GRB 241209D

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

At 10:59:44 UT on 9 Dec 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 241209D (trigger 755434789.093062 / 241209458).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 191.7, Dec = -2.2 (J2000 degrees, equivalent to J2000 12h 46m, -2d 12'), with a statistical uncertainty of 1.9 degrees.

The angle from the Fermi LAT boresight is 80.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241209458/quicklook/glg_skymap_all_bn241209458.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/bn241209458/quicklook/glg_healpix_all_bn241209458.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241209458/quicklook/glg_lc_medres34_bn241209458.gif

T. M. Parsotan (GSFC), E. Ambrosi (INAF-IASFPA),
A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC & INAF-OAR),
J. J. DeLaunay (PSU), P. A. Evans (U Leicester),
R. A. J. Eyles-Ferris (U Leicester) and A. Melandri (INAF-OAR) report
on behalf of the Neil Gehrels Swift Observatory Team:

At 10:59:46 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 241209D (trigger=1273106).  Swift slewed immediately to the burst.
The BAT on-board calculated location is 
RA, Dec 190.111, -2.879 which is 
   RA(J2000) = 12h 40m 27s
   Dec(J2000) = -02d 52' 42"
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 150 sec.  The peak count rate
was ~3200 counts/sec (15-350 keV), at ~0 sec after the trigger.

The XRT began observing the field at 11:01:20.0 UT, 93.6 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 190.1129, -2.8901 which is equivalent to:
   RA(J2000)  = 12h 40m 27.09s
   Dec(J2000) = -02d 53' 24.5"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 41 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy.

The initial visibility window of the GRB was very short and no prompt
UVOT data were generated. We await the full dataset to search for any
UV/optical afterglow.

Burst Advocate for this burst is T. M. Parsotan (tyler.parsotan AT nasa.gov).
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/)

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

Using 1140 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 241209D, 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 = 190.11190, -2.89162 which is equivalent
to:

RA (J2000): 12h 40m 26.86s
Dec (J2000): -02d 53' 29.8"

with an uncertainty of 2.8 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.

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 241209D ( T. M. Parsotan et al., GCN 38489
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 ) errorbox  33929 sec after notice time and 33951 sec after trigger time at 2024-12-09 20:25:37 UT, with upper limit up to  18.8 mag. The observations began at zenith distance = 75 deg. The sun  altitude  is -41.5 deg. 

The galactic latitude b = 60 deg., longitude l = 299 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2701233

We obtain a following upper limits.  

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

   34041 |        MASTER-Tunka |   C |   180 | 15.0 |        
   35265 |        MASTER-Tunka |   C |   180 | 18.8 |        
Filter C is a clear (unfiltred) band. 


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

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) started inspect of the Fermi GRB 241209D ( Fermi GBM team, GCN 38488
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 ) errorbox  33914 sec after notice time and 33953 sec after trigger time at 2024-12-09 20:25:37 UT, with upper limit up to  19.2 mag. The observations began at zenith distance = 75 deg. The sun  altitude  is -41.5 deg. 

The galactic latitude b = 60 deg., longitude l = 302 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2701308

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   34044 | 2024-12-09 20:25:37 |        MASTER-Tunka | (12h 40m 42.72s , -02d 49m 30.7s) |   C |   180 | 15.0 |        
   34224 | 2024-12-09 20:25:37 |        MASTER-Tunka | (12h 40m 42.76s , -02d 49m 32.4s) |   C |   540 | 19.2 |  Coadd 
   35267 | 2024-12-09 20:46:01 |        MASTER-Tunka | (12h 40m 48.04s , -02d 50m 25.9s) |   C |   180 | 18.8 |        
   36758 | 2024-12-09 21:10:52 |        MASTER-Tunka | (12h 40m 47.42s , -02d 47m 55.6s) |   C |   180 | 19.0 |        
   37967 | 2024-12-09 21:31:01 |        MASTER-Tunka | (12h 40m 42.47s , -02d 48m 50.9s) |   C |   180 | 19.3 |        
Filter C is a clear (unfiltred) band. 


