Skip to main content
Due to the lapse in federal government funding, NASA is not updating this website. See the Operations FAQ for GCN impacts.
New! Super-Kamiokande JSON Notices and Schema v4.5.0. See news and announcements

GRB 250129A

GCN Circular 39246

Subject
GRB 250129A: GRANDMA Continued Afterglow Detection
Date
2025-02-09T07:57:22Z (8 months ago)
Edited On
2025-02-10T14:10:06Z (8 months ago)
From
Sarah Antier at OCA <sarah.antier@oca.eu>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Dalya Akl at American Uni. SHJ <dalyaakl.d@gmail.com>
Via
Web form
D. Akl (AUS), S. Antier (OCA/IJCLAB), M. Tanasan (NARIT). A. Simon (TShNU of Kyiv), N. Sasaki (OPD/LNA), S. Karpov (FZU), D. Turpin (CEA-Saclay/Irfu), M. Coughlin (UMN), P. Hello (IJCLAB), C. Andrade (UMN), P-A Duverne (APC), T. Pradier (Unistra/IPHC), I. Tosta e Melo (UniCT-DFA), N. Guessoum (AUS), A. Takey (NRIAG), Y. Hendy (NRIAG), M. Abdelkareem (NRIAG), E. Elhosseiny (NRIAG), N. Kochiashvili (AbAO), V. Zhuzhunadze (AbAO), V.Aivazyan (AbAO), R. Inasaridze (AbAO), A. Klotz (IRAP), F. Colas (Obs-Paris/LTE), A. Iskandar（XAO), X. F. Wang (THU), R. Hellot (KNC, AITP-OBS-SPC), M. Freeberg (KNC), S. Leonini (KNC, Montarrenti Obs.), C. Galdies (KNC), D. Marchais (KNC), M. Odeh (KNC, AKO), B. M. Mihov (BAS), L. Slavcheva-Mihova (BAS), T. Sun (PMO), F. Dux (Euler),
on behalf of GRANDMA:

We observed the field of GRB 250129A detected by Swift (Beardmore et al., GCN 39066) using GRANDMA and its citizen science project Kilonova-catcher (KNC).

We clearly detect the optical afterglow  and we report a subset of  the following magnitudes using different instruments:

| T-T0 (d)|Filter| Magnitude (AB) |Exposure(s)| Telescope    | 
| 0.65    | g'   | 19.21 +/- 0.03 | 10x100s   | TNOT         |
| 0.86    | i'   | 18.92 +/- 0.03 | 5x150s    | KAO          | 
| 2.77    | R    | 20.19 +/- 0.08 | 50x60s    | AbAO-T70     |
| 3.04    | V    | 20.35 +/- 0.04 | 3x600s    | KNC          |
| 4.88    | g'   | 21.12 +/- 0.06 | 10x600s   | NAO-2m       |
| 6.99    | r'   | 22.8 +/- 0.14  | 20x180s   | 1m-PicduMidi |

All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained in Johnson Cousin filters were calibrated using the Gaia DR3 Synphot catalog, images taken with Sloan filters were calibrated with PanSTARRS-DR1 Catalog. Our measurements are not corrected from extinction. Weather conditions were excellent in all sites.

We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023).

GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).

GCN Circular 39213

Subject
GRB 250129A: ABObservatory SLOAN r’ afterglow detection
Date
2025-02-07T18:49:05Z (8 months ago)
From
A. Brosio at ABObservatory Rosarno <antonino.brosio@gmail.com>
Via
Web form
A. Brosio (ABObservatory), S. Savaglio (University of Calabria), S. Tosi, S. Zappatore & P. Cianfarra (University of Genoa), S. Benatti (INAF Palermo), M. Rainer (INAF Brera), D. Ricci (INAF Padova), A. Di Dato (INAF Capodimonte), S. Masiero & A. Nastasi (GAL Hassin), L. Betti (Osservatorio Polifunzionale del Chianti), D. Liguori (Osservatorio “G. Galilei” Cariati)  for the NOCTIS team report:

We observed the field of GRB 250129A, which was detected by Swift (Beardmore et al., GCN 39066) with the 30-cm automated telescope at ABObservatory (Rosarno, Italy) using the SLOAN r’ filter. Observations began on 2025 January 30 at 23:41:31 UT, approximately 43 hours after the Swift trigger. The observation consisted of 10 exposures of 240 seconds each, with variable conditions due to passing clouds during the session. The mid-exposure time was 00:07:31 UT, and the final exposure ended at 00:33:31 UT.

From photometry, we detect the optical counterpart in our images at the position of the previously reported afterglow (Francile et al., GCN 39065; Schneider et al., GCN 39071; Belkin et al., GCN 39072; Izzo et al., GCN 39073; Izzo & Malesani, GCN 39074; Gosh et al., GCN 39077; Schneider et al., GCN 39078).

The measured magnitude is:

r’ = 19.32 +/- 0.13 (AB, calibrated against the Pan-STARRS catalogue on SIMBAD)
at a mid-time of t - t0 = 00:12:43 after the trigger.

GCN Circular 39192

Subject
GRB 250129A: Continued AbAO and Mondy optical observations
Date
2025-02-07T06:03:52Z (8 months ago)
From
Nicolai Pankov at HSE, IKI RAS <colinsergesen@gmail.com>
Via
Web form
N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP), R. Ya. Inasaridze (AbAO) report on behalf of the IKI-GRB-FuN collaboration:

We continued optical observations of the field of GRB 250129A (Beardmore et. al, GCN 39066; Lipunov et. al, GCN 39070; Schneider et. al, GCN 39071; Belkin et. al, GCN 39072; Izzo et. al, GCN 39073; Izzo et. al, GCN 39074; Ghosh et. al, GCN 39077; Schneider et. al, GCN 39078; Brivio et. al, GCN 39079; Goad et. al, GCN 39082; Siegel, GCN 39085; Osborne et. al, GCN 39089; Zheng et. al, GCN 39090; Schlekat et. al, GCN 39091; Antier et. al, GCN 39096; Odeh et. al, GCN 39097; Ferro et. al, GCN 39098; Malesani et. al, GCN 39100; Romanov, GCN 39101; Zheng et. al, GCN 39102; Watson et. al, GCN 39104; Watson et. al, GCN 39105; Akl et. al, GCN 39106; Moskvitin et. al, GCN 39107; Calapai et. al, GCN 39109; Schlekat et. al, GCN 39110; Gompertz et. al, GCN 39114; Ror et. al, GCN 39115; Frederiks et. al, GCN 39116; Wu et. al, GCN 39124; Paek et. al, GCN 39129; Moskvitin et. al, GCN 39130; Bochenek et. al, GCN 39131; Watson et. al, GCN 39136; Pankov et. al, GCN 39139; Pérez-Fournon et. al, GCN 39140; Markwardt et. al, GCN 39147) in the R filter with the 1.5-meter AZT-33IK telescope of the Sayan Solar Observatory (Mondy) and the 0.7-meter AS-32 telescope of the Abastumani Observatory (AbAO). The observations began at Mondy on 2025-02-02 at 19:46:28 UT, i.e. ~4.65 days since trigger. Using optimal image subtraction against PS1 template with apex_subtract pipeline, we detect the optical counterpart in the stacked image from Mondy, while obtaining an upper limit at AbAO. The preliminary photometry is as follows:

Date       UT start  t-T0         Exp.    Filter   OT        Err.       UL(3sigma) Telescope
                     (mid, days)  (s)
2025-02-02 19:46:28  4.65439      41*120  R        21.63     0.18       23.1       AZT-33IK
2025-02-02 22:26:20  4.76923      93*60   R        n/d       n/d        21.8       AS-32


The photometry is based on nearby stars of the USNO-B1.0 catalog (R2 magnitudes) and has not been corrected for the Galactic extinction.

GCN Circular 39147

Subject
GRB 250129A: Swift-BAT refined analysis
Date
2025-02-04T20:36:28Z (8 months ago)
From
Rahul Gupta at NASA GSFC <rahul.gupta@nasa.gov>
Via
Web form
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), 
A. P. Beardmore (U Leicester), R. Gupta (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC), 
A. Y. Lien (U Tampa), 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-571 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 250129A (trigger #1285812)
(Beardmore, et al., GCN Circ. 39066).  The BAT ground-calculated position is
RA, Dec = 198.708, 5.029 deg which is 
   RA(J2000)  =  13h 14m 49.8s 
   Dec(J2000) = +05d 01' 44.9" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 84%.
 
The mask-weighted BAT light curve exhibits a multi-peaked and complex structure, with the most prominent peak occurring at approximately T0 + 184 seconds. T90 (15-350 keV) is 262.25 +- 23.71 sec (estimated error including systematics).
 
The time-averaged spectrum from T-64.39 to T+302.62 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.17 +- 0.09.  The fluence in the 15-150 keV band is 5.0 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+184.12 sec in the 15-150 keV band
is 1.4 +- 0.2 ph/cm2/sec.  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/1285812

GCN Circular 39140

Subject
GRB 250129A: LCO late afterglow detection
Date
2025-02-04T11:47:57Z (8 months ago)
From
Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf@iac.es>
Via
Web form
I. Pérez-Fournon (IAC and ULL), F. Poidevin (IAC and ULL), D. Cano-Morales (ULL), I. Correa-Plasencia (ULL), and A.E. Hernández-Díaz (ULL)

We observed the field of the Swift GRB 250129A (Beardmore et al., GCN Circ. 39066) with one of the Las Cumbres Observatory Global Telescope network (LCOGT) 1-m telescopes equipped with a Sinistro camera at the LCOGT node at the Cerro Tololo Inter-American Observatory (Chile). We obtained a single 300-sec image in the SDSS-r' filter starting at 2025-02-03 07:35:39 UT, approximately 5.118 days after the trigger.

