Gamma-ray Burst 250219A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN Circular #39376
F. Daigne, M. Gnaoui (IAP), N. Dagoneau (CEA), S. Guillot, M. Brunet (IRAP), C.W. Wang (IHEP) on behalf of the SVOM mission team.
At 2025-02-19T15:52:48 UTC (Tb) SVOM/ECLAIRs triggered on the gamma-ray burst GRB 250219A (SVOM burst-id sb25021904). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network.
The burst was only detected by the Image Trigger (IMT), from which we received 2 alerts. IMT provided the alert with the best signal-to-noise-ratio (SNR) of 14.57 in the [5-8] keV energy band over a time window of 40.96 seconds starting at Tb.
The light curve showed a first episode of about 10 s, followed by a possibly related second episode 130 s later, with a duration of about 50 s.
The localization of the best alert is R.A., Dec 173.278, 22.684 degrees:
```
RA (J2000) = 11h33m06.69s
Dec (J2000) = 22d41m01.24s
```
with a 90% C.L. radius of 5.65 arcmin (including systematic error of 2 arcmin added in quadrature).
No immediate slew was performed on this burst. A SVOM ToO has been requested.
The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe.
The Burst Advocate (BA) on shift for this burst is Frédéric Daigne: daigne@iap.fr. Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst.
GCN Circular #39377
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the SVOM/ECLAIRs GRB 250219A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021785
Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the SVOM/ECLAIRs event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular #39379
J. A. Kennea (PSU), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB), D.N. Burrows (PSU), M. A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected burst GRB 250219A, collecting 323 s of Photon Counting (PC) mode data between T0+4.9 ks and T0+11.3 ks.
One uncatalogued X-ray source has been detected within the estimated 3-sigma SVOM/ECLAIRs error region (557 arcsec), it is below the RASS limit and shows no definitive signs of fading. Therefore, at the present time we cannot confirm this as the afterglow. Details of this source are given below:
Source 1:
```
  RA (J2000.0):  173.3707  =  11:33:28.97
  Dec (J2000.0): +22.7056  =  +22:42:20.2
  Error: 5.2 arcsec (radius, 90% conf.)
  Count-rate: 0.072 +/- 0.018 ct s^-1	
  Distance: 317 arcsec from SVOM/ECLAIRs position.
  Flux: (2.19 +/- 0.54)e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)
```
The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00021785.
This circular is an official product of the Swift-XRT team.
GCN Circular #39380
L.P. Xin, Y.L. Qiu, H.L. Li, C. Wu, Z.H. Yao, Y. N. Ma, X.H. Han, H.B. Cai, J. Wang, Y. Xu, J.Y. Wei (NAOC), R.Z. Li(YNAO), F. Daigne, M. Gnaoui (IAP) report on behalf of the SVOM team:
The SVOM/VT conducted a ToO follow-up observations of the GRB 250219A (Daigne et al., GCN 39376) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously.
With the X band downlinked data, an uncatalogued optical source was clearly detected within the errorbox of Swift/XRT (Kennea et al., GCN 39379) in VT_R and VT_B stacked images, compared to the DESI catalogues.
The position is RA= 173.37166 deg, DEC= 22.70598 deg, J2000, corresponds to
```
RA = 11:33:29.2
DEC = +22:42:21.5
Error=0.5 arcsec
```
The source is brightening at the first phase during our observations and the brightness was estimated to be 22.1+/-0.2 mag in AB magnitude in VT_R, and 23.3+/-0.3 mag in AB magnitude in VT_B, at the mid time of 6.71 hours post the burst, with an exposure time of 16*100 seconds.
More deep follow-ups are encouraged.
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 #39381
Edoardo P. Lagioia, Yu Pan, Xiangkun Liu, Yaosong Yu, Guowang Du, Brajesh Kumar, Yuan Fang, Jinghua Zhang, Xinlei Chen, Xingzhu Zou, Yuanpei Yang (all SWIFAR, YNU), Xuhui Han, Pinpin Zhang, Liping Xin, Chao Wu, Jianyan Wei (all NAOC), Xiaowei Liu (SWIFAR, YNU) report on behalf of the Mephisto Team:
The field of GRB 250219A detected by SVOM/ECLAIRs (Daigne et al., GCN 39376) and followed-up by Swift-XRT (Kennea et al. GCN 39379) was observed with the 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. Simultaneous uvgr band photometric observations were conducted starting from 17:08:52 2025-02-19 UT (~1.26 hr after the trigger) and 4 frames with 120s exposure times were taken. There is no detection of the optical candidate (Xin et al. GCN 39380) in the stacked images of uvgr bands. The preliminary photometry and 3 sigma upper limits are listed below.
```
Start_Time(UT)      | Band | Exp(s) | LimMag (AB)
---------------------------|--------|------------
2025-02-19T17:18:46 | u    | 120*4  | >22.4
2025-02-19T17:08:52 | v    | 120*4  | >22.2
2025-02-19T17:18:46 | g    | 120*4  | >22.8
2025-02-19T17:08:52 | r    | 120*4  | >22.8
```
-------------------------------------------------------------------------------------------------
Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6-m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. It provides real-time, high-quality colors of stellar objects. The on-site telescope assemblage and commissioning were carried out in September 2022. The first light in all three channels was achieved on 2023 December 21.
-------------------------------------------------------------------------------------------------
GCN Circular #39382
Francesco Magnani (CPPM), Alan M. Watson (UNAM), Sarah Antier (OCA), Jean-Grégoire Ducoin (CPPM), Diego López-Cámara (UNAM), Benjamin Schneider (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Jean-Luc Atteia (IRAP), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), and Antonio de Ugarte Postigo (LAM) report:
We imaged the field of the SVOM/ECLAIRs GRB 250219A (Daigne et al., GCN Circ. 39376) with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico.
We observed from 2025-02-20 05:19 to 07:41 UTC (13.47 to 15.85 hours after the trigger) and obtained 90 minutes of exposure in the i filter. The data were coadded with custom software and analyzed in STDWeb/STDPipe (Karpov 2021), with photometric calibration against Pan-STARRS DR1. Our photometry is in the AB system and is not corrected for Galactic extinction.
At the position of the optical afterglow found by Xin et al. (GCN Circ. 39380), close to the uncataloged Swift/XRT source reported by Kennea et al. (GCN Circ. 39379), we detect a source with
i = 23.53 +/- 0.21
We cannot yet confirm fading, as none of the previously reported photometry is in the i filter (Xin et al., GCN Circ. 39380; Lagioia et al., GCN Circ. 39381).
Further observations are planned.
We warmly thank the COLIBRÍ and DDRAGO engineering teams and the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir.
GCN Circular #39383
S. Y. Fu (NAOC), J. T. Palmerio (CEA/Irfu), D. B. Malesani (DAWN/NBI and Radboud Univ.), L. Cotter (UCD), D. Xu (NAOC), B. Schneider (LAM), B. N. Hauptmann (NOT and DTU Space), A. M. Kadela (NOT and NBI), report on behalf of a larger collaboration:
We observed the optical afterglow candidate (Xin et al., GCN 39380; Magnani et al., GCN 39382; see also Kennea et al., GCN 39379) of the SVOM/ECLAIRs GRB 250219A (Daigne et al., GCN 39376). Observations were carried out using the ALFOSC instrument mounted on the Nordic Optical Telescope (NOT). We obtained 3 x 300 s Sloan r-band frames at a median time of 10.16 hr post-burst and 5 x 200 s Sloan z-band frames at a median time of 10.46 hr post-burst.
In the stacked r-band image, the afterglow is weakly detected, at coordinates
```
R.A. (J2000) = 11:33:29.18
Dec. (J2000) = +22:42:21.85
```
with an uncertainty of ~0.3 arcsec, which is consistent with the SVOM/VT counterpart position (Xin et al, GCN 39380). The source had r ~ 23.6 +/- 0.3 mag (AB), calibrated against nearby objects from the Pan-STARRS catalog. The decay between the NOT and the SVOM/VT epochs (see also Magnani et al., GCN 39382) confirms the source is the afterglow of the burst.
The source is not detected in the stacked z-band image, down to a limiting magnitude of z ~ 22.2 mag (AB), again calibrated against Pan-STARRS.
GCN Circular #39384
C. Adami (LAM/Pytheas/AMU), B. Schneider (LAM), M. Dennefeld (IAP/CNRS/Sorbonne U.), J. P. Palmerio (CEA/Irfu), E. Le Floc'h (CEA/Irfu), D. Turpin (CEA/Irfu), S. Basa (UAR Pytheas) report on behalf of a larger collaboration:
We observed the field of the GRB 250219A (Daigne et al., GCN 39376) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 7 exposures (1x360s, 1x720s and 5x600s) in the r-band starting at 01:11:32 UT on 2025-02-20 (9.3h after the trigger).
In the stacked image, we do not detect any new source at the XRT source #1 position (Evans et al., GCN 39377) down to the following 3-sigma limit:
r > 22.68 mag AB
This value is consistent with previously reported detections or upper limits on the optical afterglow (Xin et al., GCN 39380; Lagioia et al., GCN 39381; Magnani et al., GCN 39382; Fu et al., GCN 39383).
The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitude is not corrected for Galactic extinction.
We acknowledge the excellent support from Observatoire de Haute-Provence and in particular Stephane Favard, Yasmine Davis and Alix Freckelton for the MISTRAL observations.
GCN Circular #39385
A.A. Breeveld (UCL-MSSL) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of the SVOM/ECLAIRS-detected burst GRB 250219A (Daigne et al., GCN Circ. 39376) 5.1 ks after the trigger. The afterglow reported by Kennea et al. (GCN Circ. 39379), Xin et al. (GCN Circ. 39380), Magnani et al. (GCN Circ. 39382) and Fu et al. (GCN Circ. 39383) is not detected in the U-band exposures.
Preliminary 3-sigma upper limit using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial summed exposure is:
Filter T_start(s) T_stop(s) Exp(s) Mag
u 5097 11297 330 >20.1
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.016 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #39407
D. Turpin (CEA-Saclay/Irfu), D. Marchais (KNC), M. Freeberg (KNC), C. Andrade(UMN), S. Antier (OCA), M. Coughlin (UMN),S. Karpov (FZU), I. Tosta e Melo (UniCT-DFA), P. Hello (IJCLAB), P-A Duverne (APC), T. Pradier (Unistra/IPHC), N. Guessoum (AUS) on behalf of the GRANDMA/Kilonova-Catcher collaboration:
We observed the field of GRB 250219A (Daigne et al., GCN 39376) detected by SVOM/ECLAIRs with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with the T-CAT 0.4m telescope at Crous des Gats Observatory (Cintegabelle, France) and the 0.43m CDK telescope at Alnitak Observatory (Spain) starting from TGRB + 5.8hr.
In our stacked frames, we do not detect any optical afterglow at the position reported by Swift/XRT (Kennea et al., GCN 39379), SVOM/VT (Xin et al., GCN 39380) and COLIBRÍ (Magnani et al., GCN 39382). We obtain the following 5-sigma (Vega) upper limits:
```
+---------------+-----------+--------+---------+-----------+
| Tmid-TGRB (hr)| Exp (s)   | Filter | Mag U.L.| Instrument|
+===============+===========+========+=========+===========+
| 6.6           | 119 x 32s | Rc     | 20.7    | T-CAT     | 
| 6.6           | 119 x 32s | V      | 21.3    | T-CAT     | 
| 6.8           | 10 x 180s | Rc     | 20.9    | 0.43m CDK |
| 8.5           | 102 x 32s | Rc     | 20.8    | T-CAT     |
| 8.5           | 102 x 32s | V      | 21.4    | T-CAT     |
+---------------+-----------+--------+---------+-----------+
```
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.
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 #39419
T. Komesh (NU), Z. Abdullayev (NU), Z. Maksut (NU), D. Berdikhan (NU), B. Grossan (UCB, NU), M. Krugov (FAI) and E. Abdikamalov (NU) report on behalf of the Energetic Cosmos Laboratory:
We imaged the field of GRB 250219A with the Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) starting at 21:54:17 UT on 2025-02-19, 6.0 hours after the SVOM/ECLAIRs trigger (F. Daigne et al., GCN 39376). Observations were made in clear conditions. No source consistent with the XRT (J. A. Kennea et al., GCN 39379) was detected. We report the following results:
```
start time    t-t0 (minute)  end time    UL g'   UL r'  exposure_time (s)
------------ --------------------------------------------------
21:54:17	  361     21:55:17	 19.29   19.09 	  60
21:58:38          365     22:02:38	 19.57   19.49	  240
```
t is the middle time, t0 is the SVOM/ECLAIRs trigger time, t-t0 is given in minutes. UL gives the 5 sigma upper limit sensitivity in magnitudes, for images of the given exposure time. Calibration was done with 4 Pan-STARRS catalog stars on our images. No color or other corrections were applied to the values above.
-----------------------------------------------
```
NU = Nazarbayev University, Astana, Kazakhstan
UCB = University of California, Berkeley, USA
FAI = Fesenkov Astrophysical Institute, Kazakhstan
```
This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP26103591). The NUTTelA-TAO Team acknowledges the support of the staff of the Assy-Turgen Astrophysical Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical Institute, Almaty, Kazkhstan.
GCN Circular #39456
D. Turpin (CEA), P. Y. Han, C. X. Zhang (HUST), J. Yang (NJU), X. Tian (GXU), D. F. Hu (PMO, CAS), W. Chen (NAO, CAS), J. Guan, C. K. Li, Y . Chen, S. M. Jia, W. W. Cui, D. W. Han, W. Li, C. Z. Liu, F . J. Lu, L. M. Song, J. Wang, J. J. Xu, J. Zhang, S. N. Zhang, H. S. Zhao, X. F . Zhao (IHEP , CAS), Y . Liu, C. C. Jin, C. Zhang, Z. X. Ling (NAOC,CAS), B. Cordier (CEA) on behalf of the SVOM and Einstein Probe teams
We performed a follow-up observation of GRB 250219A (Daigne et al., GCN 39376) with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation started at 2025-02-21T07:04:16 (T-TGRB ~ 1.63 days) for about 3ks of exposure in total.
An uncatalogued X-ray source is detected by both FXT-A and FXT-B at the position of the x-ray afterglow candidate reported by Swift/XRT (Kennea et al., GCN 39379). This position is also consistent with the optical afterglow detected by SVOM/VT (Xin et al., GCN 39380), COLIBRÍ (Magnani et al. GCN 39382) and the NOT (Fu et al., GCN 39383).
A preliminary analysis shows that the spectrum can be fitted with an absorbed power law with nH=1.53*10^20 cm^-2 and a photon index of 1.53 (-0.68/+0.70) . The observed flux in the 0.3-10.0 keV is 4.4 (+2.2/-1.1)*10^-13 erg/s/cm^2. Compared to the Swift/XRT epoch Kennea et al., GCN 39379), the observed source flux has faded by almost one order of magnitude with a temporal slope alpha~-0.56.
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 #39595
Zhe Kang (CHO), F. Daigne (IAP), M. Gnaoui (IAP), Liping Xin(NAOC), Xuhui Han(NAOC), Chao WU (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 250219A (SVOM/ECLAIRs burst-id:sb25021904, Daigne et al. GCN 39376) starting at 2025-02-19T16:03:29 UT, ~10.68 mins after the burst trigger with C-GFT. A series of g, r and i band images were obtained with exposure time of 10s for each frame. No source consistent with the XRT (Kennea et al., GCN 39379; Turpin et al., GCN 39456) was detected. The optical counterpart (Xin et al., GCN 39380; Magnani et al., GCN 39382; Fu et al., GCN 39383; ) was not detected in our images. The upper limit at early phase are,
```
(T-T0)_mid(sec) exptime(s)  limiting_mag(3sigma)  band
------------------------------------------------------
 678      6x10s  >19.57 (6x10s)    i
1013      6x10s  >20.11 (6x10s)    g
1102      6x10s  >20.03 (6x10s)    r
```
The photometry was calibrated with nearby stars in UCAC4 catalog. It is consistent with those results reported by Lagioia et al. (GCN 39381), Adami et al. (GCN 39384), Breeveld et al (GCN 39385), Turpin et al. (GCN 39407) and Komesh et al. (GCN 39419).
We thank the observation assistant Guangsheng Zhang and Chunlei Guo 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 #40000
Daniele B. Malesani (DAWN/NBI and Radboud Univ.), Benjamin Schneider (LAM), Gregory Corcoran (UCD), A. Martin-Carrillo (UCD), and Nikko Pyykkinen (NOT and Turku) report on behalf of a larger collaboration:
We observed the field of GRB 250219A (Daigne et al., GCN 39376) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC imager. Observations were carried out with the r-band filter and started on 2025 March 26 at 02:18 UT (34.4 days after the GRB), for a total of 50 min on source. Seeing and Moon conditions were favorable.
Consistent with the position of the optical afterglow (Xin et al., GCN 39380; Magnani et al., GCN 39382; Fu et al., GCN 39383), we detect a faint object with AB magnitude r = 25.2 +- 0.3, calibrated against nearby objects from Pan-STARRS.
While we note a slight offset (~0.9") compared to the afterglow position (Fu et al., GCN 39383), we suggest the above object to be a candidate host galaxy of GRB 250219A.
We thank Liping Xin, Francis Fortin and Susanna Vergani for helpful discussion.

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