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

J.-G. Ducoin (CPPM), Francesco Magnani (CPPM), Damien Dornic (CPPM), Alan M. Watson (UNAM), Margarita Pereyra (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), S. Antier (OCA), Jean-Luc Atteia (IRAP), Nathaniel R. Butler (ASU), Francis Fortin (IRAP), Dahlia Alk (AUS) and Simona Lombardo (LAM), report:

We imaged the field of GRB 241209D detected by Swift/BAT and Fermi/GBM (GCN Circ. 38488
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 , 38489
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 , 38491
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 ) during the commissioning of the COLIBRÍ (SVOM/F-GFT) telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico.

The observations started 21 minutes after the GRB trigger. We observed with the engineering test camera in a red filter that approximates SDSS r. The data were reduced using custom software and then analysed and calibrated against the PS1 catalog using the STDWeb service (Karpov et al. 2022).

In 4260 seconds of exposure from 2024/12/09 11:20:50 (UT) to 12:59:15, we detect the optical counterpart with:

    r = 20.04 +/-0.05 (SNR ~21.6)

This source is right next to a catalogued galaxy in PAN-STARRs with rmag of ~21.44. Given the significant difference in magnitude and the slight visible offset with the PAN-STARRs object position, we consider this to be the Afterglow of GRB 241209D.

We warmly thank the COLIBRI engineering team and the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir. We warmly thank the GRANDMA IJCLAB team and S. Karpov for the access of the STDWeb service for STDPipe.

C. Malacaria (INAF-OAR) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 10:59:44.09 UT on 09 December 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 241209D (trigger 755434789/241209458).
which was also detected by Swift BAT (T. M. Parsotan et al. 2024, GCN 38489
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 , 
M.R. Goad et al. 2024, GCN 38491
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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 82 degrees.

The GBM light curve consists of a single emission episode with a duration (T90)
of about 45 s (50-300 keV). The time-averaged spectrum
from T0-0.8 to T0+44.3 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.40 +/- 0.07 and the cutoff energy,
parameterized as Epeak, is 110 +/- 3 keV.

The event fluence (10-1000 keV) in this time interval is
(9.5 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+5.9 s in the 10-1000 keV band is 4.4 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 107 +/- 4 keV, alpha = -0.35 +/- 0.08 and beta = -3.4 +/- 0.6.

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/"

K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi 
(INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR),
S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU) and P.A. Evans
report on behalf of the Swift-XRT team:

We have analysed 6.4 ks of XRT data for GRB 241209D, from 260 s to 37.7
ks after the  BAT trigger. The data comprise 22 s in Windowed Timing
(WT) mode with the remainder in Photon Counting (PC) mode. 

The light curve can be modelled with an initial power-law decay with an
index of alpha=4.3 (+3.4, -2.5), followed by a break at T+626 s to an
alpha of 0.66 (+/-0.13).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.89 (+0.29, -0.26). The
best-fitting absorption column is  5.9 (+6.9, -3.6) x 10^20 cm^-2,
consistent with 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 3.5 x 10^-11 (4.0 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     5.9 (+6.9, -3.6) x 10^20 cm^-2
Galactic foreground: 2.3 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.89 (+0.29, -0.26)

If the light curve continues to decay with a power-law decay index of
0.66, 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 5.1 x
10^-13 (5.8 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/01273106.

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

M. Tembhurnikar (IUCAA), G. Waratkar (IITB), A. Dasgupta (BITS Pilani, Hyderabad), J. Joshi (IUCAA), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long-duration GRB 241209D which was also detected by Fermi/GBM (Fermi-GBM Team, GCN Circ. 38507
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 ), and Swift/BAT (Page et al., GCN Circ. 38508
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 ).

The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-12-09 10:59:47.1 UTC. The measured peak count rate associated with the burst is 739 (+62, -67) counts/s above the background in the combined data of all quadrants, with a total of 9569 (+1176, -1291) counts. The local mean background count rate was 6618 (+7, -8) counts/s. We measure a T90 of 26 (+5, -6) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb

A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
A. Tsvetkova,  M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:

The long-duration GRB 241209D
(Fermi-GBM detection: Fermi GBM team, GCN 38488
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 ;
Malacaria & Meegan, GCN 38507
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 ;
Swift-BAT detection: Parsotan et al., GCN 38489
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 ;
AstroSat CZTI detection: Tembhurnikar et al., GCN 38518
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 )
was detected by Konus-Wind (KW) in the waiting mode.

