EP260119a
GCN Circular 43500
Subject
EP260119a: Assy AZT-20 optical observations
Date
2026-01-22T12:09:42Z (21 days ago)
From
Alina Volnova at IKI RAS <alinusss@gmail.com>
Via
Web form
A. Volnova (IKI), A. Pozanenko (IKI), M. Krugov (FAI), N. Pankov (IKI) report on behalf of IKI-GRB-FuN:
We observed the field of the EP260119a (Jiang et al., GCN 43447; GCN 43465; Cheng et al., GCN 43449) at the redshift of z ~ 5.47 (Corcoran et al., GCN 43469) with the AZT-20 telescope of Assy-Turgen observatory starting on 2026-01-20 (UT) 14:53 and taking several 60-second exposures in i' filter.
In the stacked frame we detect the optical counterpart (Fortin et al., GCN 43450; GCN 43455; Eyles-Ferris et al., GCN 43452; Moskvitin and Spiridonova, GCN 43463; Liu et al., GCN 43464; Ma et al., GCN 43466; Zheng et al., GCN 43468; Corcoran et al., GCN 43469; Bochenek and Perley, GCN 43472; Pankov et al., GCNs 43476, 43499; Jin et al., GCN 43496). Preliminary photometry and observational details are the following:
Date UT start t-T0 Exp. Filter Obj. Err. UL Site/Telescope
(mid,days) (n*s) (3sigma)
2026-01-20 14:53:00 1.63500 63*60 i' 22.7 0.2 23.2 Assy-Turgen/AZT-20
The photometry is based on several nearby SDSS stars (i-magnitudes) and is not corrected for the Galactic extinction.
GCN Circular 43499
Subject
EP260119a: Mondy and SAO RAS optical upper limits
Date
2026-01-22T10:50:53Z (21 days ago)
From
Alina Volnova at IKI RAS <alinusss@gmail.com>
Via
Web form
N. Pankov (IKI), A. Moskvitin (SAO RAS), A. Volnova (IKI), O. Spiridonova (SAO RAS), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of the IKI-GRB-FuN collaboration:
We observed the field of the EP260119a (Jiang et al., GCN 43447; GCN 43465; Cheng et al., GCN 43449) at the redshift of z ~ 5.47 (Corcoran et al., GCN 43469) using the AZT-33IK telescope of the Mondy observatory starting on 2026-01-20 (UT) 18:52:22 and 2026-01-21 (UT) 19:10:23, and the Zeiss-1000 of the SAO RAS starting on 2026-01-21 (UT) 03:05:44.
In the stacked frame of each observational epoch we do not detect the optical source reported previously (Fortin et al., GCN 43450; GCN 43455; Eyles-Ferris et al., GCN 43452; Moskvitin and Spiridonova, GCN 43463; Liu et al., GCN 43464; Ma et al., GCN 43466; Zheng et al., GCN 43468; Corcoran et al., GCN 43469; Bochenek and Perley, GCN 43472; Pankov et al., GCN 43476; Jin et al., GCN 43496). Preliminary photometry and observation details are listed below:
Date UT start t-T0 Exp. Filter Mag MagErr. UL Site/Telescope
(mid,days) (n*s) (3sigma)
2026-01-20 18:52:22 1.80804 45x120 I n/d n/d 22.3 Mondy/AZT-33IK
2026-01-21 03:05:44 2.13449 8*300 Ic n/d n/d 21.9 SAO RAS/Zeiss-1000
2026-01-21 19:10:23 2.82417 52*120 I n/d n/d 21.7 Mondy/AZT-33IK
Photometric data are based on nearby SDSS stars (I-magnitudes obtained using the 2005 Lupton transform) and not corrected for Galactic extinction.