The optical transient detected by Swift UVOT (Beardmore et al., GCN Circ. 39066) is clearly detected with a magnitude of r' = 22.04 +/- 0.21, calibrated against PanSTARRS stars and not corrected for extinction. 

The optical brightness of the afterglow is consistent with the results of late-time observations by Bochenek and Perley (GCN Circ. 39131) and Watson et al. (GCN Circ. 39136).
 

This work makes use of observations from the Las Cumbres Observatory global telescope network (LCOGT observing programme IAC2025A-009, SGLF).

GCN Circular 39139

Subject
GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
Date
2025-02-04T07:44:31Z (8 months ago)
From
Nicolai Pankov at HSE, IKI RAS <colinsergesen@gmail.com>
Via
Web form
N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP), R. Ya. Inasaridze (AbAO) report on behalf of the IKI-GRB-FuN collaboration:

We performed optical observations of the field of GRB 250129A (Beardmore et. al, GCN 39066; Lipunov et. al, GCN 39070; Schneider et. al, GCN 39071; Belkin et. al, GCN 39072; Izzo et. al, GCN 39073; Izzo et. al, GCN 39074; Ghosh et. al, GCN 39077; Schneider et. al, GCN 39078; Brivio et. al, GCN 39079; Goad et. al, GCN 39082; Siegel, GCN 39085; Osborne et. al, GCN 39089; Zheng et. al, GCN 39090; Schlekat et. al, GCN 39091; Antier et. al, GCN 39096; Odeh et. al, GCN 39097; Ferro et. al, GCN 39098; Malesani et. al, GCN 39100; Romanov, GCN 39101; Zheng et. al, GCN 39102; Watson et. al, GCN 39104; Watson et. al, GCN 39105; Akl et. al, GCN 39106; Moskvitin et. al, GCN 39107; Calapai et. al, GCN 39109; Schlekat et. al, GCN 39110; Gompertz et. al, GCN 39114; Ror et. al, GCN 39115; Frederiks et. al, GCN 39116; Wu et. al, GCN 39124; Paek et. al, GCN 39129) in the R filter with the 1.5-meter AZT-33IK telescope of the Sayan Solar Observatory (Mondy) and the 0.7-meter AS-32 telescope of the Abastumani Observatory (AbAO). The observations began on 2025-01-30 at 22:16:50 UT, i.e. ~1.76 days since trigger. The optical counterpart is well detected in the stacked images from both observatories. The preliminary photometry is as follows:

Date       UT start  t-T0         Exp.    Filter   OT        Err.       UL(3sigma) Telescope
                     (mid, days)  (s)
2025-01-30 22:16:50  1.76610      103*60  R        19.46     0.21       22.0         AS-32
2025-01-31 19:38:51  2.65188      45*120  R        20.38     0.08       23.0         AZT-33IK
2025-02-01 19:32:02  3.64507      42*120  R        20.82     0.11       22.9         AZT-33IK

The photometry is based on nearby stars of the USNO-B1.0 catalog (R2 magnitudes) and have not been corrected for the Galactic extinction.

GCN Circular 39136

Subject
GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
Date
2025-02-03T20:10:36Z (8 months ago)
From
Alan Watson at UNAM <alan@astro.unam.mx>
Via
email
Alan M. Watson (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah
Antier (OCA), Rosa L. Becerra (Università degli Studi di Roma Tor
Vergata), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc
Atteia (IRAP), Nathaniel R. Butler (ASU), Damien Dornic (CPPM),
Francis Fortin (IRAP), Jean-Grégoire Ducoin (CPPM), Francesco Magnani
(CPPM), Margarita Pereyra (UNAM), Benjamin Schneider (LAM)

and the DDRAGO engineering team:

Luis Carlos Álvarez (UNAM), Fernando Angeles, Salvador Cuevas (UNAM),
François Dolon (OHP), Alejandro Farah (UNAM), Johan Floriot (LAM),
Jorge Fuentes-Fernández (UNAM), Arthur Langios (IRAP), Rosalía
Langarica (UNAM), Simona Lombarda (LAM), Jaime Ruíz Díaz-Soto (UNAM),
Samuel Ronayette (CEA), Silvio Tinoco (UNAM), and Hervé Valentín
(IRAP)

report:

We imaged the field of the Swift GRB 250129A (Beardmore et al., GCN
Circ. 39066) with the COLIBRÍ (SVOM/F-GFT) telescope at the
Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in
Mexico.

We observed with the DDRAGO wide-field science camera (Langarica et
al., 2024, Proc SPIE 13096, 130963D) in a filter that closely
approximates Pan-STARRS r, from 2025-02-03 07:45 to 08:00 UTC, at a
midpoint of 5.20 days after the event, and obtained 600 seconds of
exposure at a median airmass of 2.25 and good weather conditions. The
data were reduced using custom software and then analysed and
calibrated against the PS1 catalog using STDPipe (Karpov 2021).

We clearly detect the afterglow with

r = 22.10 +/- 0.15

This magnitude is not corrected for Galactic extinction. Our
measurement is consistent with the magnitude reported by Bochenek &
Perley (GCN Circ. 39131) at 4.93 days after the event.

Further observations are planned.

The DDRAGO camera is still being commissioned, and these are its first
science observations. We warmly thank the COLIBRÍ engineering team and
the staff of the Observatorio Astronómico Nacional on the Sierra de
San Pedro Mártir.

GCN Circular 39131

Subject
GRB 250129a: Liverpool Telescope optical follow-up
Date
2025-02-03T14:47:32Z (8 months ago)
From
A. Bochenek at Liverpool John Moores University <a.m.bochenek@2023.ljmu.ac.uk>
Via
Web form
A. Bochenek and D. A. Perley (LJMU) report:

We observed the field of GRB250129a (Beardmore et al., GCN 39066) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 10x90s exposures in the SDSS r’ filter starting at 2025-02-02 02:53:56 UT, approximately 4.93 days after the trigger.

We report a detection of the optical transient (Beardmore et al., GCN 39066) in the stacked images of r = 21.80 ± 0.11 mag.  Our detection is consistent with other late-time observations (Schlekat et al., GCN39110, Gompertz et al., GCN 39114, Moskvitin et al., GCN39130), and suggests the afterglow is now decaying faster, with a temporal index of approx. -2.2 (fit to observations after 2.5 days post-trigger).

The photometry was obtained using nearby PanSTARRS standards and was not corrected for extinction.

GCN Circular 39129

Subject
GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
Date
2025-02-03T06:14:53Z (8 months ago)
From
Gregory Paek at Seoul National University <gregorypaek94@gmail.com>
Via
Web form
Gregory S.H. Paek (IfA, SNU ARC/SNU), Myungshin Im (SNU ARC/SNU), Hyeonho Choi (SNU ARC/SNU), Donggeun Tak (SNU ARC/SNU), Seo-Won Chang (SNU ARC/SNU), and Ji Hoon Kim (SNU ARC/SNU) report on behalf of the 7-Dimensional Telescope collaboration

We detected the optical counterpart of GRB 250129A using the 7-Dimensional Telescopes (7DT). Approximately 1 hour and 14 minutes following the initial detection by Swift (Swift team, Beardmore et al., GCN #39066), we targeted the localization center provided by Swift/UVOT at RA, Dec = 198.67673 deg, +5.03063 deg with an uncertainty of 1.10 arcseconds. Observations were made with eleven 7DT units in r-band and nineteen medium-band filters, denoted as m400, m425, then through m875, in which the numeric values indicate their central wavelengths in nanometers. Each medium-band filter has a bandwidth of 25nm.

Photometric flux calibration was performed using synthetic photometry based on the Gaia DR3 XP catalog (Gaia Collaboration et al. 2022) within the AB magnitude system. The optical counterpart was detected in most filters. However, only marginal detection was observed in m800, m825, m850, and m875. This is based on preliminary photometry, and no extinction correction has been applied. The 5-sigma upper limits (AB) and detections in relevant filters are summarized below.
------
Filter Mag  Mag_err Date-obs[UT]        Exp.time[s] Depth(5sigma) Note
m425   17.3 0.0     2025-01-29T05:59:21 300         19.9
m450   17.2 0.0     2025-01-29T05:53:51 300         19.2
m475   17.2 0.0     2025-01-29T05:59:21 300         19.5
m500   17.2 0.0     2025-01-29T05:53:51 300         20.0
m525   17.2 0.0     2025-01-29T05:59:20 300         20.1
m550   17.0 0.1     2025-01-29T05:53:52 300         18.6
m575   17.0 0.0     2025-01-29T05:59:19 300         18.8
m600   16.9 0.0     2025-01-29T05:53:58 300         19.7
m625   16.9 0.0     2025-01-29T05:59:36 300         19.4
m650   16.9 0.0     2025-01-29T05:53:56 300         19.4
m675   17.1 0.1     2025-01-29T05:59:22 300         19.4
m700   16.9 0.0     2025-01-29T05:53:49 300         19.2
m725   17.0 0.0     2025-01-29T05:59:17 300         18.9
m750   17.0 0.1     2025-01-29T05:53:54 300         18.8
m775   17.0 0.1     2025-01-29T05:59:22 300         18.3
m800                2025-01-29T05:53:59 300         17.8          n/d
m825                2025-01-29T05:59:32 300         17.6          n/d
m850                2025-01-29T05:53:54 300         17.2          n/d
m875                2025-01-29T05:59:15 300         17.1          n/d
r      17.0 0.0     2025-01-29T05:59:07 600         20.9

The 7-Dimensional Telescope (7DT), located in Chile and comprising 20 wide-field telescopes equipped with 40 medium-bandwidth (~25nm) filters, aims to detect optical counterparts of GW sources and conduct the 7-Dimensional Sky Survey (7DS) of the Southern Hemisphere. Further information about the 7DT is available at http://gwuniverse.snu.ac.kr/.