A Bayesian block analysis of the KW waiting mode data in the 20-300 keV band
reveals a >13 sigma count rate increase in the interval
from T0-2.0 s to T0+42.160 s where T0 = T0(BAT) = 10:59:45.649 UT.

The KW light curve of this burst is available at
http://www.ioffe.ru/LEA/GRBs/GRB241209D/

Modeling a time-integrated spectrum of the burst
(from T0-2.0 s to T0+42.160 s)
by a power law with exponential cutoff (CPL) model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep):
yields alpha = -1.16 (-0.37, +4.03) and Ep = 90(-12,+14) keV.

The total burst fluence is 8.79(-0.87,+1.74)x10^-6 erg/cm^2,
and the 2.944 s peak energy flux, measured from T0-2.0 s,
is 5.86(-0.75,+1.25)x10^-7 erg/cm^2.
(both in the 20 keV - 10 MeV energy range).

All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.

R.Brivio, M. Ferro, P. D’Avanzo, Y.-D. Hu, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team:

We observed the field of GRB 241209D detected by Swift/BAT (Parsotan et al., GCN 38489
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 ) and Fermi/GBM (Fermi GBM team, GCN 38488
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 ) with the REM 60cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, J, H, K bands, starting on 2024 December 10 at 06:54:39 UT (i.e. 19.9 hours after the Swift trigger), and lasting for about 1 hour.

From preliminary photometry we do not detect the optical counterpart (Ducoin et al., GCN 38505
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 ) in the optical and NIR images at the Swift-XRT enhanced position (Goad et al., GCN 38491
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 ) down to the following 3sigma magnitude upper limits:

r > 20.3 (AB; calibrated against the PanSTARRS catalogue)
at a mid-time of t - t0 = 20.4 hr after the trigger,

J > 18.1 (Vega; calibrated against the 2MASS catalogue) 
at a mid-time of t - t0 = 20.5 hr after the trigger.

A. Yoshida, T. Sakamoto, S. Sugita, Y. Kawakubo (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), 
S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu, 
T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), 
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 241209D (Fermi GBM Final Real-time Localization: 
Fermi GBM team, GCN Circ 38488
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 ; Swift detection of a burst: 
Parsotan et al., GCN Circ 38489
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 ; Fermi GBM Observation: Malacaria
et al., GCN Circ 38507
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 ; AstroSat CZTI detection: Tembhurnikar et al.,
GCN Circ 38518
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 ; Konus-Wind detection: Ridnaia et al., GCN Circ 
38526
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 ) triggered the CALET Gamma-ray Burst Monitor (CGBM) at
10:59:46.760 UTC on 9 December 2024
(https://cgbm.calet.jp/cgbm_trigger/flight/1417777157/index.html).
The burst signal was seen by only the SGM detector.  Because of a
problem with the ground alert processing script, the GCN notice was
not distributed automatically for this event.

The burst light curve shows a single pulse that starts at T-4.0 sec, 
peaks at T+0.6 sec, and ends at T+6.7 sec. The T90 and T50 durations
measured by the SGM data are 9.2 +/- 0.7 sec and 4.6 +/- 0.4 
sec (40-1000 keV), respectively.

The ground-processed light curve is available at

https://cgbm.calet.jp/cgbm_trigger/ground/1417777157/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.

M. Dafcikova, J. Ripa, M. Kolar (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Duriskova, L. Szakszonova, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal,  A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.

The long-duration GRB 241209D (Fermi/GBM detection: GCN 38488
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 ; Swift/BAT detection: GCN 38489
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 ; AstroSat/CZTI detection: GCN 38518
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 ; Konus/Wind detection: GCN 38526
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 ; CALET/CGBM detection: GCN 38569
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 ) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui.adsabs.harvard.edu/abs/2023A%26A...677A..40P/abstract).

The detection was confirmed at the peak time 2024-12-09 10:59:45.2 UTC. The T90 duration measured by GRBAlpha is 52 s and the overall significance during T90 reaches 11 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB241209D_GCN.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume.