GRB 241229B

The Fermi GBM team reports the detection of a likely LONG GRB

At 01:36:16 UT on 29 Dec 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 241229B (trigger 757128981.063788 / 241229067).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 275.0, Dec = 62.4 (J2000 degrees, equivalent to J2000 18h 19m, 62d 23'), with a statistical uncertainty of 6.1 degrees.

The angle from the Fermi LAT boresight is 27.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241229067/quicklook/glg_skymap_all_bn241229067.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241229067/quicklook/glg_healpix_all_bn241229067.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241229067/quicklook/glg_lc_medres34_bn241229067.gif

A. D'Ai (INAF-IASFPA), S. Dichiara (PSU), R. Gupta (NASA GSFC),
H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (U Tampa) and
T. M. Parsotan (GSFC) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 01:36:15 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 241229B (trigger=1277428).  Swift did not slew immediately to the burst.
The BAT on-board calculated location is 
RA, Dec 274.149, +74.714 which is 
   RA(J2000) = 18h 16m 36s
   Dec(J2000) = +74d 42' 50"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 10 sec.  The peak count rate
was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger.

Due to an observing constraint, Swift cannot slew to the BAT position.
There will thus be no XRT or UVOT data for this trigger.

Burst Advocate for this burst is A. D'Ai (antonino.dai AT inaf.it).
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/)

V.Lipunov, E.Gorbovskoy, N.Tiurina,  P.Balanutsa, , D.Vlasenko, I.Panchenko,
A.Kuznetsov,  G.Antipov,  A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin,
V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile,  F. Podesta, R.Podesta, E. Gonzalez  (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) 

MASTER-Tunka robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the Swift GRB 241229B ( A. D'Ai et al., GCN 38699
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 ) errorbox  34817 sec after notice time and 34851 sec after trigger time at 2024-12-29 11:17:07 UT, with upper limit up to  19.3 mag. The observations began at zenith distance = 43 deg. The sun  altitude  is -19.1 deg. 

The galactic latitude b = 28 deg., longitude l = 106 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2725189

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   34941 |        MASTER-Tunka |   C |   180 | 19.3 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

We have analysed 2.7 ks of XRT data for GRB 241229B, from 23.5 ks to
34.3 ks after the  BAT trigger. The data are entirely in Photon
Counting (PC) mode. The refined XRT position is RA, Dec = 274.1761,
+74.6833 which is equivalent to:

RA (J2000): 18 16 42.26
Dec(J2000): +74 40 60.0

with an uncertainty of 6.8 arcsec (radius, 90% confidence). The source
has a mean count rate of 1.4e-02 ct/sec; we cannot determine at the
present time whether it is fading.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01277428.

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

T. Komesh (NU), Z. Abdullayev (NU), Z. Maksut (NU), B. Grossan (UCB, NU),  D. Berdikhan (NU), M. Krugov (FAI) and E. Abdikamalov (NU) report on behalf of the Energetic Cosmos Laboratory:

The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) pointed at GRB 241229B on receipt of an automated GCN / BAT position alert, observing in Sloan g' and r' bands, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14).

We started observations at 01:37:16 UT on 2024-12-29, 61 s after the BAT trigger. Observations were made in partly cloudy conditions. No source consistent with the XRT (P.A. Evans et al., GCN Circ. 38708
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 ) was detected. We report the following results:

start time  t-t0(s)    end time    UL g'   UL r'  exposure_time (s)
--------------------------------------------------------------
01:37:16     61 	1:37:41      -     16.67   25
01:38:25     135 	1:40:25    16.21   17.35   120

The start and end time is in UT. t is the middle time, t0 is the BAT trigger time, t-t0 is given in seconds. UL gives the 5 sigma upper limit sensitivity in magnitudes, 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 1 s (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) for r'. The second row corresponds to co-adds from a continuing series of 15 s exposures for g' and r’. Calibration was done with 3 Pan-STARRS catalog stars on our images. No color or other corrections were applied to the values above.

----------------------------------
NU = Nazarbayev University, Astana, Kazakhstan
UCB = University of California, Berkeley, USA
FAI = Fesenkov Astrophysical Institute, Kazakhstan

This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP14870504). 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.

Peter Veres (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 01:36:16.06 UT on 29 December 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 241229B (trigger 757128981/241229067).
which was also detected by Swift BAT (H. A. Krimm et al. 2024, GCN 38699
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 ).
The Fermi GBM on-ground location is consistent with the Swift BAT position.

The angle from the Fermi LAT boresight is 39 degrees.

The GBM light curve consists of a single emission episode with a duration (T90)
of about 6 s (50-300 keV). The time-averaged spectrum
from T0-5.1 to T0+4.1 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.7 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 76 +/- 5 keV.

The event fluence (10-1000 keV) in this time interval is
(1.24 +/- 0.06)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.064 s in the 10-1000 keV band is 6.1 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"

N. P. M. Kuin (UCL-MSSL) and A. D'Ai (INAF-IASFPA SSDC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began observations of the field of GRB 241229B
6.5 hours after the BAT trigger due to an observing constraint
(D'Elia et al., GCN Circ. 38699
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 ).  No optical afterglow
consistent with the XRT position (Evans, GCN Circ. no 38708)
was detected with UVOT.

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

b                23500        39885         1686         >21.5
uvw1             27820        45505         1800         >21.0
u                28727        45738          404         >20.3
uvw2             33481        51179         1800         >21.2
v                34386        51381          376         >20.0
white            39890        40021          132         >20.9
b                55868        56383          254         >20.7

The magnitudes in the table are not corrected for the
Galactic extinction due to the reddening of E(B-V) = 0.06
in the direction of the burst (Schlegel et al. 1998).

S. D. Barthelmy (GSFC), D'Ai (INAF-IASFPA), R. Gupta (GSFC), H. A. Krimm
(NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula
(GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 241229B (trigger #1277428)
(D'Ai et al., GCN Circ. 38699
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 ).  The BAT ground-calculated position is
RA, Dec = 274.140, 74.694 deg which is
   RA(J2000)  =  18h 16m 33.5s
   Dec(J2000) = +74d 41' 39.5"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 39%.

The mask-weighted light curve shows several overlapping pulses that start
at ~T-3 s and end at ~T+3 s. The main peak occurs at ~T+0.5 s, T90 (15-350
keV) is 5.05 +- 0.65 sec (estimated error including systematics).

The time-averaged spectrum from T-2.62 to T+3.38 sec is best fit by a power
law with an exponential cutoff.  This fit gives a photon index 0.93 +-
0.50, and Epeak of 68.3 +- 22.6 keV (chi squared 47.78 for 56 d.o.f.).  For
this model the total fluence in the 15-150 keV band is 7.0 +- 0.6 x 10^-07
erg/cm2 and the 1-sec peak flux measured from T-0.06 sec in the 15-150 keV
band is 4.0 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon
index of 1.70 +- 0.11 (chi squared 55.86 for 57 d.o.f.).  All the quoted
errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1277428

SVOM/VT commissioning team: Y. L. Qiu, H. L. Li (NAOC), A. Li (BNU), Y. F. Liang (PMOC), L. P. Xin, C. Wu, X. H. Han, J. Wang, W. J. Xie, H. B. Cai, Y. Xu, Y. J. Xiao, P. P. Zhang, J. S. Deng, L. Lan, X. M. Lu, R. S. Zhang, Z. H. Yao (NAOC), J. Zhang, L. J. Dan, G. Y. Zou, C. J. Wang, Y. F. Du, C. Huang (XIOPM)

SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC), Olivier Godet (IRAP), Andrea Goldwurm (APC), Diego Götz (CEA), Xu-Hui Han (NAOC), Cyril Lachaud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs.Paris), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Shao-Lin Xiong (IHEP), Bing Zhang (UNLV)

report on behalf of the SVOM team:

The SVOM/VT conducted a ToO follow-up observations of the Fermi (GCN 38698
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 ) and Swift triggered GRB 241229B (GCN 38699
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 ) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously, from 12.09 hours to 15.5 hours after the burst. 

A new optical source was detected within the errorbox of XRT (GCN 38708
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 ) in VT_R stacked image, compared to the PanSTARRS catalog. The brightness of the source was estimated to be 21.8 ± 0.1 mag in AB magnitude in VT_R image at the mid time of 13.8 hours post the burst, with a total exposure time of 34*60 seconds. The source was not detected in VT_B stacked image with 3 sigma upper limit of ~23.2 mag in AB magnitude. 

The source is located at RA, Dec = 274.1803, 74.6851 deg, which is equivalent to:
RA (J2000) : 18:16:43.271
Dec (J2000): +74:41:06.04
with an uncertainty of 0.5 arcsec.

We do not confirm the fading of the source, but which might be the candidate for the gamma-ray burst. 

More deep follow-ups are encouraged for the nature of the source.

The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC),CAS.

A. Volnova (IKI), A. Pozanenko (IKI), V. Rumyantsev (CrAO), N. Pankov (HSE,
IKI) report on behalf of GRB-IKI-FuN collaboration:

We observed the GRB 241229B (Fermi GBM Team, GCN 38698
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 ; D'Ai et al., GCN
38699
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 ) with 2.6-meter ZTSh telescope of CrAO. The observations started on
2024-12-29 (UT) 20:22:02, i.e. ~15.4 hours after GBM trigger.

We clearly detected SVOM/VT optical candidate (SVOM/VT team, GCN 38729
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 ).
The preliminary photometry of the the optical candidate is the following:

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

2024-12-29 20:22:02 0.64631 88x120 R 21.91 0.05 24.2

The magnitudes are calibrated using nearby Pan-Starrs PS1 (transformed into
R by Lupton's transformations)

RA Dec R_Lupton
18:16:50.10 +74:41:42.2 18.928 +- 0.020
18:16:33.99 +74:41:43.6 18.778 +- 0.026
18:16:26.64 +74:41:33.2 17.917 +- 0.014

A. S. Moskvitin, O. I. Spiridonova (SAO RAS), A. A. Volnova and 
A. S. Pozanenko (IKI RAS) report on behalf of the GRB follow-up team.

We observed the field of GRB 241229B (Fermi GBM Team, GCN 38698
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 ; 
D'Ai et al., GCN 38699
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 ) with the 1-m telescope of SAO RAS, Zeiss-1000 
equipped with the CCD-photometer on December 30, 14:47:58--16:04:24 UT,
t_mid - T0 = 1.5763 days. We obtained 12 x 300 sec. images in Rc band.
 
In the stacked image we did not detected OT discovered by SVOM/VT team
(GCN 38729
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 ) and confirmed by Volnova et al., (GCN 38732
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 ) down to the 
limiting magnitude of R_lim = 22.3 (based on the same nearby PS1 stars, 
magnitudes were converted with the Lupton 2005 equations).

SVOM/GRM team: Yue Wang, Chen-Wei Wang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP), 

report on behalf of the SVOM team:

The SVOM/GRM was triggered in-flight by GRB 241229B (SVOM trigger reference: sb24122902) at 2024-12-29T01:36:17.000 UT (T0), which was also observed by Fermi/GBM (Fermi GBM Team, GCN 38698
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 ) and Swift/BAT (A. D'Ai et al, GCN 38699
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 ).

With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of one main pulse  with a T90 of 5.45 +0.76/-1.01 s

This burst is located (from Swift/BAT) at about 57.10 degrees from the SVOM optical axis, and outside the ECLAIRs field of view.

The GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb241229B.png

The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS.

The SVOM point of contact for this burst is: Yue Wang (IHEP)(yuewang@ihep.ac.cn)

N. Pankov (HSE, IKI),  A. Volnova (IKI),  A. Pozanenko (IKI), V. Rumyantsev
(CrAO),  report on behalf of the IKI-GRB-FuN collaboration:

We observed the field of GRB 241229B (Fermi GBM Team, GCN 38698
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 ; D'Ai et
al., GCN 38699
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 ) with 2.6-meter ZTSh telescope of CrAO. The observations
started on 2024-12-30 (UT) 18:30, i.e. ~1.73 days since GBM trigger. The
series of 30x120 s images were obtained using the CCD-photometer. The
optical counterpart (SVOM/VT team, GCN 38729
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 ; Volnova et. al, GCN 38732
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 )
has been detected in a stacked image. Preliminary photometry is the
following:

Date        UTstart T-T0        Exp.   Filter OT   Err.  UL(3sigma)
          (mid, days) (s)

2024-12-30 18:13:33 1.73423     30x120 R      23.40 0.15 24.0

The photometry has been calibrated against nearby PS1 stars (see Volnova
et. al, GCN 38732
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 ).