GCN Circular 43496
Subject
EP260119a: Xinglong optical upper limit
Date
2026-01-22T03:29:52Z (21 days ago)
Edited On
2026-01-22T16:30:33Z (21 days ago)
From
Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) <xinglong@nao.cas.cn>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) <xinglong@nao.cas.cn>
Via
Web form
Junjie-Jin (NAOC), Haiyang-Mu (NAOC), Sen-Liu (NAOC), Pengliang-Du (NAOC),
Zhou-Fan (NAOC), Hong-Wu (NAOC) report:
Following the detection of EP260119a by EP-WXT (GCN Circular 43447,GCN Circular 43452), we observed the field of EP260119a using the 2.16-m
telescope at Xinglong Observatory, NAOC. We obtained 600s clear-band frames with a
median time of 2026-01-19 18:38:00 hr after the EP trigger.
No uncatalogued optical transient is detected in the stacked images within the 3 arcmin
EP/WXT error circle (GCN Circular 43447), down to 5-sigma limiting magnitudes of z ~
19.8(not good day with thin cloud and bad seeing), calibrated with Pan-STARRS sources in the field. Also there is no apparent brightening for the catalogued sources within the error circle. Based on the location of the report(GCN Circular 43452), the target was not observed.
GCN Circular 43476
Subject
EP260119A: Mondy I-Band Observations
Date
2026-01-20T18:05:21Z (23 days ago)
From
Nicolai Pankov at IKI <colinsergesen@gmail.com>
Via
Web form
N. Pankov (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI) report on behalf of IKI-GRB-FuN:
We observed the field of the EP260119a (Jiang et al., GCN 43447; Cheng et al., GCN 43449) at the redshift of z ~ 5.47 (Corcoran et al., GCN 43469) with the AZT-33IK 1.5-meter telescope of the Mondy observatory. We obtained 45x120 sec total exposure in the I-band, starting on 2026-01-19 at 17:18:42 UT.
The afterglow (Fortin et al., GCN 43450; GCN 43455; Eyles-Ferris et al., GCN 43452; Moskvitin & Spiridonova, GCN 43463; Liu et al., GCN 43464; Ma et al., GCN 43466; Zheng et al., GCN 43468; Corcoran et al., GCN 43469; Bochenek & Perley, GCN 43472) is clearly detected in the stacked image. The preliminary photometry and observation details are provided below:
Date UT start t-T0 Exp. Filter Mag MagErr. UL
(mid,days) (n*s) (3sigma)
2026-01-19 17:18:42 0.74299 45*120 I 20.87 0.11 22.2
The photometry is based on the same stars used by (Moskvitin & Spiridonova, GCN 43463) and has not been corrected for the Galactic extinction.
GCN Circular 43472
Subject
EP260119a: Liverpool Telescope optical follow-up observations
Date
2026-01-20T16:34:32Z (23 days ago)
From
A. Bochenek at Liverpool John Moores University <a.m.bochenek@2023.ljmu.ac.uk>
Via
Web form
A. Bochenek, D. A. Perley (LJMU), report:
We observed the field of EP 260119a (Jiang et al., GCN 43447, Cheng et al. GCN 43449, Jiang et al. GCN 43465) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 12x100s exposures in the SDSS r and i filters and 11x100s in SDSS z, starting at 2026-01-19 23:58:53 UT, approximately 24 hours after trigger.
We report detections in the stacked images in SDSS i and z filters at the position first reported by Fortin et al. GCN 43450 and Eyles-Ferris et al. GCN 43452, as well as a non-detection in the SDSS r filter:
MJD (mid) T_mid-T_0 Filter Mag. (AB)
61060.02484 24.37 h r >22.92
61060.03376 24.58 h i 22.06 ± 0.18
61060.04432 24.83 h z 20.85 ± 0.16
The photometry is consistent with measurements taken at similar time by Liu et al. GCN 43464. The photometry was obtained using nearby PanSTARRS secondary standards and was not corrected for extinction.
