GRB 231129A

J.D. Gropp (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII),
D. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 05:05:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 231129A (trigger=1199764).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 317.536, +41.544 which is 
   RA(J2000) = 21h 10m 09s
   Dec(J2000) = +41d 32' 37"
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 120 sec.  The peak count rate
was ~3700 counts/sec (15-350 keV), at ~90 sec after the trigger. 

The XRT began observing the field at 05:07:51.1 UT, 112.0 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 317.54581, 41.52062 which
is equivalent to:
   RA(J2000)  = 21h 10m 10.99s
   Dec(J2000) = +41d 31' 14.2"
with an uncertainty of 4.0 arcseconds (radius, 90% containment). This
location is 88 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. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

The initial flux in the 0.1 s image was 3.05e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 120 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. 
Results from the list of sources generated on-board are not available at this
time. No correction has been made for the large, but uncertain, extinction
expected. 

Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.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/)

S.Mereghetti (INAF, IASF-Milano), D.Gotz (CEA, Saclay), C.Ferrigno, E.Bozzo, V.Savchenko (ISDC, Versoix), L.Ducci (IAAT, Germany and ISDC, Versoix) and J.Borkowski (CAMK, Torun) report:

a gamma ray burst lasting about 150 s has been detected by IBAS in the  IBIS/ISGRI data at 05:05:59  UT of November 25, 2023.  The burst has also been detected by Swift (Gropp et al. GCN 35208
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 )

The refined coordinates (J2000) are:
R.A.=  317.53411 deg
DEC.=  +41.51942 deg
with an uncertainty of 1.5  arcmin (90% c.l.).

The burst had a peak flux of about 0.5 ph/cm2/s (20-200 keV, 1-s integration time) and a fluence in the same energy range of about 6e-7 erg/cmq.

A plot of the light curve will  be posted at 
http://ibas.iasf-milano.inaf.it/IBAS_Results.html

Wen-Long Zhang, Shao-Lin Xiong report on behalf of the GECAM team:

GECAM-C was triggered in-flight by a long burst, GRB 231129A, at 2023-11-29T05:06:01.850 UTC (T0), which was also observed by Swift/BAT (GCN #35208
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 ) and INTEGRAL (GCN #35209
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 ). 

According to the realtime alert data, the GECAM-C light curve shows roughly two peaks with a total duration of ~80 sec (15-1050 keV). 

The time-averaged spectrum of GECAM-C realtime data from about T0 to T0+4 s could be
adequately fit by a cut-off power-law with a fluence about 1.84E-6 erg/cm^2 in 20-1000 keV. 

GECAM location is consistent with that of Swift/BAT and INTEGRAL within the error.
We note that these results are based on realtime alert data and thus very preliminary. Refined analysis will be reported later.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).

D.N. Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU), J.P. Osborne
(U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U.
Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E.
Ambrosi  (INAF-IASFPA)	and P.A. Evans report on behalf of the
Swift-XRT team:

We have analysed 7.0 ks of XRT data for GRB 231129A, from 115 s to 43.8
ks after the  BAT trigger. The data comprise 174 s in Windowed Timing
(WT) mode with the remainder in Photon Counting (PC) mode. The refined
XRT position is RA, Dec = 317.5437, +41.5206 which is equivalent to:

RA (J2000): 21 10 10.49
Dec(J2000): +41 31 14.2

with an uncertainty of 3.5 arcsec (radius, 90% confidence).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=4.86 (+/-0.21). At T+165 s  the decay
steepens to an alpha of 6.44 (+0.28, -0.24) before breaking again at
T+308 s to a final decay with index alpha=0.83 (+0.05, -0.06).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.83 (+/-0.07). The
best-fitting absorption column is  1.09 (+/-0.08) x 10^22 cm^-2, in
excess of the Galactic value of 5.9 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.18 (+0.31, -0.29)
and a best-fitting absorption column of 1.6 (+/-0.4) x 10^22 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 5.0 x 10^-11 (1.2 x 10^-10) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.6 (+/-0.4) x 10^22 cm^-2
Galactic foreground: 5.9 x 10^21 cm^-2
Excess significance: 4.5 sigma
Photon index:	     2.18 (+0.31, -0.29)

If the light curve continues to decay with a power-law decay index of
0.83, the count rate at T+24 hours will be 0.014 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.2 x
10^-13 (1.8 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/01199764.

This circular is an official product of the Swift-XRT team.

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2261 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 231129A, 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 = 317.54381, +41.52204 which is equivalent
to:

RA (J2000): 21h 10m 10.51s
Dec (J2000): +41d 31' 19.4"

with an uncertainty of 2.2 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.

S. Belkin (IKI), E. Klunko (ISTP), A. Pozanenko (IKI), N. Pankov (IKI, HSE) report on behalf of GRB IKI FuN:

We observed the field of Swift GRB 231129A (Gropp et al., GCN 35208
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 ; Mereghetti et al., GCN 35209
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 ; Zhang et al., GCN 35210
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 ) with AZT-33IK telescope of Mondy observatory in R-filter on 2023-11-29 starting (UT) 10:43:30. We do not detect any optical objects within the enhanced Swift-XRT error box (Goad et al., GCN 35220
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 ). Preliminary photometry of a stacked image is following

Date        UT start   t-T0          Exp.  Filter  OT   Err. UL(3sigma)
                                           (mid, days)  (s)

2023-11-29  10:43:30   0.25730       33x120 R      n/d  n/d  23.1

The photometry is based on nearby USNO-B1.0 stars.
USNO-B1.0
RA DEC R2
21:10:16.6747200 +41:33:09.000000 17.36
21:10:16.0548000 +41:32:49.822800 18.82

A. A. Breeveld (UCL-MSSL) and J. D. Gropp (PSU) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231129A (Gropp et al., GCN circ. 35208
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 ; Mereghetti et al., GCN circ. 35209
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 ; Zhang et al., GCN circ. 35210
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 ) 120 s after the BAT trigger (Gropp et al., GCN Circ. 35208
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 ).
No optical afterglow consistent with the XRT position (Goad et al., GCN Circ. 35220
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 ) 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           120          270          147         >20.5
white              120         4158          344         >20.8
v                 4369         4568          197         >18.9
b                 3753         3953          197         >19.4
u                  333         5122          275         >19.9
w1                4780         4980          197         >18.8
m2                4574         4773          197         >18.9
w2                4164         4364          197         >19.2

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.164 in the direction of the burst (Schlegel et al. 1998).

X. Liu, Z.P. Zhu, J. An, S.Q. Jiang, S.Y. Fu, T.H. Lu, D. Xu (NAOC), S.W Luo, M.M. Yang, Z. K. Feng, L.F. Huo (XJTS) report on behalf of a large collaboration:

We observed the field of GRB 231129A detected by Swift (J.D. Gropp, GCN 35208
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 ), INTEGRAL (S.Mereghetti et al., GCN 35209
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 ), and GECAM-C (Wen-Long Zhang et al., GCN 35210
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 ), using the  100cm C telescope (100C) located at Altay, Xinjiang, China. Observations started at 12:13:36.29 UT on 2023-11-29, i.e., 7.13 hr after the Swift/BAT trigger, and 30*120s frames are obtained in the Sloan-r band.

No credible optical transient is detected in our stacked images within the refined Swift/XRT error region (Burrows et al., GCN 35218
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 ), down to a 3-sigma upper limit of r > 21.6 mag, calibrated with nearby PanSTARRS stars and not corrected for Galactic extinction.

Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, I. Perez-Garcia, M.D. Caballero-Garcia, S.-Y. Wu, R. Sanchez-Ramirez, S. Guziy (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar (UMA) and I. M. Carrasco-Garcia (SMA) and I. H. Park (SKKU), on behalf of a larger collaboration, report:

Following the detection of GRB 231129A by Swift (Gropp et al. GCNC 35208), INTEGRAL (Mereghetti et al. GCNC 35209) and GECAM-C (Zhang et al. GCNC 35210), the BOOTES-5/JGT 0.6m robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically observed the GRB location starting on Nov. 29, 05:07 UT (~ 61 s after trigger). No new optical source is detected on the co-added image (15 x 10 s, clear filter) within the Swift/XRT error region (Goad et al. GCNC 35220) down to 19.9 mag, which is consistent with reports from MASTER (Lipunov et al. GCNC 35212), Mondy (Belkin et al. GCNC 35232), UVOT (Breeveld et al. GCNC 35233) and JinShan (Liu et al. GCNC 35237).

We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for their excellent support.

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
M. Moss (GSFC), T. Parsotan (GSFC/UMBC),
T. Sakamoto (AGU),M. Stamatikos (OSU)
(i.e. the Swift-BAT team):

Using the data set from T-61 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 231129A (trigger #1199764)
(Gropp et al., GCN Circ. 35208
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 ).  The BAT ground-calculated position is
RA, Dec = 317.541, 41.530 deg which is
   RA(J2000)  =  21h 10m 09.8s
   Dec(J2000) = +41d 31' 48.3"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 46%.

The BAT  light curve shows a complex structure with a duration of ~ 130 sec.
T90 (15-350 keV) is 105.46 +- 1.83 sec (estimated error including systematics).

The time-averaged spectrum from T-1.75 to T+118.97 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.35 +- 0.17,
and Epeak of 83.7 +- 14.6 keV (chi squared 51.44 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.3 +- 0.0 x 10^-05 erg/cm2
and the 1-sec peak flux measured from T+88.71 sec in the 15-150 keV band is
4.8 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.78 +- 0.04 (chi squared 70.95 for 57 d.o.f.).  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/1199764/BA/

N. Higuchi, I. Takahashi, M. Sasada, M. Niwano, S. Sato, S. Hayatsu, H. Takei,  H. Seki, Y. Yatsu and N. Kawai  (Tokyo Tech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 231129A (Gropp et al. GCN 35208
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  and Mereghetti et al. GCN 35209
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 ) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno. 

The observation started at 2023-11-29 08:01:47 UT (2.93 hours after the Swift/BAT and INTEGRAL/IBAS trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the enhanced Swift/XRT error region (Goad et al. GCN 35220
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 ). We obtained the 5-sigma limits of the stacked images as follows.

T0+[hour] | MID-UT | T-EXP[sec] | 5-sigma limits
------------------------------------------------------------------------------------------------
4.50 | 2023-11-29 09:35:41 | 7140 | g'>19.4, Rc>19.0, Ic>18.4
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the trigger
T-EXP: Total Exposure time

We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. 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).

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N. Werner  (Masaryk U.), M. Ohno (Hiroshima U.),  L. Meszaros, B. Csak (Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the VZLUSAT-2/GRB payload collaboration.

The long-duration GRB 231129A (Swift/BAT detection: GCN 35208
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 ; INTEGRAL/IBIS detection: GCN 35209
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 ; GECAM-C detection: GCN 35210
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 ) was detected by the GRB detector on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).

The data acquisition was performed by the GRB detector unit no. 1. The detection was confirmed at the peak time 2023-11-29 05:06:01 UTC. The T90 duration is 157 s and the significance during T90 reaches 21 sigma.

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB231129A_GCN_VZLUSAT2.pdf

All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/
The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.