GCN Circular 39124

Subject
GRB 250129A: SVOM/C-GFT optical observations
Date
2025-02-02T11:25:12Z (8 months ago)
From
Chao Wu at NAOC <cwu@nao.cas.cn>
Via
Web form
Chao WU (NAOC), Zhe Kang (CHO), Liping Xin(NAOC), Xuhui Han(NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao(NAOC), Yulei, Qiu(NAOC), Jing Wang(NAOC), Jianyan Wei (NAOC) report on behalf of the SVOM/C-GFT team:


We observed the field of GRB 250129A detected by Swift/BAT (Beardmore et al., GCN 39066) with C-GFT. Our observations were started on 2025-01-30T17:51:44 UTC, ~37.11 hr after the trigger. A series of g, r and i band images were obtained with exposure time of 30s for each image. The optical counterpart (Beardmore et al., GCN 39066; Francile et al., GCN 39065; Lipunov et al., GCN 39070; Schneider et al., GCN 39071; Belkin et al., GCN 39072; Izzo et al., GCN 39073; Izzo et al., GCN 39074; Francile et al., GCN 39075; Ghosh et al., GCN 39077; Schneider et al., GCN 39078; Brivio et al.,GCN 39079; Siegel et al.,GCN 39085; Zheng et al., GCN 39090; Schlekat et al., GCN39091; Antier et al., GCN 39096; Odeh et al. GCN 39097; Ferroet al. GCN 39098; Bochenek et al., GCN 39099; Malesani et al., GCN 39100; Romanov et al., GCN 39101; Zheng et al., GCN 39102; Watson et al., GCN 39104;Vinko et al., GCN 39105; Akl et al., GCN 39106; Moskvitin et al., GCN 39107; Giovanni et al., GCN 39109; Schlekat et al., GCN 39110; Schlekat et al., GCN 39114 and Ror et al., GCN 39115) was clearly detected in stacked images of band g,r and i. The results are,

(T-T0)_mid(hr)   mag  mag_err  band
-----------------------------------------
    37.73       20.08   0.22    g
    37.83       19.74   0.16    r
    37.92       19.32   0.11    i

The photometry was calibrated with nearby Pan-STARRS1 stars.

We thank the observation assistants Bowen Li and Yinghuai Hao at Jilin observatory for their excellent support.


Chinese Ground Follow-up Telescope of SVOM mission is located at Jilin, Changchun Observatory, National Astronomical Observatories, CAS. It has FOV of 1.28 deg x 1.28 deg with a 4k*4k CMOS detector mounted on the primary focus of 1.2-meter-aperure telescope.

GCN Circular 39119

Subject
Swift GRB250129A: MASTER 4 days observations report
Date
2025-02-02T03:23:05Z (8 months ago)
Edited On
2025-02-02T14:39:22Z (8 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Vladimir Lipunov at Lomonosov Moscow State University <lipunov@sai.msu.ru>
Via
email

V.Lipunov, E.Gorbovskoy, A.Kuznetsov, N.Tiurina,  P.Balanutsa, I.Panchenko, K.Zhirkov, G.Antipov,  A.Sankovich, A.Sosnovskij, Yu.Tselik, Ya.Kechin, V.Senik, V.Topolev, A.Chasovnikov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile,  F. Podesta, R.Podesta, E. Gonzalez  (Observatorio Astronomico Felix Aguilar (OAFA),
D.Buckley (SAAO),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),
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)


The MASTER-OAFA All Sky Camera   located in Argentina (OAFA observatory of San Juan National University) imaged
SWIFT GRB 250129A (A. P. Beardmore et al., GCN 39066) errorbox
 with upper limit up to  ~8 mag (V) at single 5-s images with _prompt_ limit  ~10 mag.

MASTER-OAFA Very Wide Field Camera (VWFC,  MASTER-ShOK camera of  Global MASTER-Net: http://observ.pereplet.ru,
Lipunov, Korniov, Gorbovskoy, Tiurina & Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 626 pp.)
located in Argentina (OAFA observatory of San Juan National  University)
was pointed to the SWIFT GRB 250129A ( A. P. Beardmore et al., GCN 39066) errorbox 185  sec after trigger time at 2025-01-29 04:48:14 UT, with upper limit up to  ~15  mag.

MASTER500-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru)  located in Argentina (OAFA observatory of San Juan National University)
was pointed to the SWIFT GRB 250129A (Francile et al., GCN 39065) errorbox  160 sec after notice time (240sec after trigger time)
at 2025-01-29 04:49:09 UT, with upper limit up to  21.1 mag.

 The observations began at zenith distance = 73 deg. (the sun  altitude  was -41.0 deg.) and were continued at 30, 31 Jan, 01, 02 Feb.


MASTER600-Tunka robotic telescope  located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the SWIFT GRB 250129A errorbox  40114 sec after notice time (40194 sec after trigger time) at 2025-01-29 15:55:03 UT, with upper limit up to  21.0 mag.
The observations began at zenith distance = 85 deg (the sun  altitude  was -52.8 deg.) and were continued at 30, 31 Jan, 01, 02 Feb 2025.


MASTER-Kislovodsk robotic telescope  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the SWIFT GRB 250129A errorbox  55139 sec after notice time (55220 sec after trigger time) at 2025-01-29 20:05:29 UT, with upper limit up to  18.9 mag.
The observations began at zenith distance = 83 deg. The sun  altitude  was -59.8 deg.
Observations were continued observations at 30, 31 Jan, 01, 02 Feb.


MASTER-SAAO robotic telescope  located in South Africa (South African Astronomical Observatory) was pointed to the SWIFT GRB 250129A errorbox 62515 sec after notice time (62595 sec after trigger time) at 2025-01-29 22:08:24 UT, with upper limit up to  20.2 mag. The observations began at zenith distance = 81 deg. The sun  altitude  is -39.2 deg.

MASTER OT J131442.41+050150.4 presents from 29 jan (240s after trigger time) up to now (~21.5m, unfiltered) all 4 days with light curve with complicated structure .


The galactic latitude b = 67 deg., longitude l = 319 deg.


Real time updated cover map and discovered OT  are available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2760136

GCN Circular 39116

Subject
Konus-Wind detection of GRB 250129A
Date
2025-02-01T17:29:52Z (8 months ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
Via
email
D. Frederiks, A.Lysenko, A. Ridnaya, D. Svinkin, A. Tsvetkova,
M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:

The long GRB 250129A (Swift detection: Beardmore et al., GCN 39066)
was detected by Konus-Wind (KW) in the waiting mode.

A Bayesian block analysis of the KW waiting mode data in the 20-400 keV band
reveals a >6 sigma count rate increase in the interval
from T0-66 s to T0+208 s where T0 = T0(BAT) = 04:45:09 UT.

The KW light curve of this burst is available
at http://www.ioffe.ru/LEA/GRBs/GRB250129A/

Modeling the time-integrated spectrum of the burst
by a power law with exponential cutoff (CPL) model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -1.74 (-0.07, + 0.07) and Ep = 66(-8,+8) keV.
In the 10 keV -10 MeV band, standard for the KW analysis,
the burst fluence is (6.71 ± 0.14)x10^-6 erg/cm^2
and the 2.944 s peak energy flux is (1.46 ± 0.18)x10^-7 erg/cm^2/s.

Assuming the redshift z=2.151 (Schneider et al., GCN 39071)
and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the burst isotropic energy release E_iso to (7.7 ± 0.2)x10^52 erg,
the isotropic peak luminosity L_iso to (5.3 ± 0.7)x10^51 erg/s, and
the rest-frame peak spectral energy Ep,z to (207 ± 22) keV.
With the obtained estimates, GRB 250129A is consistent with 68% prediction
bands of 'Amati' and 'Yonetoku' relations for the sample
of >300 long KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021),
see http://www.ioffe.ru/LEA/GRBs/GRB250129A/GRB250129A_rest_frame.pdf

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

GCN Circular 39115

Subject
GRB 250129A: 1.3m DFOT Optical observations
Date
2025-02-01T17:07:56Z (8 months ago)
From
Amit Kumar Ror at ARIES <mitturor77894@gmail.com>
Via
email
Amit K. Ror, Anshika Gupta, Kiran, Shashi B. Pandey, Kuntal Mishra (ARIES)
report:


We observed the field of GRB 250129A detected by the Swift Burst Alert
Telescope (Swift team, Beardmore et al. 2025; GCN 39066) with the 1.3m
Devasthal Fast Optical Telescope (DFOT), located at the Devasthal
Observatory of the Aryabhatta Research Institute of Observational Sciences
(ARIES), India. The observations were started on 2025-01-30 at 22:57:11 UT,
i.e., ~ 1.76 days after the Swift-BAT trigger. We have taken multiple
frames with an exposure time of 300 s in the R filter. We stacked the
images after the alignment. We detected an optical afterglow in our stacked
image within the error box of the enhanced Swift-XRT position by Goad et
al. 2025 (GCN 39082). Further observations of the burst are still ongoing.
We obtain the following preliminary magnitude in the stacked image:


Date Start_UT T_start-T0 (days) Filter  Exp time (s)  Magnitude

=========================================================

2025-01-30 22:57:11     ~1.76     R     300s*12     19.52 +/- 0.03


Our detection is consistent with Francile et al. 2025 (GCN 39065); Lipunov
et al. 2025 (GCN 39070); Schneider et al. (GCN 39071); Belkin et al. 2025
(GCN 39072); Izzo et al. 2025 (GCN 39073); Izzo et al. 2025 (GCN 39074);
Francile et al. 2025 (GCN 39075); Ghosh et al. 2025 (GCN 39077); Schneider
et al. 2025 (GCN 39078); Brivio et al. 2025 (GCN 39079); Siegel et al. 2025
(GCN 39085); Zheng et al. 2025 (GCN 39090); Schlekat et al. 2025 (GCN
39091); Antier et al. 2025(GCN 39096); Odeh et al. 2025 (GCN 39097); Ferro
et al. 2025(GCN 39098); Bochenek et al. 2025 (GCN 39099);Malesani et al.
2025 (GCN 39100); Romanov et al. 2025 (GCN 39101); Zheng et al. 2025 (GCN
39102); Zheng et al. 2025 (GCN 39102); Watson et al. 2025 (GCN 39104);
Vinko et al. 2025(GCN 39105); Akl et al. 2025 (GCN 39106); Moskvitin et al.
2025 (GCN 39107); Giovanni et al. 2025 (GCN 39109); Schlekat et al. 2025
(GCN 39110) and Schlekat et al. 2025 (GCN 39114).