GCN Circular 43469
Subject
EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
Date
2026-01-20T09:45:18Z (23 days ago)
From
Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk>
Via
Web form
G. Corcoran (UCD), A. J. Levan (Radboud and Warwick), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), R. A. J. Eyles-Ferris (Leicester), P. G. Jonker (Radboud), A. L. Cabrera Lavers (GTC), A. M. García Rodríguez (GTC) report on behalf of a larger collaboration:
We observed the optical counterpart (Fortin et al., GCN 43450; Eyles-Ferris et al., GCN 43452; Moskvitin & Spiridonova, GCN 43463; Liu et al., GCN 43464; Ma et al., GCN 43466; Zheng et al., GCN 43468) of the Einstein Probe fast X-ray transient EP260119a (Jiang et al., GCNs 43447, 43465) using the Gran Telescopio Canarias (GTC) equipped with the OSIRIS+ spectrograph. Our observations consisted of 4 exposures of 1200 s each, using grism R1000R and covering the wavelength range 5200-10200 Å. The observation mid time was Jan 20.156 UT (27.5 hr after trigger).
In the acquisition image, the target is detected with an AB magnitude z = 21.06 +- 0.10 (mid time 26.8 hr after trigger), calibrated against nearby Pan-STARRS objects and not corrected for Galactic extinction.
A trace is well detected in the red part of our spectrum, with a sharp break around 7870 Å. We interpret this as the onset of the Lyman forest at z ~ 5.47. The sharpness of the break indicates a low HI column density. No clear metal lines are identified in the currently available (preliminary) reduction of the spectra. Our spectroscopic measurement of the redshift is in broad agreement with, and refines, the photometric determination reported by COLIBRÍ (Fortin et al., GCN 43455).
GCN Circular 43468
Subject
EP260119a: KAIT optical observations
Date
2026-01-20T08:08:36Z (23 days ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
email
WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and
Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, observed the field of EP260119a (Jiang et al.,
GCN 43447; Cheng et al., GCN 43449; Jiang et al., GCN 43465) from
8.13 to 11.55 hours after the burst. A set of 150x60s clear
(roughly R) filter images were obtained. We clearly detected the
optical afterglow (Fortin et al., GCN 43450; Eyles-Ferris et al.,
GCN 43452; Lipunov et al., GCN 43454; Fortin et al., GCN 43455;
Moskvitin & Spiridonova, GCN 43463; Liu et al., GCN 43464; Ma et al.,
GCN 43466) in our coadd image. We measure its brightness to be
21.6 +/- 0.2 mag (Vega) at a mid time of 9.84 hours after the burst.
GCN Circular 43466
Subject
EP260119a: SVOM/VT optical observation
Date
2026-01-20T03:46:52Z (23 days ago)
From
Yinuo Ma <mayn@bao.ac.cn>
Via
Web form
Y. N. Ma, L. P. Xin, Y. L. Qiu, C. Wu, H. L. Li, Z. H. Yao, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team.
SVOM/VT performed a Target of Opportunity observation of EP260119a detected by EP/WXT (Jiang et al., GCN 43447; Cheng et al., GCN 43449; Jiang et al., GCN 43465). SVOM/VT began observing the field at 2026-01-19T09:38:01 UTC, 9.404 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
With X-band data available, the optical counterpart (Fortin et al., GCN 43450; Eyles-Ferris et al., GCN 43452; Lipunov et al., GCN 43454; Fortin et al., GCN 43455; Moskvitin & Spiridonova, GCN 43463; Liu et al., GCN 43464) was only detected in VT_R band. The magnitudes are:
mid time (h) | exposure time (s) | band | mag (AB)
-------------|-------------------|------|----------------
10.704 | 65*50 | VT_B | > 23.4
10.656 | 61*50 | VT_R | 20.86+-0.08
Our photometry was not corrected for Galactic extinction.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.
GCN Circular 43465
Subject
EP260119a: update of EP-FXT follow-up observation
Date
2026-01-20T03:17:16Z (23 days ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Y. H. Jiang (NJU), D. Zhu, K.J. Zhang ,Y.H. Cheng (SWIFAR,YNU), R. X. Hu (WHU)，H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team:
EP-FXT performed a follow-up observation of EP260119a (detected by EP-WXT, GCN #43447; and followed by COLIBRI telescope, LCO telescope, MASTER-Net observations, SAO RAS and NOT; GCN #43450, GCN #43455, GCN #43452, GCN #43454, GCN #43463, GCN #43464) about 7.5 hours after the WXT detection, with an exposure time of 6.0 ks. The FXT telemetry data show that an uncatalogued source was detected within the WXT error circle at R.A. = 158.1047, DEC = 65.4975 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic, reported by Cheng et al ., GCN #43449). The FXT X-ray spectrum of this uncatalogued source can be fitted with an absorbed powerlaw with a hydrogen column density fixed at the Galactic value of 1.20 x 10^20 cm^-2 and a photon index of 1.99 (+/- 0.13). The derived unabsorbed 0.5-10 keV flux is approximately 5.69 (+0.60/-0.55) x 10^-13 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters.
Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).
GCN Circular 43464
Subject
EP260119a: NOT optical observations
Date
2026-01-20T02:54:49Z (23 days ago)
From
liuxing@nao.cas.cn
Via
Web form
X. Liu, S.Q. Jiang, J. An, L.B. He, Z.P. Zhu, D. Xu (NAOC), S.Y. Fu (HUST), J.P.U. Fynbo (DAWN/NBI), K. Valeckas (NOT) report on behalf of a large collaboration:
We observed the field of EP260119a (Jiang et al., GCN43447; Cheng et al., GCN43449) using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 23:11:51.27 UT on 2026-01-19, i.e., 22.97 hr after the EP trigger, and we obtained 6 x 300 s frames in the Sloan i- and z- bands, respectively .
The reported optical counterpart (Fortin et al., GCN43450; GCN 43455; Eyles-Ferris et al., GCN 43454; Moskvitin et al., GCN 43453) was detected in our stacked images in both i- and z- bands. Preliminary photometric results are as follows:
T-mid (hr) | Filter | Exposure | Mag
23.80 | i | 6x300s | 21.85 +/- 0.06
23.24 | z | 6x300s | 20.94 +/- 0.08
calibrated with nearby Pan-STARRS1 DR2 stars without the Galactic extinction correction.
GCN Circular 43463
Subject
EP260119a: SAO RAS optical observations
Date
2026-01-20T00:19:23Z (23 days ago)
From
Alexander Moskvitin at SAO RAS <mosk@sao.ru>
Via
Web form
A. S. Moskvitin and O. I. Spiridonova (SAO RAS)
report on behalf of GRB follow-up team.
We observed the field of the EP260119a (Jiang et al., GCN 43447;
Cheng et al., GCN 43449) with the Zeiss-1000 1m telescope
of the SAO RAS equipped with the CCD photometer. We obtained
8 x 300 sec in Ic band on on Jan. 19, 21:33:52--22:18:23 UT
(t_mid - T0 = 0.90439 days).
The OT (Fortin et al., GCN 43450; GCN 43455; Eyles-Ferris et al.,
GCN 43452) is clearly detected in our stacked frame
with the brightness of I = 20.8 +/- 0.1 (I_lim = 22.0).
This preliminary photometry is based on several nearby SDSS stars
(I-magnitudes obtained with Lupton 2005 transformation)
and is not corrected for the Galactic extinction.
Magnitudes is in Vega system.
GCN Circular 43455
Subject
EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
Date
2026-01-19T18:02:49Z (24 days ago)
From
Alan Watson at UNAM <alan@astro.unam.mx>
Via
Web form
Francis Fortin (IRAP), Leonardo García García (UNAM), Camila Angulo (UNAM), Nikos Mandarakas (LAM), Alan M. Watson (UNAM), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Asuka Kuwata (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report:
We imaged the field of EP260119a (Jiang et al., GCN Circ. 43447; Cheng et al., GCN CIrc. 43449) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-19 09:00 to 13:37 UTC (from 8.7 to 13.4 hours after the trigger) and obtained 105, 53, 97, and 32 minutes of exposure in the r, i, z, and y filters.
The data were reduced and coadded with the COLIBRÍ ASU pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction.
Our longer time interval and multi-filter photometry allows us to estimate the decay index and the photometric redshift of the optical counterpart reported by ourselves in Fortin et al. (GCN Circ. 43450) and confirmed by Eyles-Ferris et al. (GCN Circ 43452).
