. Yatsu, and N. Kawai
(TokyoTech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 211023B (S. Dichiara et al. GCN Circular
#30960, V. Lipunov et al. GCN Circular #30964, A.P. Beardmore et al.
GCN Circular #30966, A.P. Beardmore et al. GCN Circular #30967, A.
Pozanenko et al. GCN Circular #30972, Alan M. Watson et al. GCN
Circular #30973, N. P. M. Kuin et al. GCN Circular #30975, Y.-D. Hu et
al. GCN Circular #30976, S. Laha et al. GCN Circular #30979, D. A.
Kann et al. GCN Circular #30992, B. O'Connor et al. GCN Circular
#31000, J. Rastinejad et al. GCN Circular #31002, A. Pozanenko et al.
GCN Circular #31003, B. Grossan et al. GCN Circular #31016) with the
optical three color (g', Rc, and Ic) CCD cameras attached to the
MITSuME 50 cm telescope Akeno. The observation with a series of 60 sec
exposures started at 21-10-24 17:18:57 UT (20.2 hours after Swift
trigger). We stacked the images with good conditions. We did not
detect any uncatalogued sources within the UVOT error region (S.
Dichiara et al. GCN Circular #30960). We obtained the 5-sigma limits
of the stacked images as follows.
T0+[days] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
2.9 2021-10-26 19:25:18 2160 g'>19.5, Rc>19.6, Ic>18.7
3.9 2021-10-27 19:10:47 4020 g'>19.5, Rc>20.1, Ic>19.4
4.9 2021-10-28 19:02:53 7020 g'>19.8, Rc>20.1, Ic>19.3
5.9 2021-10-29 18:56:59 6120 g'>20.3, Rc>20.5, Ic>19.9
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used PS1 catalog for flux calibration.
The magnitudes are expressed in the AB system.
The images were processed in real-time through the MITSuME GPU
reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages
4-24; https://github.com/MNiwano/Eclaire).
GCN Circular 31038
Subject
GRB 211023B: Subaru optical observation
Date
2021-11-04T10:42:09Z (4 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
T. Sakamoto (AGU), G.S.H. Paek (SNU), Y. Urata (NCU),
E. Troja (NASA/GSFC), M. Im (SNU), K. Aoki (NAOJ)
report on behalf of Subaru GRB team:
We observed the field of GRB 211023B (Dichiara et al., GCN Circ. 30960)
with Hyper Suprime-Cam (HSC) on the Subaru 8.2 m telescope starting from
13:36 on October 28 about 4.7 days after the trigger. Observations were
performed in the r filter for a total of 4800 s (32 x 150 s) exposure.
At a position consistent with the UVOT localization (Kuin & Dichiara, GCN Circ. 30975)
and the Legacy Survey object (Pozanenko et al. GCN 30972), we detect an optical
source with magnitude r~23.6 AB. Since the source appears clearly extended in our images
and its brightness is consistent with the Gemini-North observation (Rastinejad et al., GCN Circ. 31002),
archival HSC g-band images of March 2016, and CFHT archival r-band images of September 2020,
we conclude that the source detected by Subaru is dominated by the host galaxy contribution,
in agreement with Rastinejad et al. (GCN Circ. 31002).
We would like to thank the Subaru director, Dr. Michitoshi Yoshida for
approving our ToO, and Dr. Tsuyoshi Terai and Dr. Ichi Tanaka for supporting
our observation.
GCN Circular 31107
Subject
GRB 211023B: LBT likely spectroscopic redshift of the host galaxy
Date
2021-11-23T16:00:07Z (4 years ago)
From
Andrea Rossi at INAF <andrea.rossi@inaf.it>
A. Rossi, E. Palazzi, L. Amati, E. Pian (INAF-OAS), D. B. Malesani
(Univ. Radboud and DAWN/NBI), S. Savaglio (UNICAL), P. D'Avanzo
(INAF/OABr), and V. D'Elia (SSDC & INAF-OAR), M. De Pasquale (University
of Messina),�� report on behalf of the CIBO collaboration:
We report the results of the photometric and spectroscopic follow-up of
the short GRB 211023B (Dichiara et al., GCN Circ. 30960) obtained with
the Multi-Object Double Spectrographs (MODS) instrument mounted on the
2x8.4-m LBT telescope (Mt Graham, AZ, USA). Data were obtained at the
mid time of 12:40 UT on 2021-11-06, ~13.6 days after the burst trigger.
At the position of the UVOT localization (Kuin & Dichiara, GCN 30975)
and the Legacy Survey object (Pozanenko et al., GCN 30972), we detect
the GRB host galaxy (Sakamato et al. GCN 31038, Rastinejad et al. GCN
31002). We measure the following AB magnitudes:
g = 24.02+-0.17
r = 23.99+-0.15
calibrated against Pan-STARRS field stars and not corrected for Galactic
extinction.
Spectroscopy of the source was obtained for a total of 4550s, covering
the wavelength range 3200-10000 AA.Continuum is faintly detected over
the wavelength range 3200-10000 AA, and a single emission line is
visible at ~6940 AA. The most likely interpretation is [O II] at z =
0.862. At this redshift, [O III] would unfortunately fall on top of a
region affected by sky lines, so its non-detection is not very
constraining. Other interpretations are less likely. We can disregard
Lyalpha, since there is no drop in the continuum blueward of the line.
We deem Halpha unlikely, as the corresponding redshift z = 0.057 would
imply an extremely faint host galaxy (absolute magnitude ~ -13), and we
don't see the expected [O III] and Hbeta lines. The interpretation of
the observed feature as [O III] 5008 seems to be also unlikely as we
would expect to detect hints of [O III] 4959 as well as Halpha which
would fall in a wavelength region clean of skylines.
Assuming the redshift z=0.862, standard cosmology (Planck 2016) and
Swift/BAT refined and on-line automated spectral analysis (Laha et al.,
GCN 30979, and http://gcn.gsfc.nasa.gov/notices_s/1080859/BA/
<http://gcn.gsfc.nasa.gov/notices_s/1080859/BA/>) we estimate an
isotropic-equivalent radiated energy Eiso (1-10000 keV) of about
(0.9-1.2)x E^51 erg, which is typical of short GRBs. However, we note that:
a) despite its short duration, the burst has a rather soft spectrum
(simple power with index ~2) which is consistent with a spectral peak
energy Ep close to (or even below) the BAT low-energy threshold and
would imply a rest-frame peak energy Ep,i < ~30-40 keV, thus locating
this GRB in the region of the Ep,i - Eiso plane populated by long GRBs.
The preliminary automatic modelling with a cut-off power-law or a Band
function is consistent with a larger Ep,i, which would make this burst
more similar to other short GRBs, but with a very large uncertainty.
b) the soft spectra and short duration put GRB 211023B closer to the
region populated by long GRBs than to to the one populated by short
events also in the HR-T90 diagram, even though it is still consistent
with belonging to the tail of the distribution of short GRBs in this plane.
We acknowledge the excellent support from the LBTO and LBT-INAF staff,
particularly O. Kuhn, S. Allanson, F. Cusano, S. Bisogni, and D. Paris,
in obtaining these observations.