The magnitude is not corrected for the Galactic extinction in the direction
of the burst. Photometric calibration is performed using the standard stars
from the USNO-B1.0 catalogue. This circular may be cited.

GCN Circular 39114

Subject
GRB 250129A: Liverpool Telescope observations suggest continued engine activity
Date
2025-02-01T13:22:21Z (8 months ago)
From
Ben Gompertz at U of Birmingham <b.gompertz@bham.ac.uk>
Via
email
B. P. Gompertz (U. Birmingham), D. B. Malesani (DAWN/NBI and Radboud), R. Brivio (INAF-OAB) and A. J. Levan (Radboud) report on behalf of a larger collaboration:

We initiated follow-up observations of GRB 250129A (Beardmore et al., GCN 39066) with the IO:O camera on the 2m robotic Liverpool Telescope (LT). Observations were taken across the nights of 2025-01-30 and 2025-01-31, consisting of 5x180 s exposures in each of the SDSS r and i filters. In a preliminary analysis, we measure the following AB magnitudes:

t-t0(d)  exp(s)  filt        mag     error
2.06     900      r           20.29   0.04
2.93     900      r           20.40   0.05

Magnitudes are calibrated against nearby Pan-STARRS stars and are not corrected for galactic extinction.

Our measurements indicate either minimal evolution between 2 and 3 days after trigger, or a continuation of the flaring behaviour observed during the first 24 hours, as noted by Belkin et al. (GCN 39072), Francile et al. (GCN 39075), Brivio et al. (GCN 39079), Zheng & Filippenko (GCN 39090), Antier et al. (GCN 39096), and Malesani et al. (GCN 39100).

GCN Circular 39110

Subject
GRB 250129A: Skynet Continued Optical Observations
Date
2025-02-01T03:46:26Z (8 months ago)
From
dschlekat@unc.edu
Via
Web form
Donovan Schlekat, Dylan Dutton, Daniel Reichart, Joshua Haislip, Vladimir Kouprianov, Daryl Janzen, Arie Verveer, and John Kennewell report on behalf of the Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill.

We continued to observe the optical counterpart of GRB 250129A (Beardmore et al., GCN 39066) with two of Skynet’s 0.4m PROMPT telescopes at the Cerro Tololo Inter-American Observatory, Skynet’s 0.4m PROMPT telescope located in Meckering, Australia, and a 0.5m telescope at the Astronomical Observatory of the Jagiellonian University in Krakow, Poland. The observations began ~14 hours after the trigger and ended ~60 hours after the trigger. We detected the optical transient in both the V and R bands.

The observed position of the optical counterpart was consistent with the coordinates described in other reports (Francile et al., GCN 39065; Beardmore et al., GCN 39066; Schneider et al., GCN 39071; Belkin et al., GCN 39072; Izzo et al., GCN 39073; Izzo & Malesani, GCN 39074; Ghosh et al., GCN 39077; Schneider et al., GCN 39078; Brivio et al., GCN 39079; Siegel et al., GCN 39085; Zheng & Filippenko, GCN 39090; Schlekat et al., 39091; Antier et al., 39096; Odeh et al., GCN 39097; Ferro et al., GCN 39098; Bochenek et al., GCN 39099; Malesani et al., GCN 39100; Romanov, GCN 39101; Zheng & Filippenko, GCN 39102; Watson et al., GCN 39104; Vinko et al., GCN 39105; Akl et al., GCN 39106; Moskvitin et al., GCN 39107; Calapai, GCN 39109).

We observed the optical counterpart fading with a temporal index of ~1.75, consistent with the value reported by Akl et al. (GCN 39106).

Select photometry is reported below.

Tmid - T0 (days)| Telescope | Filter | Exposure (s) | Mag.    | Mag Error
---------------------------------------------------------------------------
0.591           | PROMPT-MO | R      | 100x80       | 17.482  | 0.051
1.191	        | PROMPT-5  | R      | 300          | 18.725  | 0.054
2.114           | PROMPT-5  | R      | 10x300       | 19.828  | 0.057
2.566           | PROMPT-MO | R      | 150x80       | 20.153  | 0.058

Our images have been calibrated using stars from the APASS catalog. Magnitudes were not corrected for dust extinction. Additional Skynet observations are ongoing.

GCN Circular 39109

Subject
GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
Date
2025-02-01T00:21:27Z (8 months ago)
From
Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, Messina, Italy <giovannicalapai@tiscali.it>
Via
Web form
Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, (Messina) Italy 
Member of: GRB/UAI Gamma Ray Burst Section of Unione Astrofili Italiani. 

Report:

We observed the field of GRB 250129A (Swift trigger=1285812, Page et al., GCN 39066) with the 11 inches Schmidt-Cassegrain (Celestron 11) telescope F/D=6,3. 
  
The observations were started at 2025-01-31 01:00 UT (approximately 44.25 hours after burst) stacking a set of unfiltered CCD image. The observations were carried out with clear skies and fair visibility conditions.

The OT was detected at the following position:

RA    (J2000.0)  13h 14m 42.38s   
Decl. (J2000.0) +05° 01' 50.8" 

Photometry was obtained using nearby PanSTARRS stars as follows: 

Observation    Mid-Time    T-T0 (hr)      Exposure        Filter      Mag.      Err.
2025-01-31   02:34:24 UT    45.82         105x60s          CR        20.14    +/-0.30

Magnitude was calibrated with the nearby PanSTARRS stars converted using Lupton (2005) equations. 
No correction for galactic dust extinction was applied.

Our observations are consistent with other already reported Lipunov et al. (GCN 39070), Gompertz et al. (GCN 39072), Malesani et al. (GCN 39073), Izzo et al. (GCN 39074), Lipunov et al. (GCN 39075), Ghosh et al. (GCN 39077), Schneider et al. (GCN 39078), Brivio et al. (GCN 39079), Siegel et al. (GCN 39085), Zheng et al. (GCN 39090), Schlekat et al. (GCN 39091), Antier et al. (GCN 39096), Odeh et al. (GCN 39097), Ferro et al. (GCN 39098), Bochenek et al. (GCN 39099), Malesani et al. (GCN 39100), Romanov (GCN 39101), Zheng et al. (GCN 39102), Watson et al. (GCN 39104), Vinko et al. (GCN 39105), Akl et al. (GCN 39106), Moskvitin et al. (GCN 39107).

The message may be cited.

GCN Circular 39107

Subject
GRB 250129A: SAO RAS optical observations
Date
2025-01-31T12:29:18Z (8 months ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
Web form
A. Moskvitin, O. Spiridonova, Yu. Sotnikova (SAO RAS), 
A. Ghosh, S. Razzaque (CAPP, University of Johannesburg)

We observed the field of GRB 250129A (Beardmore et al., GCN 39066)
with the SAO RAS 1-m telescope Zeiss-1000 on January 30, 23:46:43 --
January 31, 00:19:22 UT (t_mid - T0 = 43.298 hours = 1.8041 days). 
We obtained 5 x 300 sec. images in Rc band.

The OT (Francile et al., GCN 39065; GCN 39075, Beardmore et al., 
GCN 39066, Schneider et al., GCN 39071, Belkin et al., GCN 39072; 
Izzo et al., GCN 39073; Izzo and Malesani, GCN 39074; Ghosh et al., 
GCN 39077; Schneider et al., GCN 39078; Brivio et al., GCN 39079;
Siegel and Beardmore, GCN 39085; Zheng and Filippenko, GCN 39090; 
GCN 39102; Schlekat et al., GCN 39091; Antier et al., GCN 39096; 
Odeh et al., GCN 39097; Ferro et al., GCN 39098; Bochenek and Perley, 
GCN 39099; Malesani et al., GCN 39100; Romanov, GCN 39101; 
Watson et al., GCN 39104; Vinko et al., GCN 39105; Akl et al., 
GCN 39106) is clearly detected in the stacked frame 
with the brightness of R = 19.65 +/- 0.13 (calibrated against R2 
magnitudes of nearby UNSO-B1 stars and not corrected for the MW
extinction).

GCN Circular 39106

Subject
GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
Date
2025-01-31T11:10:13Z (8 months ago)
From
Dalya Akl at American Uni. SHJ <dalyaakl.d@gmail.com>
Via
Web form
Dalya Akl (AUS), Alan M. Watson (UNAM), Camila Angulo (UNAM), Sarah Antier (OCA/IJCLAB), Benjamin Schneider (LAM), Rosa L. Becerra (Università degli Studi di Roma Tor Vergata), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Jean-Grégoire Ducoin (CPPM), Francesco Magnani (CPPM), and Margarita Pereyra (UNAM) report:

We continued imaging the field of the Swift GRB 250129A (Beardmore et al., GCN Circ. 39066) during the commissioning of the COLIBRÍ (SVOM/F-GFT) telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. 

We observed with the OGSE engineering test camera in a red filter approximating SDSS r starting at 2025-01-31 07:30:00 UTC. Compared to our observations from the previous night, we see a decay with an index of about -1.8 between T+30 and T+52 hours, less steep than the very sharp decline reported by (Zheng & Filippenko, GCN Circ. 39102) from T+28.5 to T+33.5 hours.

Further observations are planned.

We warmly thank the COLIBRÍ 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.

GCN Circular 39105

Subject
GRB 250129A: optical photometry from Konkoly
Date
2025-01-31T10:23:30Z (8 months ago)
From
Jozsef Vinko at Konkoly Observator <vinko@konkoly.hu>
Via
email
GRB 250129A: optical photometry from Konkoly 

J. Vinko, A. Horti-David, R. Konyves-Toth, Zs. Bora, L. Kriskovics, A. Pal, R. Szakats 
(Konkoly Observatory, Hungary) 

We report detection and photometry of the optical afterglow of GRB 250129A 
(Beardmore et al., GCN 39066) taken with the RC80 robotic telescope at Piszkesteto Station of Konkoly 
Observatory, Hungary. The observations started on 2025-01-29 23:35:21 UT, 
18.84 hours after the trigger. 5 sets of 300 sec frames were collected through 
Sloan g', r'- and i' bands. The optical afterglow (Francile et al., GCN 39065; 
Beardmore et al., GCN 39066; Schneider et al., GCN 39071; Belkin et al., GCN 39072; 
Izzo et al., GCN 39073; Izzo & Malesani, GCN 39074; Gosh et al., GCN 39077; 
Schneider et al., GCN 39078; Brivio et al., GCN 39079; Siegel et al., GCN 39085; 
Zheng et al. GCN 39090; Schlekat et al., GCN 39091; Antier et al., 39096; 
Odeh et al., GCN 39097; Ferro et al., GCN 39098; Bochenek et al., GCN 39099; 
Malesani et al., GCN 39100; Romanov, GCN 39101; Zheng & Filippenko, GCN 39102; 
Watson et al. GCN 39104) was detected on the stacked frames with the following magnitudes, 
calibrated via nearby PS1 stars: 

Date UT-middle t-T0(days) Exp(s) g'(AB) r'(AB) i'(AB) 
2025-01-30 00:13:39 0.7849 5x300 20.32 (0.21) 19.29 (0.08) 19.12 (0.10) 

The magnitudes above are not corrected for galactic extinction.

GCN Circular 39104

Subject
GRB 250129A: COLIBRÍ Optical Observations
Date
2025-01-31T07:13:32Z (8 months ago)
From
Alan Watson at UNAM <alan@astro.unam.mx>
Via
email
Alan M. Watson (UNAM), Camila Angulo (UNAM), D. Akl (AUS), S. Antier
(OCA), Benjamin Schneider (LAM), Stéphane Basa (UAR Pytheas), William
H. Lee (UNAM), Jean-Luc Atteia (IRAP), Rosa Becerra (Università degli
Studi di Roma Tor Vergata), Nathaniel R. Butler (ASU), Damien Dornic
(CPPM), Francis Fortin (IRAP), J.-G. Ducoin (CPPM), Francesco Magnani
(CPPM) and Margarita Pereyra (UNAM) report:

We imaged the field of the Swift GRB 250129A (Beardmore et al., GCN
Circ. 39066) during the commissioning of the COLIBRÍ (SVOM/F-GFT)
telescope at the Observatorio Astronómico Nacional on the Sierra de
San Pedro Mártir in Mexico.

We observed with the OGSE engineering test camera in a red filter that
approximates SDSS r from 2025-01-30 07:01 to 12:54 UTC. In the subset
of our data from 2025-01-30 12:01 to 12:54, from 31.27 to 32.15 hours
after the event, with a total exposure of 2220 seconds, we clearly
detect the afterglow with

r = 19.38 +/- 0.04

This magnitude is not corrected for Galactic extinction. The data were
reduced using custom software and then analysed and calibrated against
the PS1 catalog using the STDWeb service.

Further observations are planned.

We warmly thank the COLIBRÍ 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.

GCN Circular 39102

Subject
GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
Date
2025-01-30T22:40:51Z (8 months ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
email
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on

behalf of the KAIT GRB team:


The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located

at Lick Observatory, continued observing the afterglow of the

GRB 250129A (Francile et al., GCN 39065; Beardmore et al.,

GCN 39066; Schneider et al., GCN 39071; Belkin et al., GCN 39072;

Izzo et al., GCN 39073; Izzo & Malesani, GCN 39074; Gosh et al.,

GCN 39077; Schneider et al., GCN 39078; Brivio et al., GCN 39079;

Siegel et al., GCN 39085; Zheng et al. GCN 39090; Schlekat et al.,

GCN 39091; Antier et al., 39096; Odeh et al., GCN 39097; Ferro

et al., GCN 39098; Bochenek et al., GCN 39099; Malesani et al.,

GCN 39100; Romanov, GCN 39101) in the clear (roughly R) band.

Observation started at ~28.5h after the burst and lasted for ~5.0h.

The OT was still clearly detected in every individual image. Our

photometry results show that the OT was in a single power-law decay

phase, decayed from ~18.6 mag (~28.5h) to ~19.5 mag (~33.5h) with

a decay index of ~4.1, much steeper compared to the value of ~0.85

reported by Bochenek et al. (GCN 39099). This indicating the OT is

likely in a post jet-break phase.

GCN Circular 39101

Subject
GRB 250129A: iTelescope optical observation
Date
2025-01-30T20:15:55Z (8 months ago)
From
Filipp Dmitrievich Romanov at Amateur astronomer <filipp.romanov.27.04.1997@gmail.com>
Via
email
I observed the field of GRB 250129A (Beardmore et al., GCN Circ.
39066) remotely using telescope T11 (0.51-m f/6.8 reflector + CCD +
f/4.5 focal reducer) of iTelescope.Net (located in Utah Desert Remote
Observatory at Great Basin Desert, Beryl Junction, Utah, USA) on
2025-01-30. Five images (exposure times of 300 seconds, BINx1) were
obtained with Rc filter. I detected the optical afterglow in all
images in the UVOT position. I measured the magnitude of it = 19.7 +/-
0.2 in the stacked image (mid time 13:11:06 UT = 32.43 h. after the
trigger) compared to r magnitudes of nearby stars from Pan-STARRS DR1
catalogue (Chambers et al., 2016).

Magnitude was not corrected for Galactic extinction.

Stacked image: https://www.flickr.com/photos/filipp-romanov/54297183051/

F. D. Romanov (AAVSO).

GCN Circular 39100

Subject
GRB 250129A: NOT optical observations of continuining activity
Date
2025-01-30T17:47:55Z (8 months ago)
From
Daniele B. Malesani at IMAPP / Radboud University <d.malesani@astro.ru.nl>
Via
Web form
D. B. Malesani (DAWN/NBI), K. E. Heintz (DAWN/NBI), B. P. Gompertz (Birmingham), A. Martin-Carrillo (UCD), A. M. Bochenek (LJMU), R. Brivio (INAF/OABr), A. M. Kadela (NOT, NBI), B. N. Hauptmann (NOT and DTU Space), report on behalf of a larger collaboration:

We observed the nice optical afterglow of GRB 250129A (Beardmore et al., GCN 39066) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Seeing conditions were sub-optimal, around 2". Observations were carried out in the r and i filters (exposure time of 3x200 s each).

At a mean epoch of Jan 30.0916 UT (21.44 hr after the trigger), we measure for the afterglow r = 19.24 +- 0.03 (AB), calibrated against nearby objects from the Pan-STARRS catalog.

We note that this value is ~0.35 mag fainter than the measurement reported at a later epoch by Bochenek & Perley (24.1 hr after trigger; GCN 39099). Accurate relative comparison using a shared set of calibration stars confirms the rebrightening. Flaring was thus still ongoing even ~24 hr after the trigger, continuing the earlier trend highlighted by Belkin et al. (GCN 39072), Francile et al. (GCN 39075), Brivio et al. (GCN 39079), Zheng & Filippenko (GCN 39090), and Antier et al. (GCN 39096).

We encourage further follow-up of this unusual event at all wavelengths.

GCN Circular 39099

Subject
GRB 250129a: Liverpool Telescope optical follow-up
Date
2025-01-30T14:06:13Z (8 months ago)
From
A. Bochenek at Liverpool John Moores University <a.m.bochenek@2023.ljmu.ac.uk>
Via
Web form
A. Bochenek and D. A. Perley (LJMU) report:

We observed the field of GRB250129a (Beardmore et al., GCN 39066) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 6x90s exposures in the SDSS r’ filter starting at 2025-01-30 04:53:17 UT, approximately 24.1 hours after the trigger. Three of the images had to be discarded due to autoguider issues.
 
We report a detection in the stacked images of r = 18.91 ± 0.03 mag. Our detection is consistent with the re-brightening (Brivio et al., GCN 39079, Zheng et al., GCN 39090) and subsequent observations of the afterglow (Odeh et al., GCN39097, Ferro et al. GCN39098). This implies slow decay, approx. 2 magnitudes in r-band from (clear) R ~17.1 at 6.9h post trigger (Zheng et al., GCN 39090) to this work’s r = 18.91 at 24.1h, with the decay index of approximately ~0.85.
 
The photometry was obtained using nearby PanSTARRS standards and was not corrected for extinction.

GCN Circular 39098

Subject
GRB 250129A: TNG NIR afterglow detection
Date
2025-01-30T13:08:07Z (8 months ago)
From
Matteo Ferro at INAF-OAB <matteo.ferro@inaf.it>
Via
Web form
M. Ferro, R. Brivio, P. D'Avanzo, S. Covino (INAF-OAB), A. Rossi (INAF-OAS), D. B. Malesani (DAWN/NBI & Radboud Univ.), A. Melandri (INAF-OAR), G. Mainella e M. Cecconi (INAF-TNG)  on behalf of the CIBO collaboration report:

We observed the field of the GRB250129A detected by the Swift (Beardmore et al., GCNC 36556) with the Italian 3.6m TNG telescope equipped with the near-infrared camera NICS to follow up its afterglow. A series of images were obtained with the J and H filters starting on 2025-01-30T06:16:34 UT (i.e. 25.5 hours post T0). The afterglow (Lipunov et al., GCN 39070; Schneider et al., GCN 39071; Gompertz et al., GCN 39072; Izzo et al., GCN 39073; Izzo et al., GCN 39074; Francile et al., GCN 39075; Ghosh et al., GCN 39077; Schneider et al., GCN 39078; Brivio et al., GCN 39079; Heintz et al., GCN 39081; Siegel et al., GCN 39085; Zheng et al., GCN 39090; Schlekat et al., GCN 39091; Antier et al., GCN 39096; Odeh et al., GCN 39097) is detected in the co-added image with a preliminary result of H(Vega)~16.7 mag (calibrated against the 2MASS catalogue).

GCN Circular 39097

Subject
GRB 250129A: AKO Optical Afterglow Detection
Date
2025-01-30T11:41:15Z (8 months ago)
From
Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>
Via
email
Mohammad Odeh (Al-Khatim Observatory, AKO, operated by the International
Astronomical Center in Abu Dhabi, UAE), and Shaikha Alshamsi, Nuha Manal
Pattani, and Nidhal Guessoum (American University of Sharjah, UAE), report:

 

We observed the field of GRB 250129A (Beardmore et al., GCN 39066) using our
0.36m f/7.7 robotic telescope. The observation session began on 29 January
2025 at 21:07 UT and continued until 22:02 UT, with a midpoint at 21:36 UT,
approximately 16.8 hours after the trigger.

 

We obtained multiple 180-second exposures using the Ic filter. The optical
afterglow was clearly detected at:

R.A. (J2000): 13:14:42.40

Dec. (J2000): +05:01:50.4

 

Our detection is consistent with the results of Francile et al., GCN 39065;
Beardmore et al., GCN 39066; Schneider et al., GCN 39071; Belkin et al., GCN
39072; Izzo et al., GCN 39073; Izzo & Malesani, GCN 39074; Ghosh et al., GCN
39077; Schneider et al., GCN 39078; Brivio et al., GCN 39079; Siegel et al.,
GCN 39085; Zheng et al., GCN 39090; Schlekat et al., GCN 39091; Antier  et
al., GCN 39096.

 

The following observation was calculated using the Atlas catalogue as a
reference:

----------------------------------------------------------------------------
-

ObsTime (mid), Exposure (sec), Filter, Mag

----------------------------------------------------------------------------
-

2025-01-29T21:35:48Z, 18 x 180s (stacked), Ic, 18.7 +/- 0.22

----------------------------------------------------------------------------
-

The magnitude is not corrected for galactic extinction.

GCN Circular 39096

Subject
GRB 250129A: GRANDMA/TAROT optical afterglow detection
Date
2025-01-30T10:05:34Z (8 months ago)
From
Patrice Hello at IJCLAB, Orsay <patrice.hello@ijclab.in2p3.fr>
Via
Web form
S. Antier (OCA/IJCLAB), P. Hello (IJCLAB), P. Gokuldass (ERAU), A. Klotz (IRAP), C. Limonta, M. Boer, Q. Andre, A. Durroux (OCA), N. Guessoum (AUS), Haowei Peng (Tsinghua), C. Andrade,  M. Coughlin (UMN), P-A Duverne (APC), S. Karpov (FZU), T. Pradier (Unistra/IPHC), D. Turpin (CEA-Saclay/Irfu) on behalf of the GRANDMA collaboration:

we observed the field of GRB 250129A, detected by Swift (Beardmore et al., GCN 39066) using TAROT/TCH and TAROT/TCA. Observations began 1 min after T0 without filter, and we took a series of images with various exposure times from 1.76 min to 73 min post T0.

We detected the optical afterglow candidate in he first (earliest) measurement with TAROT/TCH (5x30s exposure time) at T0+2.96min with mag=17.48 +/- 0.08 (in R band). The data were reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022), using Skymapper for reference. Processing of remaining data is ongoing.

Our measurements are compatible with early measurements, GCNs 39070, 39072, 39073, 39074, 39078, 39079.

GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).

GCN Circular 39091

Subject
GRB 250129A: Skynet optical observations
Date
2025-01-29T23:18:26Z (8 months ago)
From
dschlekat@unc.edu
Via
Web form
Donovan Schlekat, Dylan Dutton, Daniel Reichart, Joshua Haislip, and Vladimir Kouprianov report on behalf of the Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill.

We observed the field of GRB 250129A with two of Skynet's PROMPT telescopes located at the Cerro Tololo Inter-American Observatory. The observation began at 05:12:20 UT on January 29 2025, roughly 27 minutes after the Swift-BAT trigger (Beardmore et al., GCN 39066). Observations were performed in the B, V, R, and I bands. Exposure lengths were calculated using our automated exposure length scaling model.

We detect the optical afterglow consistent with the coordinates reported by other facilities (Francile et al., GCN 39065; Beardmore et al., GCN 39066; Schneider et al., GCN 39071; Belkin et al., GCN 39072; Izzo et al., GCN 39073; Izzo & Malesani, GCN 39074; Ghosh et al., GCN 39077; Schneider et al., GCN 39078; Brivio et al., GCN 39079; Siegel et al., GCN 39085; Zheng et al., GCN 39090).

The coordinates are:
R.A. (J2000): 13:14:42.39
Dec. (J2000): 05:01:50.22

We detect the object in the B, V, R, and I band. The initial detection photometry for each band is reported below. Additional Skynet observations are ongoing.

Tmid - T0 (s)| Telescope | Filter | Exposure (s) | Mag	   | Mag Error
------------------------------------------------------------------
1674.49      | PROMPT-5  | B      | 59           | 17.525  | 0.051
1678.99	     | PROMPT-6  | V      | 34           | 16.902  | 0.054
1711.99      | PROMPT-6  | R      | 22           | 16.628  | 0.057
1938.49      | PROMPT-6  | I      | 19           | 16.111  | 0.095

Our images have been calibrated using stars from the APASS catalog. Magnitudes were not corrected for dust extinction.

GCN Circular 39090

Subject
GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
Date
2025-01-29T22:21:18Z (8 months ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
email
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on

behalf of the KAIT GRB team:


The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located

at Lick Observatory, responded to GRB 250129A detected by Swift

(Beardmore et al., GCN 39066) starting at 09:25 UT, ~4.68h after

the bust. Observations were performed in the clear (roughly R)

filter with a set of 60s exposures and lasted for ~2.2h. The

optical afterglow (Francile et al., GCN 39065; Beardmore et al.,

GCN 39066; Schneider et al., GCN 39071; Belkin et al., GCN 39072;

Izzo et al., GCN 39073; Izzo & Malesani, GCN 39074; Gosh et al.,

GCN 39077; Schneider et al., GCN 39078; Brivio et al., GCN 39079;

Siegel et al., GCN 39085) was clearly detected in every individual

image. Our photometry results show that the OT rebrightened since

~4.68h (~16.7 mag) and reached a double peak at ~4.99h (~16.3 mag)

and again at 5.2h (~16.3 mag), then decayed afterword, with small

flares during decay phase, till ~17.1 mag at ~6.90h.

GCN Circular 39089

Subject
GRB 250129A: Swift-XRT refined Analysis
Date
2025-01-29T22:15:26Z (8 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M. Ferro
(INAF-OAB), R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), M. A. Williams
(PSU), S. Dichiara (PSU), J.A. Kennea (PSU), A.P. Beardmore (U.
Leicester) and P.A. Evans report on behalf of the Swift-XRT team:

We have analysed 10 ks of XRT data for GRB 250129A, from 147 s to 46.4
ks after the  BAT trigger. The data comprise 10 s in Windowed Timing
(WT) mode (taken while Swift was slewing), with the remainder in Photon
Counting (PC) mode. 

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=3.64 (+1.35, -0.10). At T+1185 s  the
decay flattens to an alpha of 0.15 (+/-0.07) before breaking again at
T+23.0 ks to a final decay with index alpha=2.2 (+0.7, -0.6).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.92 (+0.16, -0.10). The
best-fitting absorption column is  consistent with the Galactic value
of 2.4 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 3.4 x 10^-11 (3.6 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 2.4 x 10^20 cm^-2
Intrinsic column:    2 (+/-38) x 10^20 cm^-2 at z=2.151
Photon index:	     1.92 (+0.16, -0.10)

If the light curve continues to decay with a power-law decay index of
2.2, the count rate at T+24 hours will be 0.011 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.8 x
10^-13 (4.0 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/01285812.

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

GCN Circular 39085

Subject
GRB 250129A: Swift/UVOT Detection
Date
2025-01-29T14:51:44Z (8 months ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
Via
Web form
M. H. Siegel (PSU) and A. P. Beardmore (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 250129A
1185 s after the BAT trigger (Beardmore et al., GCN Circ. 39066).
A source consistent with the XRT position (Goad et al., GCN Circ. 39082) and
the previously reported optical counterpart (Francile et al., GCN Circ. 39065;
Belkin et al, GCN Circ. 39072; Ghosh et al., GCN Circ 39077; Schneider et al.
GCN Circ. 39078, Brivio et al., GCN Circ. 39079.) is detected in the initial UVOT
exposures. The UVOT light curve shows some evidence of fading.

The lack of detection of this bright burst in the NUV filters would be consistent
with the redshift of 2.15 reported by Schneider et al. (GCN Circ, 39071) and
Izzo et al. (GCN Circ. 39073).

The preliminary UVOT position is:
    RA  (J2000) =  13:14:42.41 = 198.67670 (deg.)
    Dec (J2000) = +05:01:50.3  =   5.03064 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).

Preliminary detections 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 (fc)        1185         1335          147      17.43+/-0.04
white             1468         1835           58      17.39+/-0.07
white             5450         5650          196      17.63+/-0.04
v                 1343         1885           77      17.24+/-0.17
v                10957        11667          690      17.98+/-0.08
b                 1444         1809           58      17.29+/-0.11
b                 5245        16960          649      17.63+/-0.04
u                 1418         1785           38      16.93+/-0.15
uvw2              5656         5845          186            >19.77

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.037 in the direction of the burst
(Schlegel et al. 1998).

GCN Circular 39082

Subject
GRB 250129A: Enhanced Swift-XRT position
Date
2025-01-29T12:57:34Z (8 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 809 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 250129A, 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 = 198.67662, +5.03073 which is equivalent
to:

RA (J2000): 13h 14m 42.39s
Dec (J2000): +05d 01' 50.6"

with an uncertainty of 2.4 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 39079

Subject
GRB 250129A: REM optical/NIR afterglow detection
Date
2025-01-29T11:27:01Z (8 months ago)
From
Riccardo Brivio at INAF-OAB <riccardo.brivio@inaf.it>
Via
Web form
R. Brivio, M. Ferro, P. D’Avanzo (INAF-OAB), D.B. Malesani (DAWN/NBI and Radboud Univ.), M. De Pasquale (Univ. of Messina), L. Izzo (INAF-OACn and DARK/NBI), A. Melandri (INAF-OAR), G. Tagliaferri,  S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team:

We observed the field of GRB 250129A detected by Swift (Beardmore et al., GCN 39066) 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 2025 January 29 at 04:47:12 UT (i.e. 123 s after the Swift trigger), and lasting for about 4 hours.

From preliminary photometry we detect the counterpart in the optical and NIR images at the position of the optical afterglow (Francile et al., GCN 39065; Schneider et al., GCN 39071; Belkin et al., GCN 39072; Izzo et al., GCN 39073; Izzo & Malesani, GCN 39074; Gosh et al., GCN 39077; Schneider et al., GCN 39078) with the following early-time magnitudes:

r = 17.7 +/- 0.3 (AB; calibrated against the Pan-STARRS catalogue)
at a mid-time of t - t0 = 128 s after the trigger.

H = 15.3 +/- 0.3 (Vega; calibrated against the 2MASS catalogue) 
at a mid-time t - t0 = 175 s after the trigger.

Our light curve spans between t0 + 128 s and t0+15120 s. It peaks around t0+2300 s and shows a rebrightening around t0+14300 s.

GCN Circular 39078

Subject
GRB 250129A: OHP/T193 optical and spectroscopy observations
Date
2025-01-29T10:51:22Z (8 months ago)
From
Benjamin Schneider at MIT <bschn@mit.edu>
Via
Web form
B. Schneider (LAM), C. Adami (LAM/Pytheas/AMU), J. Balcaen (OHP/Pytheas), A. Saccardi (CEA/Irfu), E. Le Floc'h (CEA/Irfu), J. Schmitt (OHP/Pytheas), J. P. Palmerio (CEA/Irfu), S. Basa (LAM/OHP/Pytheas/AMU), D. Turpin (CEA/Irfu) report on behalf of a larger collaboration:

We observed the field of the GRB 250129A (Beardmore et al., GCN 39066) with the T193 cm telescope at the Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained one exposure of 60s in the i-band using the red MISTRAL setting at 2025-01-29T05:14:39 (30 min after the trigger).

In the reduced image, the optical afterglow (Francile et al., GCN 39065; Schneider et al., GCN 39071; Belkin et al., GCN 39072; Izzo et al., GCN 39073; Izzo et al., GCN 39074; Ghosh et al., GCN 39077) is clearly detected at:

i = 16.34 +/- 0.02 mag (AB)

The photometric calibration was performed using nearby stars from the PanSTARRS catalog and is not corrected for Galactic extinction.

In addition, we obtained 15 min exposures during the twilight with the MISTRAL spectroscopic red setting, covering from 6400 to 9950 AA. In a preliminary reduction of the spectrum, the continuum is detected but the low S/N makes the redshift estimate difficult. Given the redshift provided by Schneider et al. (GCN 39071) and Izzo et al. (GCN 39073), we likely detected FeII (@2600 AA) and a hint of the MgII doublet at a corresponding redshift of 2.15.

We acknowledge the excellent support from Observatoire de Haute-Provence, in particular the Sophie observer Alice Radcliffe.

GCN Circular 39077

Subject
GRB 250129A: Early afterglow detection by LCO.
Date
2025-01-29T09:12:17Z (8 months ago)
From
ankur ghosh at CAPP, University of Johannesburg <ghosh.ankur1994@gmail.com>
Via
Web form
Ankur Ghosh, Soebur Razzaque (CAPP, University of Johannesburg),  Alexander Moskvitin, Yulia Sotnikova (SAO RAS), Naveen Dukiya (ARIES), Rahul Gupta (NASA GSFC) on behalf of a larger collaboration. 

We observed the field of the GRB 250129A triggered by Swift (Beardmore et al., GCN 39066) in V, r filters of the 0.4-m SCICAM QHY600 at the Las Cumbres Observatory Global Telescope (LCOGT) node located at Teide Observatory, Tenerife. The 0.4 m SCICAM QHY600 is equipped with 9576 x 6388 pixel CCD (FOV: 1.9 x 1.2 degrees, scale: 0.74 arcsec/pixel) but we only used the FOV of 30 x 30 arcmin for our observation.
Observations began on January 29, 2025, starting 1.17 hours after the GRB trigger.

We clearly detect the optical transient (OT) reported by GCNs ( Francile, GCN 39065; Schneider et al., GCN 39071; Belkin et al., GCN 39072; Izzo et al., GCN 39073, Izzo et al., GCN 39074)  in our V, r band images. Follow-up observations are on going. 


|Date|		|UTstart|	|t-T0 (hours)|	|Exp (sec)|	|Filter|	|Magnitude| 
---------------------------------------------------------------------------------------------------      
2025-01-29	 05:55:21.79	1.17		1 x 600 	r		r = 17.05 +/- 0.01

2025-01-29	 06:22:59.80	1.63		1 x 600 	V		V = 17.34 +/- 0.01


The field was calibrated against nearby APASS stars, with magnitudes converted using Lupton (2005) equations, and has not been corrected for Galactic extinction.

GCN Circular 39075

Subject
Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
Date
2025-01-29T07:57:36Z (8 months ago)
Edited On
2025-02-14T14:32:09Z (8 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Vladimir Lipunov at Lomonosov Moscow State University <lipunov@sai.msu.ru>
Via
email


C.Francile,  F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix
Aguilar (OAFA),
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 (Lomonosov MSU),
O.Gress, N.Budnev(ISU),
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-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB 250129A ( A. P. Beardmore et al., GCN 39066, Francile et al., GCN 39065) error box.
The automatic light curve is a slowly evolving light curve with a flat maximum (~16.5m, clear filter like to the Sloan "g") at ~40 min after trigger. Reduction will be continued.

GCN Circular 39074

Subject
GRB 250129A: LCO optical observations
Date
2025-01-29T07:54:21Z (8 months ago)
From
luca.izzo@inaf.it
Via
Web form
L. Izzo (INAF-OACn and DARK/NBI), and D. B. Malesani (DAWN/NBI and Radboud Univ.) report:

We observed the field of GRB 250129A (Beardmore et al., GCN #39066) with the Sinistro instrument mounted on the 1-m telescope of the LCO network, located at the Cerro Tololo Observatory, Chile. Observations started on 2025 January 29 at 06:40 UT (1.89 hr after the GRB trigger). We obtained a single image of 240 s exposure in each of the SDSS-r and SDSS-i filters.

We detect a bright source consistent with the position of the optical afterglow reported by Swift-UVOT (Beardmore et al., GCN #39066) and by other ground-based facilities (Francile, GCN #39065; Schneider et al., GCN #39071; Belkin et al., GCN #39072; Izzo et al., GCN #39073). We measure preliminary magnitudes of r = 17.27 +/- 0.02 mag and i = 17.04 +/- 0.03 (AB), calibrated against nearby stars from the Pan-STARRS catalog.

This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 101004719. We also acknowledge the use of the ECSnoopy package by E. Cappellaro.

GCN Circular 39073

Subject
GRB 250129A: NOT optical observations and redshift confirmation
Date
2025-01-29T07:32:00Z (8 months ago)
From
Daniele B. Malesani at IMAPP / Radboud University <d.malesani@astro.ru.nl>
Via
Web form
Luca Izzo (INAF/OACn and DARK/NBI), Daniele B. Malesani (DAWN/NBI), Kasper E. Heintz (DAWN/NBI), Benjamin Gompertz (Birmingham), Antonio de Ugarte Postigo (CNRS, LAM and OCA), Benjamin N. Hauptmann (NOT, DTU Space ), Arthur M. Kadela (NOT, NBI), report on behalf of a larger collaboration:

We observed the optical counterpart (Francile, GCN 39065; Belkin et al., GCN 39072) of GRB 250129A (Beardmore et al., GCN 39066) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC imager. In a 300-s exposure with mid time 2025 Jan 29.222 UT (34.3 min after trigger), the counterpart is well detected with an AB magnitude r = 16.71 +- 0.02 (calibrated against nearby stars from Pan-STARRS). We measure the following coordinates (J2000):

RA = 13:14:42.40
Dec = +05:01:50.2

A sequence of three 1200-s spectra was secured using grism #4. Bright continuum is detected across the whole wavelength range. A number of absorption lines are detected, which, among others, we identify as H I, Si II, O I, C II, Si IV, C IV, Al II, Fe II, Mg II, all at a common redshift z = 2.15.