In the z band, we see a shallow decay with a temporal index of -0.44 +/- 0.19.
The counterpart is detected in all four bands. After correcting for the Galactic foreground extinction corresponding to a reddening of E(B-V) = 0.011 mag (Schlafly & Finkbeiner 2011) and fitting a power-law model to the rizy-bands using a no dust extinction curve, we derive a photometric redshift of z = 5.62 with formal errors of +0.02-0.03 (1-sigma c.l.).
We caution that our magnitudes are not strictly simultaneous, but nevertheless the break from z to i to r is much stronger than can be accounted for by this effect.
We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams.
COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.
GCN Circular 43454
Subject
EP260119a: Global MASTER-Net observations report
Date
2026-01-19T17:36:27Z (24 days ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko,
G.Antipov, A.Sankovich, Yu.Tselik, 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.Sosnovskij (CrAO),
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 [1] located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the EP260119a ( EP Team et al., GCN 43447) errorbox 32012 sec after notice time and 60248 sec after trigger time at 2026-01-19 16:57:56 UT, with upper limit up to 20.4 mag. The observations began at zenith distance = 26 deg. The sun altitude is -59.1 deg.
The galactic latitude b = 46 deg., longitude l = 143 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3107348
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
60279 | 2026-01-19 16:57:56 | MASTER-Tunka | (10h 31m 16.45s , +66d 08m 29.3s) | C | 60 | 20.3 |
60279 | 2026-01-19 16:57:56 | MASTER-Tunka | (10h 29m 47.72s , +66d 16m 01.1s) | C | 60 | 20.0 |
60352 | 2026-01-19 16:59:09 | MASTER-Tunka | (10h 31m 09.89s , +66d 07m 36.5s) | C | 60 | 20.4 |
60352 | 2026-01-19 16:59:09 | MASTER-Tunka | (10h 29m 41.26s , +66d 15m 08.6s) | C | 60 | 20.0 |
60427 | 2026-01-19 17:00:24 | MASTER-Tunka | (10h 31m 09.54s , +66d 08m 35.2s) | C | 60 | 20.3 |
60427 | 2026-01-19 17:00:24 | MASTER-Tunka | (10h 29m 40.79s , +66d 16m 07.0s) | C | 60 | 20.0 |
60507 | 2026-01-19 17:01:44 | MASTER-Tunka | (10h 31m 15.00s , +66d 07m 33.2s) | C | 60 | 20.4 |
60507 | 2026-01-19 17:01:44 | MASTER-Tunka | (10h 29m 46.20s , +66d 15m 05.6s) | C | 60 | 19.9 |
60580 | 2026-01-19 17:02:57 | MASTER-Tunka | (10h 31m 07.97s , +66d 06m 32.0s) | C | 60 | 20.4 |
60580 | 2026-01-19 17:02:57 | MASTER-Tunka | (10h 29m 39.21s , +66d 14m 03.9s) | C | 60 | 19.9 |
60653 | 2026-01-19 17:04:11 | MASTER-Tunka | (10h 31m 13.12s , +66d 06m 55.4s) | C | 60 | 20.4 |
60653 | 2026-01-19 17:04:11 | MASTER-Tunka | (10h 29m 44.32s , +66d 14m 27.1s) | C | 60 | 20.0 |
60729 | 2026-01-19 17:05:27 | MASTER-Tunka | (10h 31m 10.06s , +66d 08m 03.1s) | C | 60 | 20.4 |
60729 | 2026-01-19 17:05:27 | MASTER-Tunka | (10h 29m 41.17s , +66d 15m 34.4s) | C | 60 | 20.0 |
60815 | 2026-01-19 17:06:52 | MASTER-Tunka | (10h 31m 09.77s , +66d 06m 47.2s) | C | 60 | 20.3 |
60815 | 2026-01-19 17:06:52 | MASTER-Tunka | (10h 29m 40.81s , +66d 14m 18.8s) | C | 60 | 19.9 |
60887 | 2026-01-19 17:08:05 | MASTER-Tunka | (10h 31m 13.15s , +66d 08m 15.5s) | C | 60 | 20.4 |
60887 | 2026-01-19 17:08:05 | MASTER-Tunka | (10h 29m 44.02s , +66d 15m 47.0s) | C | 60 | 20.0 |
60961 | 2026-01-19 17:09:18 | MASTER-Tunka | (10h 31m 05.28s , +66d 07m 24.6s) | C | 60 | 20.4 |
60961 | 2026-01-19 17:09:18 | MASTER-Tunka | (10h 29m 36.21s , +66d 14m 55.7s) | C | 60 | 20.0 |
61036 | 2026-01-19 17:10:34 | MASTER-Tunka | (10h 31m 05.02s , +66d 08m 23.0s) | C | 60 | 20.4 |
61036 | 2026-01-19 17:10:34 | MASTER-Tunka | (10h 29m 35.82s , +66d 15m 54.2s) | C | 60 | 20.0 |
61111 | 2026-01-19 17:11:48 | MASTER-Tunka | (10h 31m 11.19s , +66d 07m 21.5s) | C | 60 | 20.4 |
61111 | 2026-01-19 17:11:49 | MASTER-Tunka | (10h 29m 41.99s , +66d 14m 52.8s) | C | 60 | 19.9 |
61186 | 2026-01-19 17:13:04 | MASTER-Tunka | (10h 31m 05.60s , +66d 06m 19.1s) | C | 60 | 20.4 |
61186 | 2026-01-19 17:13:04 | MASTER-Tunka | (10h 29m 36.47s , +66d 13m 50.5s) | C | 60 | 20.0 |
61262 | 2026-01-19 17:14:19 | MASTER-Tunka | (10h 31m 09.69s , +66d 06m 22.9s) | C | 60 | 20.4 |
61262 | 2026-01-19 17:14:19 | MASTER-Tunka | (10h 29m 40.43s , +66d 13m 54.9s) | C | 60 | 20.0 |
61335 | 2026-01-19 17:15:33 | MASTER-Tunka | (10h 31m 06.90s , +66d 07m 57.6s) | C | 60 | 20.4 |
61335 | 2026-01-19 17:15:33 | MASTER-Tunka | (10h 29m 37.54s , +66d 15m 48.4s) | C | 60 | 19.7 |
61409 | 2026-01-19 17:16:47 | MASTER-Tunka | (10h 31m 06.53s , +66d 06m 43.7s) | C | 60 | 20.3 |
61409 | 2026-01-19 17:16:47 | MASTER-Tunka | (10h 29m 37.16s , +66d 14m 35.6s) | C | 60 | 19.9 |
61483 | 2026-01-19 17:18:00 | MASTER-Tunka | (10h 31m 08.49s , +66d 07m 46.8s) | C | 60 | 20.3 |
61483 | 2026-01-19 17:18:00 | MASTER-Tunka | (10h 29m 38.92s , +66d 15m 38.1s) | C | 60 | 20.0 |
61558 | 2026-01-19 17:19:15 | MASTER-Tunka | (10h 31m 03.24s , +66d 07m 11.2s) | C | 60 | 20.4 |
61558 | 2026-01-19 17:19:16 | MASTER-Tunka | (10h 29m 33.66s , +66d 15m 02.3s) | C | 60 | 20.0 |
61631 | 2026-01-19 17:20:28 | MASTER-Tunka | (10h 31m 03.39s , +66d 08m 09.2s) | C | 60 | 20.4 |
61631 | 2026-01-19 17:20:28 | MASTER-Tunka | (10h 29m 33.60s , +66d 16m 00.6s) | C | 60 | 19.9 |
61703 | 2026-01-19 17:21:41 | MASTER-Tunka | (10h 29m 38.69s , +66d 14m 59.2s) | C | 60 | 20.0 |
61703 | 2026-01-19 17:21:41 | MASTER-Tunka | (10h 31m 08.49s , +66d 07m 07.4s) | C | 60 | 20.4 |
61777 | 2026-01-19 17:22:55 | MASTER-Tunka | (10h 31m 01.86s , +66d 06m 05.4s) | C | 60 | 20.4 |
61777 | 2026-01-19 17:22:55 | MASTER-Tunka | (10h 29m 32.07s , +66d 13m 57.0s) | C | 60 | 19.9 |
61852 | 2026-01-19 17:24:09 | MASTER-Tunka | (10h 31m 08.12s , +66d 06m 25.5s) | C | 60 | 20.3 |
61852 | 2026-01-19 17:24:09 | MASTER-Tunka | (10h 29m 38.21s , +66d 14m 17.5s) | C | 60 | 19.9 |
61925 | 2026-01-19 17:25:23 | MASTER-Tunka | (10h 31m 04.08s , +66d 07m 59.9s) | C | 60 | 20.4 |
61926 | 2026-01-19 17:25:23 | MASTER-Tunka | (10h 29m 34.06s , +66d 15m 51.6s) | C | 60 | 19.9 |
61999 | 2026-01-19 17:26:36 | MASTER-Tunka | (10h 31m 03.79s , +66d 06m 09.1s) | C | 60 | 20.4 |
61999 | 2026-01-19 17:26:36 | MASTER-Tunka | (10h 29m 33.75s , +66d 14m 01.0s) | C | 60 | 19.9 |
62072 | 2026-01-19 17:27:49 | MASTER-Tunka | (10h 31m 06.81s , +66d 07m 44.6s) | C | 60 | 20.4 |
62072 | 2026-01-19 17:27:49 | MASTER-Tunka | (10h 29m 36.65s , +66d 15m 36.3s) | C | 60 | 20.0 |
62145 | 2026-01-19 17:29:03 | MASTER-Tunka | (10h 30m 59.37s , +66d 06m 57.6s) | C | 60 | 20.4 |
62145 | 2026-01-19 17:29:03 | MASTER-Tunka | (10h 29m 29.23s , +66d 14m 49.2s) | C | 60 | 20.0 |
62225 | 2026-01-19 17:30:23 | MASTER-Tunka | (10h 31m 00.13s , +66d 07m 55.9s) | C | 60 | 20.4 |
62225 | 2026-01-19 17:30:23 | MASTER-Tunka | (10h 29m 29.89s , +66d 15m 47.5s) | C | 60 | 19.9 |
62299 | 2026-01-19 17:31:37 | MASTER-Tunka | (10h 31m 06.28s , +66d 06m 54.1s) | C | 60 | 20.4 |
62299 | 2026-01-19 17:31:37 | MASTER-Tunka | (10h 29m 36.01s , +66d 14m 45.6s) | C | 60 | 20.0 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
[1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp.
http : // www.pereplet.ru/lipunov/625.html
GCN Circular 43452
Subject
EP260119a: LCO optical observations
Date
2026-01-19T13:02:37Z (24 days ago)
From
Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk>
Via
Web form
R. A. J. Eyles-Ferris (Leicester), J. A. Quirola-Vasquez (Radboud), G. Corcoran (UCD), D. B. Malesani (DAWN-NBI and Radboud), A. van Hoof (Radboud), A. Martin-Carrillo (UCD), P. G. Jonker (Radboud), A. J. Levan (Radboud and Warwick) report on behalf of a larger group:
We observed the field of the fast X-ray transient EP260119a (Jiang et al., GCN 43447; Cheng et al., GCN 43449) using an LCO 1m telescope located at the McDonald Observatory (Texas, USA) equipped with the SINISTRO instrument. A series of 3x300 s exposures was taken in each of the SDSS-r and SDSS-z filters, starting on 2026-01-19 at 09:40:45 UT (9.45 hr after the trigger).
The optical counterpart discovered by COLIBRÍ (Fortin et al., GCN 43450) is detected in our images, with magnitudes:
r = 22.83 +- 0.33 (9.54 hr after trigger)
z = 20.26 +- 0.13 (9.81 hr after trigger)
These values are in the AB system, are calibrated against the Pan-STARRS survey, and are not corrected for Galactic extinction. Our measurements confirm the red r-z color of the afterglow (Fortin et al., GCN 43450).
No host galaxy is detected in the r band in a stack of archival CFHT images, down to a limiting magnitude r > 24.5.
GCN Circular 43450
Subject
EP260119a: COLIBRÍ optical counterpart candidate
Date
2026-01-19T11:36:14Z (24 days ago)
From
F. Fortin at IRAP <ffortin.sci.edu@gmail.com>
Via
Web form
Francis Fortin (IRAP), Leonardo García García (UNAM), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM), Fredd Sánchez Álvarez (UNAM), and Antonio de Ugarte Postigo (LAM):
We imaged the field of EP260119a (Jiang et al., GCN Circ. 43447) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-01-19T09:00:10 to 09:43:40 UTC (from 8.7 to 9.5 hours after the trigger) and obtained 32 minutes of simultaneous exposure in the r and z filters.
The data were reduced and coadded with the COLIBRÍ pipelines and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction.
We detect an uncatalogued source (revealed by image subtraction using PanSTARRS as template) and consistent with the WXT 2.3 arcmin error circle and located 8 arcsec away from the FXT position (20 arcsec error circle, Cheng et al., GCN Circ 43449) at:
RA(J2000) = 10:32:24.4 = 158.1018 degrees
Dec(J2000) = +65:29:44.2 = +65.4956 degrees
with an uncertainty of 0.5 arcsec.
The preliminary magnitudes for this source are:
r = 23.02 +/- 0.14
z = 20.08 +/- 0.03
This source is a good candidate for being the optical counterpart of EP260119a, and we encourage further observations to confirm its nature.
We also note that the candidate is very red, which could indicate a source located at high redshift. Further observations with COLIBRÍ are ongoing.
We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams.
COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.
GCN Circular 43449
Subject
EP260119a: preliminary result from the EP-FXT observation
Date
2026-01-19T09:24:28Z (24 days ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Y.H. Cheng (SWIFAR,YNU), Y. H. Jiang (NJU), D. Zhu, K.J. Zhang (SWIFAR,YNU), R. X. Hu (WHU)，H. Sun (NAO, CAS) report on behalf of the Einstein Probe team
We performed a follow-up observation of EP260119a (detected by EP-WXT Jiang et al ., GCN #43447 ), with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation began at 2026-01-19T07:21:31 UTC, about 7 hours after the detection.
The FXT onboard alert shows that one uncatalogued source was detected by both FXT-A and FXT-B. The position of the source is R.A. = 158.1047 deg, DEC = 65.4975 deg, (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). The estimated flux in the 0.5-10 keV band inferred from the alert information is around 5.0 x 10^-13 erg/cm^2/s.
More information will be updated when the telemetry data is received.
Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES.
GCN Circular 43447
Subject
EP260119a: EP-WXT detection of a fast X-ray transient
Date
2026-01-19T08:03:26Z (24 days ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Y. H. Jiang (NJU), D. Zhu, K.J. Zhang ,Y.H. Cheng (SWIFAR,YNU), R. X. Hu (WHU)，H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team:
We report on the detection of a fast X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP260119a. The source has a signal-to-noise ratio of 7.5. But the total number of counts is insufficient to trigger the WXT on-board trigger unit. The event started at 2026-01-19T00:13:48 (UTC) and lasted for almost 300 seconds. The WXT position of the source is R.A. = 158.082 deg, DEC = 65.505 deg (J2000) with an uncertainty of 2.3 arcmin in radius (90% C.L. statistical and systematic).
The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a photon index of 1.8(-/+0.6) and with a fixed galactic hydrogen column density of 1.2 x 10^20 cm^-2. The derived average unabsorbed 0.5-4 keV flux is 4.4 (-1.3/+1.8) x 10^-11 erg/s/cm^2. The peak flux in the 0.5-4 keV band reaches 4.8 x 10^-10 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters.
The stellar flare origin can not be fully ruled out. A follow-up observation with EP-FXT has been scheduled.
Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).