Our result is consistent with the value already measured by Schneider et al. (GCN 39071).

GCN Circular 39072

Subject
GRB 250129A: GOTO optical observations show brightening afterglow
Date
2025-01-29T07:30:35Z (8 months ago)
Edited On
2025-01-29T14:14:37Z (8 months ago)
From
Ben Gompertz at U of Birmingham <b.gompertz@bham.ac.uk>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Ben Gompertz at U of Birmingham <b.gompertz@bham.ac.uk>
Via
email
S. Belkin, B. P. Gompertz, D. O'Neill, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, A. Kumar, K. Ulaczyk, F. Jimenez-Ibarra, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, G. Ramsay, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, E. Palle and D. Pollacco report on behalf of the GOTO collaboration:

We report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022; Dyer et al. 2024) in response to the Swift detected GRB 250129A (Beardmore et al., GCN 39066). Targeted imaging obtained with GOTO-North covered the Swift localisation region starting at 2025-01-29 04:47:52 (+2.7m post trigger) with an average 5-sigma depth of 20.1 mag. The observations consisted of 4x90s exposures in the GOTO L-band (400-700 nm).

Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations of the same pointings.

We detect the optical afterglow reported by UVOT, also detected by Schneider et al. (GCN 39071), in two epochs centred at 5.2 minutes and 1.22 hours after trigger. The measured AB magnitudes are L = 17.86 ± 0.03 and L = 17.11 ± 0.02 respectively. The afterglow has therefore brightened by approximately 0.75 magnitudes over this period. Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.

GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).

GCN Circular 39071

Subject
GRB 250129A: VLT/X-shooter redshift of z = 2.151
Date
2025-01-29T07:24:10Z (8 months ago)
From
Benjamin Schneider at MIT <bschn@mit.edu>
Via
Web form
B. Schneider (LAM), A. Saccardi (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud Univ.), S. D. Vergani (CNRS, Obs. Paris/LUX), N. R. Tanvir (U. Leicester), V. D’Elia (ASI-SSDC and INAF-OAR), A. de Ugarte Postigo (CNRS, OCA and LAM), L. Izzo (INAF-OACn and DARK/NBI) report on behalf of the Stargate collaboration:

We observed the optical afterglow (Francile et al., GCN 39065) of GRB 250129A (Beardmore et al., GCN 39066) using the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph. Observations were performed via the rapid-response mode (RRM) system. Our spectra cover the wavelength range 3000-25000 AA, and consist of 4x600 s. The observation mid time was 2025 Jan 29.2528 UT (1.315 hr after the GRB).

In a 5 s image taken with the acquisition camera on Jan 29.237 UT, we detect the optical afterglow, for which we measure a magnitude r =16.72 +- 0.02 AB (calibrated against nearby stars from the Pan-STARRS catalogue).

In a preliminary reduction of the spectra, we clearly detect a continuum over the entire wavelength range. From the detection of a broad Lya absorption at ~3830 AA and multiple absorption features, which we interpret as due to N V, Si II, Si II*, O I, O I*, C II, C II*, Al II, Si IV, C IV, Fe II, Fe II*, Mg II, we infer a common redshift of z = 2.151.

We notice the presence of at least one intervening system at z = 1.89, as identified by an additional Lya absorption and multiple absorption lines (C II, Si II, Fe II, Al II, and Mg II).

We acknowledge expert support from the ESO staff in Paranal, in particular Abel de Burgos, Celia Desgrange, Luca Sbordone, Robert Klement, Rodrigo Palomino, and Sam Kim.

GCN Circular 39070

Subject
Swift GRB 250129A: Global MASTER-Net observations report
Date
2025-01-29T06:16:44Z (8 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
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-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB 250129A ( A. P. Beardmore et al., GCN 39066) errorbox  160 sec after notice time and 240 sec after trigger time at 2025-01-29 04:49:09 UT, with upper limit up to  20.7 mag. The observations began at zenith distance = 73 deg. The sun  altitude  is -41.0 deg. 

The galactic latitude b = 67 deg., longitude l = 319 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2760138

We obtain a following upper limits.  

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

     266 |         MASTER-OAFA |   C |    50 | 18.7 |        
     331 |         MASTER-OAFA |   C |   180 | 19.6 |  Coadd 
     496 |         MASTER-OAFA |   C |   510 | 20.0 |  Coadd 
     327 |         MASTER-OAFA |   C |    60 | 18.8 |        
     398 |         MASTER-OAFA |   C |    70 | 19.0 |        
     484 |         MASTER-OAFA |   C |    90 | 19.1 |        
     604 |         MASTER-OAFA |   C |   330 | 19.8 |  Coadd 
     590 |         MASTER-OAFA |   C |   110 | 19.3 |        
     716 |         MASTER-OAFA |   C |   130 | 19.3 |        
     867 |         MASTER-OAFA |   C |   160 | 19.4 |        
    1043 |         MASTER-OAFA |   C |   180 | 19.5 |        
    1230 |         MASTER-OAFA |   C |   180 | 19.6 |        
    1417 |         MASTER-OAFA |   C |   180 | 19.6 |        
    1603 |         MASTER-OAFA |   C |   180 | 19.7 |        
    1789 |         MASTER-OAFA |   C |   180 | 19.8 |        
    1975 |         MASTER-OAFA |   C |   180 | 19.8 |        
    2155 |         MASTER-OAFA |   C |   540 | 20.2 |  Coadd 
    2161 |         MASTER-OAFA |   C |   180 | 19.8 |        
    2347 |         MASTER-OAFA |   C |   180 | 19.8 |        
    2534 |         MASTER-OAFA |   C |   180 | 20.0 |        
    2714 |         MASTER-OAFA |   C |   540 | 20.3 |  Coadd 
    2720 |         MASTER-OAFA |   C |   180 | 20.0 |        
    2906 |         MASTER-OAFA |   C |   180 | 20.0 |        
    3092 |         MASTER-OAFA |   C |   180 | 20.0 |        
    3272 |         MASTER-OAFA |   C |   540 | 20.7 |  Coadd 
    3279 |         MASTER-OAFA |   C |   180 | 20.1 |        
    3465 |         MASTER-OAFA |   C |   180 | 20.1 |        
    3651 |         MASTER-OAFA |   C |   180 | 20.2 |        
    3831 |         MASTER-OAFA |   C |   540 | 20.7 |  Coadd 
    3838 |         MASTER-OAFA |   C |   180 | 20.1 |        
    4024 |         MASTER-OAFA |   C |   180 | 20.1 |        
    4210 |         MASTER-OAFA |   C |   180 | 20.2 |        
    4397 |         MASTER-OAFA |   C |   180 | 20.2 |        
    4583 |         MASTER-OAFA |   C |   180 | 19.9 |        
    4769 |         MASTER-OAFA |   C |   180 | 20.3 |        
    4955 |         MASTER-OAFA |   C |   180 | 19.7 |        
Filter C is a clear (unfiltred) band. 


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

GCN Circular 39066

Subject
GRB 250129A: Swift detection of a burst with an optical counterpart
Date
2025-01-29T05:12:01Z (8 months ago)
From
K.L. Page at U Leicester <klp5@leicester.ac.uk>
Via
email
A. P. Beardmore (U Leicester), S. Dichiara (PSU) and
K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 04:45:09 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 250129A (trigger=1285812).  Swift slewed immediately to the burst.
The BAT on-board calculated location is 
RA, Dec 198.689, +5.039 which is 
   RA(J2000) = 13h 14m 45s
   Dec(J2000) = +05d 02' 19"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is typical for an image trigger, the BAT light curve  
shows no significant peaks.

The XRT began observing the field at 04:47:47.6 UT, 158.6 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 198.67654,
5.03019 which is equivalent to:
   RA(J2000)  = 13h 14m 42.37s
   Dec(J2000) = +05d 01' 48.7"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 54 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 1.18e-08 erg cm^-2 s^-1 (0.2-10
keV).

UVOT took a finding chart exposure of nominal 150.000 seconds with the White
filter starting 1184 seconds after the BAT trigger. There is a candidate
afterglow in the list of sources generated on-board at
  RA(J2000)  =	13:14:42.42 = 198.67673
  DEC(J2000) = +05:01:50.3  =	5.03063
with a 90%-confidence error radius of about 1.10 arc sec. This position is 2.7
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.88. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.037.

Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk).
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 39065

Subject
Swift GRB 250129A: Global MASTER-Net OT detection
Date
2025-01-29T05:08:46Z (8 months ago)
Edited On
2025-02-14T14:31:55Z (8 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Vladimir Lipunov at Lomonosov Moscow State University <lipunov@sai.msu.ru>
Via
email
C.Francile,  F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA),
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 (Lomonosov MSU),
O.Gress, N.Budnev(ISU),
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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the  GRB250129.20 162 sec after notice time and 240 sec after trigger time at 2025-01-29 04:49:09 UT. On our second (60s exposure)  set , obtained 296 sec after tigger time at 2025-01-29 04:50:05 UT, we  found 1 optical transient within Swift error-box (ra=198.683 dec=5.03833 r=0.05) brighter than  18.3.


 T-Tmid      Date      Time       Expt.        Ra                Dec           Mag
---------|---------------------|-------|-----------------|-----------------|-------
     326   2025-01-29 04:50:05      60   (13h 14m 42.38s , +05d 01m 50.1s)     17.5

The 5-sigma upper limit has been about  18.3mag
The message may be cited.
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov