GRB250702B

This page lists all entries on GRB250702B in GRBweb

Summary Fermi GBM Fermi GBM Fermi GBM IPN GCN 8864 GCN 40883 GCN 40890 GCN 40904 GCN 40905 GCN 40906 GCN 40908 GCN 40910 GCN 40917 GCN 40924 GCN 40929 GCN 40931 GCN 40949 GCN 40961 GCN 40986 GCN 41014 GCN 41147 GCN 41309 GCN 41767 GCN 42869

Summary table
Variable Value Source
GRB_name_Fermi GRB250702548
T0 13:04:50.126 UTC Fermi_GBM
ra 284.7000° IPN
decl -7.8667° IPN
pos_error 4.00e-02° IPN
T90 63.745 s Fermi_GBM
T90_error 1.846 s Fermi_GBM
T90_start 13:08:06.481 UTC Fermi_GBM
fluence 1.69e-06 erg/cm² Fermi_GBM
fluence_error 5.52e-08 erg/cm² Fermi_GBM
T100 11973.957 s
GBM_located False
mjd 60858.54502460648 Fermi_GBM
Fermi GBM table
GRB_name_Fermi GRB250702682
trigger_name bn250702682
ra 284.6900°
decl -7.8742°
pos_error 6.83e+00°
datum 2025-07-02
t_trigger 16:21:33.072 UTC
T90 422.919 s
T90_error 3.238 s
T90_start 16:17:21.164 UTC
fluence 2.23e-05 erg/cm²
fluence_error 6.60e-08 erg/cm²
flux_1024 2.69e+00 erg/cm²/s
flux_1024_error 2.09e-01 erg/cm²/s
flux_1024_time 1.31e+02 erg/cm²/s
flux_64 5.42e+00 erg/cm²/s
flux_64_error 1.21e+00 erg/cm²/s
Fermi GBM table
GRB_name_Fermi GRB250702581
trigger_name bn250702581
ra 284.6900°
decl -7.8742°
pos_error 5.57e+00°
datum 2025-07-02
t_trigger 13:56:05.766 UTC
T90 230.404 s
T90_error 14.91 s
T90_start 13:55:08.421 UTC
fluence 9.27e-06 erg/cm²
fluence_error 6.23e-08 erg/cm²
flux_1024 2.53e+00 erg/cm²/s
flux_1024_error 2.25e-01 erg/cm²/s
flux_1024_time -2.56e+00 erg/cm²/s
flux_64 6.83e+00 erg/cm²/s
flux_64_error 1.93e+00 erg/cm²/s
Fermi GBM table
GRB_name_Fermi GRB250702548
trigger_name bn250702548
ra 284.6900°
decl -7.8742°
pos_error 9.68e+00°
datum 2025-07-02
t_trigger 13:09:02.034 UTC
T90 63.745 s
T90_error 1.846 s
T90_start 13:08:06.481 UTC
fluence 1.69e-06 erg/cm²
fluence_error 5.52e-08 erg/cm²
flux_1024 1.50e+00 erg/cm²/s
flux_1024_error 1.79e-01 erg/cm²/s
flux_1024_time -3.07e+00 erg/cm²/s
flux_64 4.50e+00 erg/cm²/s
flux_64_error 1.29e+00 erg/cm²/s
IPN table
GRB_name GRB250702B
ra 284.7000°
decl -7.8667°
pos_error 4.00e-02°
GCN 8864 table
GRB_name GRB250702B
GCN_number 8864
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 8864 SUBJECT: GRB 090126A: Swift/UVOT Upper Limits DATE: 09/01/30 18:03:40 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. T. Holland (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC), and M. C. Stroh (PSU) report, on the behalf of the Swift/UVOT team: The Swift/UVOT observed the field of GRB 090126A (Evangelista et al. 2009, GCN Circ. 8852) starting approximately 48 ks after the SuperAGILE detection. We find no new source, relative to the DSS or USNO-B1.0 catalogue, or a variable source, inside the UVOT-enhanced XRT error circle (Stroh et al. 2009, GCN Circ. 8854). Preliminary 3-sigma upper limits for detecting a source in the co-added images, using an aperture-corrected 2.5 arcsecond radius circular aperture, are Filter T_start T_stop Exp(s) Mag ------------------------------------------ v 49,398 55,302 208 >20.1 b 48,033 71,752 3256 >22.7 u 47,960 71,155 333 >21.0 white 48,713 66,162 2022 >23.1 ------------------------------------------ The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight corresponding to a reddening of E_{B-V} = 0.20 mag (Schlegel et al., 1998, ApJS, 500, 525). All photometry is on the UVOT photometry system described in Poole et al. (2008, MNRAS, 383, 627). Please update my e-mail address in your Address Book to . / \ /
GCN 40883 table
GRB_name GRB250702B
GCN_number 40883
Detection_method Fermi GBM final loc
t_trigger 13:56:05 UTC
ra 286.0000°
decl -8.7000°
Circular_text TITLE: GCN CIRCULAR NUMBER: 40883 SUBJECT: GRB 250702B: Fermi GBM Final Real-time Localization DATE: 25/07/02 14:06:41 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 13:56:05 UT on 2 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250702B (trigger 773157370.765606 / 250702581). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 286.0, Dec = -8.7 (J2000 degrees, equivalent to J2000 19h 03m, -8d 41'), with a statistical uncertainty of 7.8 degrees. The angle from the Fermi LAT boresight is 90.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250702581/quicklook/glg_skymap_all_bn250702581.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250702581/quicklook/glg_healpix_all_bn250702581.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250702581/quicklook/glg_lc_medres34_bn250702581.gif
GCN 40890 table
GRB_name GRB250702B
GCN_number 40890
Detection_method Fermi GBM final loc
t_trigger 16:21:33 UTC
ra 286.8000°
decl -17.7000°
Circular_text TITLE: GCN CIRCULAR NUMBER: 40890 SUBJECT: GRB 250702E: Fermi GBM Final Real-time Localization DATE: 25/07/02 16:32:10 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 16:21:33 UT on 2 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250702E (trigger 773166098.071902 / 250702682). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 286.8, Dec = -17.7 (J2000 degrees, equivalent to J2000 19h 07m, -17d 41'), with a statistical uncertainty of 11.6 degrees. The angle from the Fermi LAT boresight is 106.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250702682/quicklook/glg_skymap_all_bn250702682.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250702682/quicklook/glg_healpix_all_bn250702682.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250702682/quicklook/glg_lc_medres34_bn250702682.gif
GCN 40904 table
GRB_name GRB250702B
GCN_number 40904
Detection_method Fermi GBM Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 40904 SUBJECT: Fermi GRB 250702B: Global MASTER-Net observations report DATE: 25/07/03 02:15:23 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 250702B ( Fermi GBM team, GCN 40883) errorbox 36852 sec after notice time and 36888 sec after trigger time at 2025-07-03 00:10:54 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 28 deg. The sun altitude is -68.5 deg. The galactic latitude b = -7 deg., longitude l = 27 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2923151 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 36919 | 2025-07-03 00:10:54 | MASTER-SAAO | (18h 58m 11.78s , -10d 24m 39.1s) | C | 60 | 18.2 | 37016 | 2025-07-03 00:12:31 | MASTER-SAAO | (19h 06m 18.96s , -10d 26m 55.8s) | C | 60 | 18.6 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.
GCN 40905 table
GRB_name GRB250702B
GCN_number 40905
Detection_method Fermi GBM Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 40905 SUBJECT: Fermi GRB 250702E: Global MASTER-Net observations report DATE: 25/07/03 02:15:35 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 250702E ( Fermi GBM team, GCN 40890) errorbox 28126 sec after notice time and 28161 sec after trigger time at 2025-07-03 00:10:54 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 28 deg. The sun altitude is -68.5 deg. The galactic latitude b = -12 deg., longitude l = 19 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2923298 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 28191 | 2025-07-03 00:10:54 | MASTER-SAAO | (18h 58m 11.78s , -10d 24m 39.1s) | C | 60 | 18.2 | 28289 | 2025-07-03 00:12:31 | MASTER-SAAO | (19h 06m 18.96s , -10d 26m 55.8s) | C | 60 | 18.6 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.
GCN 40906 table
GRB_name GRB250702B
GCN_number 40906
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 40906 SUBJECT: EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E DATE: 25/07/03 04:20:00 GMT FROM: EP Team at NAOC/CAS H. Q. Cheng (NAO, CAS), G. Y. Zhao (SYSU), C. Zhou (HUST), Y. H. Cheng (SWIFAR, YNU), Y. J. Zhang (THU), J. W. Hu, H. Sun and Z. X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP250702a. The source was first detected in an observation starting at 2025-07-02T02:53:44 (UTC), and was continuously detected in subsequent observations spanning from 2025-07-02T05:57:06 to 2025-07-02T22:32:44. The WXT position of the source is R.A. = 284.700 deg, DEC = -7.869 deg (J2000) with an uncertainty of 2.4 arcmin in radius (90% C.L. statistical and systematic). The source reached a peak flux in the observation starting at 2025-07-02T16:10:11 with an exposure of 827s, the epoch of which is generally consistent with the burst time of GRB 250702E (GCN 40890). Considering that EP250702a is spatially and temporally coincident with the GRB 250702B,C,D,E detected by Fermi /GBM (GCN 40883, 40885, 40886, 40890, 40891), we suggest that EP250702a is likely the X-ray source associated with GRB 250702B,C,D,E. The WXT position is also consistent with the source localization skymap provided by the Swift/BAT-GUANO (GCN 40903). Stacking of the WXT data taken prior to the WXT detection indicated that the source has already emerged on July 1st, 2025. The WXT spectrum of the peak flux epoch can be fitted with an absorbed power-law model (with the column density fixed at the Galactic absorption value of 5e21 cm^-2), yielding a photon index of 0.2+/-0.1 and an unabsorbed 0.5-4 keV flux of (5.5+/-0.7)e-10 ergs/s/cm^2. A follow-up observation with the Follow-up X-ray Telescope (FXT) onboard EP was performed but the telemetry data is still not available yet. The FXT onboard source detection algorithm gives an improved source position at R.A. = 284.6911 deg, DEC = -7.8715 deg (J2000) with an uncertainty of 20 arcsecond in radius (90% C.L. statistical and systematic). 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)
GCN 40908 table
GRB_name GRB250702B
GCN_number 40908
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 40908 SUBJECT: EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits DATE: 25/07/03 07:38:27 GMT FROM: Amit Kumar at Royal Holloway - UoL/ U of Warwick, UK A. Kumar, B. P. Gompertz, G. Ramsay, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, D. O'Neill, B. Godson, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, and J. Casares report on behalf of the GOTO collaboration: We report on observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to GRB 250702B, C, D and E (Fermi GBM Team, GCNs 40883, 40885, 40886, 40890 and 40891). Targeted observations were performed between 2025-07-02 23:16:56 UT and 2025-07-03 02:52:31 UT (between 20.39 and 23.98 hours after trigger). Each observation 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. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogues. Human vetting was carried out in real time on any candidates that passed the above checks. We identify no candidate optical counterparts within the EP/FXT (Cheng et al. 40906) 90% localisation region with typical 3-sigma limits ranging between L > 19.85 to L > 20.35 (AB). The deepest of these was taken at a mid-time of 2025-07-03 02:06:10 UT (23.21 hours after trigger). Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction. (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 40910 table
GRB_name GRB250702B
GCN_number 40910
Detection_method MAXI Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 40910 SUBJECT: MAXI/GSC detection of an X-ray activity from a transient associated with GRB 250702B,C,D,E and EP250702a DATE: 25/07/03 09:47:38 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University Y. Kawakubo, M. Serino (AGU), H. Negoro, M. Nakajima, , K. Takagi, H. Takahashi, K. Tatano, H. Nishio (Nihon U.), T. Mihara, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), T. Sakamoto, S. Sugita, H. Hiramatsu, Y. Kondo, A. Yoshida (AGU), Y. Tsuboi, H. Sugai, N. Nagashima (Chuo U.), M. Shidatsu, Y. Niida, C. Kang, T. Nakamoto (Ehime U.), I. Takahashi, Y. Yatsu (Science Tokyo), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, M. Kurihara (JAXA), Y. Ueda, K. Fujiwara (Kyoto U.), M. Yamauchi, M. Nishio, C. Hiraizumi (Miyazaki U.), K. Yamaoka (Nagoya U.), M. Sugizaki (Kanazawa U.), W. Iwakiri (Chiba U.), T. Kawamuro (Osaka U.), S. Yamada (Tohoku U) We report on the MAXI/GSC detection of an X-ray transient source on July 2, 2025 (MJD 60858) associated with GRB 250702B,C,D,E/EP250702a. The source was clearly detected at three scan transits from 2025-07-02T12:59 UT to 2025-07-02T16:15. Assuming that the source flux was constant over the three transits, we obtain the source position at (284.462 deg, -7.936 deg) = (18 57 50, -07 56 09) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.34 deg and 0.24 deg, respectively. The roll angle of the long axis from the north direction is 54.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the three scans was 54 +- 11 mCrab. The time and the source position determined by the MAXI observations are consistent with GRB 250702B, C, D, E, observed by Fermi-GBM (GCN 40883, 40885, 40886, 40890, 40891), the source localization skymap provided by Swift/BAT-GUANO (GCN 40903) and EP250702a observed by the Einstein Probe/WXT, FXT (GCN 40906). Follow-up observations are encouraged.
GCN 40917 table
GRB_name GRB250702B
GCN_number 40917
Detection_method Konus-Wind Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 40917 SUBJECT: EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation DATE: 25/07/03 15:05:29 GMT FROM: EP Team at NAOC/CAS H. Q. Cheng (NAO, CAS), Y. J. Zhang (THU), G. Y. Zhao (SYSU), C. Zhou (HUST), Y. H. Cheng (SWIFAR, YNU), Y. L. Wang (NAO, CAS; ICE, CSIC-IEEC), F. Coti Zelati, A. Marino, N. Rea (ICE, CSIC-IEEC), J. W. Hu, H. Sun, Z. X. Ling, W. Yuan (NAO, CAS) on behalf of the Einstein Probe (EP) team: Following the detection of GRB 250702B, C, D, E by Fermi/GBM (GCN 40883, 40885, 40886, 40890, 40891) and its likely X-ray counterpart EP250702a detected by Einstein Probe (EP, GCN 40906, ATel #17261), MAXI (GCN 40910) and Konus-Wind (GCN 40914), we performed a follow-up observation on EP250702a with the Follow-up X-ray Telescope (FXT) onboard EP. The observation began at 2025-07-03T02:44:11, with an exposure of about 3875 s. Our on-ground analysis showed that an X-ray source is detected at R.A.= 284.6895 deg, Dec= -7.8738 deg, with an uncertainty of 10 arcsecond (90% C.L. systematic and statistical), which is within the error circle of the EP-WXT position of EP250702a. Considering the possibility of the source being a Galactic object and given the improved source localization, we also designate the source EP J185845.5-075225. The FXT spectrum can be fitted with an absorped power law model, yielding a column density of (7.9+/-0.6)e21 cm^-2, a photon index of 1.57+/-0.07, and an unabsorbed 0.5-10 keV flux of (5.52+/-0.21)e-11 erg/s/cm^2. We also performed preliminary timing analysis using the FXT data collected so far, and no significant periodic or quasi-periodic signals were detected. EP-FXT will continue to monitor this source in the next days. The contact transient advocates of this source are Huaqing Cheng (hqcheng@nao.cas.cn) and Yi-Jia Zhang (zhangyij21@mails.tsinghua.edu.cn). Please contact them for coordination of multi-wavelength follow-up observations. 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 40924 table
GRB_name GRB250702B
GCN_number 40924
Detection_method Swift-XRT Other
ra 284.6899°
decl -7.8739°
Circular_text TITLE: GCN CIRCULAR NUMBER: 40924 SUBJECT: GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate DATE: 25/07/03 18:17:16 GMT FROM: Antonio Martin-Carrillo at UCD,Space Science Group A. Martin-Carrillo (UCD), A. J. Levan (Radboud), B. Schneider (LAM), J. An (NAOC), D. Xu (NAOC), S. Campana (INAF-OAB), G. Corcoran (UCD), P. G. Jonker (Radboud), D. B. Malesani (DAWN/NBI and Radboud) report on behalf of the Stargate collaboration: We observed the location of EP250702a (Cheng et al., GCNs 40906, 40917) likely associated with GRB 250702B,C,D,E detected by Fermi/GBM (Fermi GBM Team, GCNs 40883, 40885, 40886, 40890), Swift/BAT (via de GUANO system; DeLaunay et al., GCN 40903) and Konus/Wind (Frederiks et al., GCN 40914), all likely originating from the same astrophysical source (Neights et al., GCN 40891). We used the ESO VLT UT4 (Yepun) equipped with the HAWK-I near-infrared camera. We obtained two 20 min exposures in each of the H and K bands, starting on 2025 July 3 at 07:03:03 UT (17.1 hr after the first Fermi trigger, GRB 250702B). At the location of the UVOT-enhanced (2" radius) coordinates provided by Swift/XRT (Kennea et al., GCN 40919) we identify a bright source not visible in archival H and K images from VISTA/VHS and UKIDSS at the following coordinates (J2000): RA (J2000) = 18:58:45.57 Dec (J2000) = -07:52:26.2 with an uncertainty of ~0.5" in each axis. The source has a magnitude of K ~ 17.3 (Vega), calibrated against 2MASS stars. We note that, while the source is dominated by point-like emission, it appears to be extended along the E-W direction. As this is a crowded field, this could be just the result of source confusion. Alternatively, if the extension is real, it could be related to nebulosity around a Galactic source, or be a distant host galaxy which would imply an extragalactic origin for GRBs 250702B,C,D,E / EP250702a. Further observations are planned and encouraged to reveal the nature of this unusual gamma-ray burster. We acknowledge excellent support from the observing staff in Paranal, in particular Marco Berton, Robert Klement, Susana Cerda-Hernandez, Thomas Rivinius, and Thomas Szeifert.
GCN 40929 table
GRB_name GRB250702B
GCN_number 40929
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 40929 SUBJECT: GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit DATE: 25/07/04 02:24:14 GMT FROM: I. Perez-Garcia at Institute of Astrophysics of Andalusia I. Pérez-García, A. J. Castro-Tirado, M. D. Caballero-García, S. Guziy, R. Sánchez-Ramírez, S.-Y. Wu (IAA-CSIC Granada), G. García-Segura (Instituto de Astronomía de la UNAM, Ensenada), M. Gritsevich (Univ. of Helsinki), Y.-D. Hu (Guanxi Univ.), S. Góngora-García and J.-F.Agüí-Fernández (CAHA), on behalf of a larger collaboration, report: We observed the location of EP250702a (Cheng et al., GCN 40906, 40917), associated with the four high-energy events GRB 250702B,C,D,E, all detected by Fermi/GBM (Fermi GBM Team, GCN 40883, 40885, 40886, 40890), Swift/BAT (GUANO system; DeLaunay et al., GCN 40903) and Konus/Wind (Frederiks et al., GCN 40914), with all these events likely originating from the same astrophysical source (Neights et al., GCN 40891). Using the 2.2m CAHA telescope in Spain (equipped with CAFOS), we obtained 60s exposures in the z-band, starting on 2025 July 3 at 23.99 UT (i.e. 34.1 hr after the first Fermi trigger, GRB 250702B). At the location of the UVOT-enhanced position provided by Swift/XRT (Kennea et al., GCN 40919) and the VLT nIR source reported by Martin-Carrillo et al. (GCN 40924), we do not detect an optical source on the co-added z-band (1980s total exposure time) down to z = 21.4 (3-sigma limiting magnitude), using the Pan-STARRS1 DR2 (Magnier et al. 2025) catalogue as reference. We thank the staff at CAHA for their excellent support.
GCN 40931 table
GRB_name GRB250702B
GCN_number 40931
Detection_method Fermi GBM Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 40931 SUBJECT: Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst DATE: 25/07/04 03:47:31 GMT FROM: eliza.neights@gmail.com E. Neights (GWU, NASA GSFC), O.J. Roberts (USRA, NASA MSFC), E. Burns (LSU), P. Veres (UAH), E. Bissaldi (Politecnico and INFN Bari) report on behalf of the Fermi-GBM Team: On July 2, 2025, Fermi-GBM triggered four times on gamma-ray emission emanating from a similar localization of the sky (GCNs 40883, 40885, 40886, 40890, 40891), over an interval of 11.5 ks, believed likely to be from the same source. Konus-Wind observations (GCN 40914) provide further support that these triggers may be related to a similar origin, but with a combined duration of >15 ks. A combined GBM skymap was found to be spatially consistent with Swift-BAT GUANO detections of 250702D, C and E (GCN 40903). Emission from 250702E was found to be spatially and temporally coincident with Einstein Probe Transient, EP250702a (GCN 40906, 40917). While it is currently named with the phenomenological GRB convention, the physical origin is still uncertain. Upon further investigation, the pulse which caused the GBM trigger labeled 250702C was from an unrelated short GRB. That is, emission from the short burst and the ultra-long 250702B are contemporaneous, but arise from inconsistent locations. In light of this, spectral analysis was conducted for the three triggers of GRB 250702B, matched to their previous designations below. We observe photons in the BGO up to 1 MeV, with the majority of the photons occurring in the 50-300 keV range. The spectral analyses of these events are summarized below, which are fit about equally well with power law and Band function models: GRB Name | Trigger Time/T0 (UT) | Interval (s) | Power Law Index | Fluence (erg/cm2) 250702E | 16:21:33.07 | T0-6.1 - T0+147.5 | -1.38 +/- 0.01 | (2.74 +/- 0.05)E-05 250702B | 13:56:05.77 | T0-30.7 - T0+26.6 | -1.34 +/- 0.01 | (1.24 +/- 0.03)E-05 250702D | 13:09:02.03 | T0-95.2 - T0+12.3 | -1.29 +/- 0.02 | (1.04 +/- 0.05)E-05 GRB Name | Trigger Time/T0 (UT) | Interval (s) | Band Alpha | Band Beta | Band Peak Energy (keV) | Fluence (erg/cm2) 250702E | 16:21:33.07 | T0-6.1 - T0+147.5 | -0.81 +/- 0.05 | -5.1 +/- 22.7 | 610 +/- 60 | (3.4 +/- 0.1)E-05 250702B | 13:56:05.77 | T0-30.7 - T0+26.6 | -0.8 +/- 0.1 | -1.52 +/- 0.04 | 400 +/- 200 | (1.38 +/- 0.05)E-05 250702D | 13:09:02.03 | T0-95.2 - T0+12.3 | -0.2 +/- 0.3 | -1.7 +/- 0.1 | 400 +/- 100 | (1.48 +/- 0.09)E-05
GCN 40949 table
GRB_name GRB250702B
GCN_number 40949
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 40949 SUBJECT: GRB 250702B / EP2050702a: FTW optical and NIR observations DATE: 25/07/04 13:59:08 GMT FROM: Malte Busmann at Ludwig-Maximilians-Universität München Malte Busmann (LMU), Xander J. Hall (Carnegie Mellon U.), Brendan O’Connor (Carnegie Mellon U.), Daniel Gruen (LMU), Julian Sommer (LMU), and Antonella Palmese (Carnegie Mellon U.) report: We observed the location of GRB 250702B / EP250702a (Fermi GBM Team, GCNs 40883, 40886, 40890; Neights et al., GCNs 40891, 40931; DeLaunay et al., GCN 40903; Cheng et al., GCNs 40906, 40917; Kawakubo et al, GCN 40910; Frederiks et al., GCN 40914; Wang et al., GCN GCN 40923) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i and J band simultaneously for 40 x 180 s starting at 2025-07-03T21:52:47 UT. We do not detect the source seen by Martin-Carrillo et al. (GCN 40924) or any other new source in the Swift/XRT localization (Kennea at al., GCN 40919) to 3 sigma limiting magnitudes of r > 23.6 AB mag i > 22.7 AB mag J > 21.7 AB mag. Compared to the K-band magnitude reported by Martin-Carrilo et al. (GCN 40924) this implies an extremely red color of the source, which implies a dusty environment, as also supported by the hydrogen column density inferred from the Swift/XRT observations (Kennea at al., GCN 40919). This is consistent with previous observations by Lipunov et al. (GCNs 40904, 40905, 40912), Kumar et al. (GCN 40908), Becerra et al. (GCN 40918), and Pérez-García et al. (GCN 40929). The r and i band magnitudes are calibrated against the PS1 catalog and the J band is calibrated with the 2MASS Catalog. The magnitudes are not corrected for Galactic extinction. We thank Silona Wilke from the Wendelstein Observatory staff for obtaining these observations.
GCN 40961 table
GRB_name GRB250702B
GCN_number 40961
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 40961 SUBJECT: GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart DATE: 25/07/04 21:57:00 GMT FROM: Andrew Levan at Radboud University A. J. Levan (Radboud & Warwick), A. Martin-Carrillo (UCD), B. Schneider (LAM), P. G. Jonker (Radboud), D. B. Malesani (DAWN/NBI and Radboud), B. P. Gompertz (Birmingham), G. Corcoran (UCD), M. De Pasquale (Univ. Messina) report on behalf of the Stargate collaboration: We performed a second observation of the near-infrared source reported by Martin-Carrillo et al. (GCN 40924) likely associated with EP250702a (Cheng et al., GCNs 40906, 40917) and GRB 250702B,D,E detected by Fermi/GBM (Fermi GBM Team, GCNs 40883, 40886, 40890), Swift/BAT (via the GUANO system; DeLaunay et al., GCN 40903) and Konus/Wind (Frederiks et al., GCN 40914). We used the ESO VLT UT4 (Yepun) equipped with the HAWK-I near-infrared camera. We obtained 10-min exposures in each of the H and K bands, starting on 2025 July 4 at 03:16:28 UT (1.56 days after the first Fermi trigger, GRB 250702B). Compared to our previous measurement (Martin-Carrillo et al., GCN 40924), the counterpart has faded by ~1.3 mag in the K band (and a consistent amount in H). Assuming a power-law decay, this gives a decay index ~1.7 (relative to the first Fermi trigger time). The source is also extremely red, with an approximate colour of H-K ~ 2.5 (Vega). This is far from what is typically observed in transients and is not straightforward to explain even through dust extinction. The red color also easily explains the lack of optical detections (Siegel, GCN 40952; Busmann et al., GCN 40949; Hua et al., GCN 40943; Pérez-García et al., GCN 40929; Becerra et al., GCN 40918; Kumar et al., GCN 40908). Our second epoch clearly reveals an extended source under the location of the near-infrared source. The true nature of this extended source is still not confirmed, although it appears morphologically to be a disc-like galaxy. On this assumption, based on the offset and approximate magnitude, we infer a chance probability of ~0.05%. If this is correct, it would suggest an extragalactic origin for GRBs 250702B,D,E / EP250702a. We acknowledge excellent support from the observing staff in Paranal, in particular Susana Cerda-Hernandez, Thomas Szeifert, Marco Berton and Robert Klement
GCN 40986 table
GRB_name GRB250702B
GCN_number 40986
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 40986 SUBJECT: GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope DATE: 25/07/06 04:15:00 GMT FROM: lixia76@mail2.sysu.edu.cn Xia Li, Chun Chen, Zhong-nan Dong, Duo-le Cao, Wei-Sen Huang, Jin-Ji Li, Jia-Qi Lin, Pu Lin, Yan Yu, Hao-Nan Yang, Hao-Ran Zhang, Xiang-Tao Zeng, P H Thomas Tam, Rong-Feng Shen, Bin Ma (Sun Yat-sen University) report on behalf of the SYSU 80cm infrared telescope team: We observed the field of GRBs 250702B,C,D,E / EP250702a (H. Q. Cheng et al., GCN 40906; Y. Kawakubo et al., GCN 40910; D. Frederiks et al., GCN 40914; H. Q. Cheng et al., GCN 40917; J. A. Kennea et al., GCN 40919; Chen-Wei Wang et al., GCN 40923; E. Neights et al., GCN 40931) using the Sun Yat-sen University 80cm infrared telescope with 58 x 20 s exposures in J band. The calculated position is RA. = 18:58:45.61, DEC =-07:52:26.9 J2000, from Swift/XRT observation (J. A. Kennea et al., GCN 40919). Our observations began at 2025-7-3 19:36:00 UTC (29.67 hours after the first Fermi trigger, GRB 250702B). We do not detect any optical counterpart (A. Kumar et al., GCN 40908; V.Lipunov et al., GCN 40912; Rosa L. Becerra et al., GCN 40918; I. Pérez-García et al., GCN 40929; Yan-Long Hua et al., GCN 40943; Malte Busmann et al., GCN 40949; M. H. Siegel, GCN 40952) at the position of the near-infrared afterglow (A. Martin-Carrillo et al., GCN 40924; A. J. Levan et al., GCN 40961), down to a 5-sigma depth of J~ 17.5 Vega magnitudes. The SYSU 80cm infrared telescope is operated and managed by the Department of Astronomy, Sun Yat-sen University.
GCN 41014 table
GRB_name GRB250702B
GCN_number 41014
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 41014 SUBJECT: EP250702a/ GRB 250702B: NuSTAR X-ray Observations DATE: 25/07/07 17:46:46 GMT FROM: Brendan O'Connor at Carnegie Mellon University Brendan O’Connor (CMU), Dheeraj Pasham (Eureka Scientific/George Washington), Igor Andreoni (UNC), Jeremy Hare (Catholic/GSFC) report on behalf of a larger collaboration: We observed the X-ray transient EP250702a (GCN 40906), which is also associated with the multiple gamma-ray triggers designated as GRB 250702B/D/E (GCNs 40883, 40886, 40890, 40891, 40931, 40903, 40914, 40923), with the NuSTAR X-ray Telescope through a Target of Opportunity observation through GO program 11282 (PI: Pasham). The observation occurred between 2025-07-03 20:45:21 and 2025-07-04 09:15:00 UTC for an on-source exposure of ~21.5 ks, simultaneous with Swift/XRT observations (ObsID: 19906002). The source is clearly detected at an average rate of ~0.4 cts/s. The 3-79 keV X-ray lightcurve shows short term variability throughout the full exposure in both FPMA and FPMB, but no flaring is observed. The source varies in count rate by a factor of 2-3 on timescales as short as a few ks. Compared to NuSTAR observations of GRB 221009A at a similar count rate (GCNs 32695, 32788), the source shows more significant variability, which we suggest disfavors an ultralong GRB origin, especially in conjunction with the July 1st onset reported by the Einstein Probe (GCN 40906). The X-ray spectra are featureless and do not show any Fe lines or reflection features. This is consistent with the lack of features in the Swift/XRT spectra. The 3-79 keV spectrum (FPMA+FPMB) is well fit by an absorbed powerlaw with a photon index of Gamma~1.81+/-0.03, which is consistent with the initial Swift/XRT spectral index within errors (GCN 40919). The hydrogen column density was fixed to 1e22 cm^-2 as per the best-fit Swift/XRT spectra (see https://www.swift.ac.uk/LSXPS/transients/9377). The unabsorbed 3-79 keV flux (time-averaged) is (2.35+/-0.05)e-11 erg/cm^2/s during our observation. We also performed a fit with an absorbed cutoff powerlaw and find a cutoff energy >60 keV. In this case, the best-fit photon index is Gamma~1.67+/-0.08. This has better agreement with the EP/FXT result, although the FXT observation was obtained at an earlier time (GCN 40917). The C-stat between both fits to the NuSTAR data was nearly identical and the cutoff powerlaw is not a statistically significant improvement. We suggest that the lack of Fe lines, and lack of cutoff in the powerlaw spectra (out to at least 60 keV), is atypical for an X-ray binary. We performed a Lomb-Scargle analysis on the barycenter corrected X-ray data, and did not identify any periodic signals over the frequency range 1e-3 to 100 Hz, consistent with the EP/FXT report (GCN 40917). The periodogram becomes red noise dominated below 3e-3 Hz. Further analysis is underway and additional NuSTAR and Swift observations are planned. We thank the NuSTAR SOC, and in particular Karl Forster and Brian Grefenstette, for promptly implementing these observations.
GCN 41147 table
GRB_name GRB250702B
GCN_number 41147
Detection_method Other
ra 284.6898°
decl -7.8740°
Circular_text TITLE: GCN CIRCULAR NUMBER: 41147 SUBJECT: EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz DATE: 25/07/24 17:27:21 GMT FROM: stephane.corbel@cea.fr Author: N. Grollimund, S. Corbel (Univ. Paris Cité & CEA Saclay), A. Coleiro, F. Cangemi (Univ. Paris Cité), J. Rodriguez (CEA Saclay) on behalf of a larger team. We observed the field of EP250702a (GCN 40906) with the MeerKAT radio telescope (proposal ID MKT-24172; PI: Corbel) using the S-band receivers, at a central frequency of 3.06 GHz. We conducted our observations from 2025-07-21 23:34:37 UTC, with a total on-source time of 11 min. We used J1939-6342 for flux and bandpass calibration, and J1822-0938 for complex gain calibration. We detect a point source with a flux density of 147 +/- 19 uJy at the position of EP250702a, with an RMS noise level of ~15 uJy/beam. Our observation, in combination with the detection of a ~100 uJy point source reported in GCN 40985, implies that the flux of EP250702a increased by ~50% at 3 GHz between 2025-07-04 and 2025-07-21. Averaging the fitted positions from all of our S-band observations, we find a refined radio position for the source: R.A. = 18:58:45.549 +/- 0.01s, Dec. = -7:52:26.54 +/- 0.15’'. This position is consistent with the radio position reported by VLA in GCN 41053, as well as the NIR and X-ray counterparts (GCNs 40924, 40906). Further observations are planned. We thank the SARAO staff for rapidly scheduling these observations. The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. This work has made use of the "MPIfR S-band receiver system" designed, constructed and maintained by funding of the MPI für Radioastronomie and the Max-Planck-Society.
GCN 41309 table
GRB_name GRB250702B
GCN_number 41309
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 41309 SUBJECT: GRB 250702B: Chandra X-ray Detection DATE: 25/08/09 23:30:50 GMT FROM: Brendan O'Connor at Carnegie Mellon University B. O’Connor (CMU), D. Pasham (Eureka/George Washington), I. Andreoni (UNC), J. Hare (Catholic/GSFC), X. Hall (CMU), J. Carney (UNC), A. Palmese (CMU), M. Busmann (LMU), D. Gruen (LMU), report on behalf of a larger collaboration: We observed the position of the ultra-long X-ray and gamma-ray transient GRB 250702B (GCN #40883, #40886, #40890), also known as EP250702a (GCN #40906), with the Chandra X-ray Observatory (CXO) through Director's Discretionary Time (PI: O'Connor). Observations were carried out with ACIS-S starting on 2025-08-09 at 05:49:28 UT, corresponding to ~38 d after the initial Fermi trigger, for a total of 27.7 ks. We detect a clear X-ray source at the position of the infrared and radio counterparts of GRB 250702B (GCNs #40924, #41053). Adopting the best-fit spectrum from Swift/XRT (GCN #40919), we derive an unabsorbed 0.3-10 keV flux of ~3.3e-14 erg/cm^2/s. This is consistent with the extrapolation of the decay observed by Swift/XRT at earlier times (<10 days), and favors a powerlaw with temporal slope ~-1.9 as measured from the initial Fermi trigger time (GRB 250702D; GCN #40886). Further analysis is underway. We thank Pat Slane for approving our DDT request, and the entire staff of the Chandra X-ray Observatory for scheduling the observations.
GCN 41767 table
GRB_name GRB250702B
GCN_number 41767
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 41767 SUBJECT: GRB 250702B: Late time Chandra observations DATE: 25/09/09 20:42:37 GMT FROM: Rob Eyles-Ferris at U of Leicester R. A. J. Eyles-Ferris (U of Leicester), A. J. Levan (Radboud and Warwick), A. Martin-Carrillo (UCD), P. T. O’Brien (U of Leicester), M. De Pasquale (Univ. Messina), B. P. Gompertz (U. Birmingham), T. Laskar (Utah), D. B. Malesani (DAWN/NBI and Radboud), J. C. Rastinejad (Maryland), S. Schulze (Northwestern), N. R. Tanvir (U of Leicester), P. G. Jonker (Radboud) and D. Watson (DAWN/NBI) report on behalf of a larger collaboration: We observed the position of the gamma-ray and X-ray transient GRB 250702B/EP250702a (Fermi GBM Team, GCNs 40883, 40886, 40890; Cheng et al., GCN 40906) with the Chandra X-ray Observatory through a Director’s Discretionary Time request (PI: Eyles-Ferris) using ACIS-S. Our observation started at 2025-09-05 23:26:41 UT, approximately 65 days after the initial Fermi trigger, and lasted 39.55 ks. At the position of GRB 250702B, we detect the X-ray counterpart (Cheng et al., GCN 40906; Kennea et al., GCN 40919; O’Connor et al., GCN 41309) with a preliminary count rate of ~3.1e-4 ct/s. Assuming the same spectrum as derived from Swift/XRT observations, this corresponds to a flux ~6.7e-15 erg/cm^2/s. This is broadly consistent with the alpha ~ 1.9 decay slope measured in both the Swift/XRT light curve and previous Chandra observations (O’Connor et al., GCN 41309). Further analysis of these data is ongoing. We thank Pat Slane and the Chandra X-ray Center team for approving and scheduling our DDT request.
GCN 42869 table
GRB_name GRB250702B
GCN_number 42869
Detection_method Other
ra 284.6899°
decl -7.8740°
Circular_text TITLE: GCN CIRCULAR NUMBER: 42869 SUBJECT: GRB 250702B: detection of the compact radio counterpart 139 days after the burst DATE: 25/11/28 12:16:56 GMT FROM: ailing.wang.wal@gmail.com Ailing Wang (IHEP), Tao An, Yuanqi Liu (SHAO), Jinjun Geng, Songbo Zhang, Xuefeng Wu (PMO), Xinwen Shu (ANU) et al. report: We are conducting a multi-telescope, multi-epoch, multi-frequency radio campaign on GRB 250702BCD to trace its long-term afterglow evolution. Previous radio observations from other facilities have been reported by independent groups (e.g. GCNs 40983, 40985, 41053, 41059, 41061). Here we report results from Karl G. Jansky Very Large Array (VLA) observations on 2025 November 18 in B-array configuration. The data were calibrated and imaged with standard procedures in CASA. At C band (the central frequency of 6 GHz), we detect a radio source at the position of the known counterpart to GRB 250702B. The source is unresolved with a synthesized beam of 1.42 arcsec × 2.40 arcsec (PA = 28 deg) and has a peak flux density of ≈ 200 μJy beam⁻¹. The measured peak position is RA (J2000) = 18:58:45.5648 Dec (J2000) = -07:52:26.235 which is consistent with previously reported radio positions of the counterpart (GCN 41053). Complementary observations with eMERLIN and the European VLBI Network (EVN) yield flux densities consistent with the VLA measurement. This agreement indicates that the bulk of the radio emission, arising from long-lived synchrotron radiation (Levan et al. 2025, O'Connor et al. 2025), remains confined to a compact component on milliarcsecond to sub-arcsecond scales. This late-time detection at approximately 139 days after the 2025 July 2 trigger provides an important additional point on the radio light curve and confirms the persistence of a compact radio source. The full multi-epoch, multi-resolution dataset will be used to characterize the long-lived synchrotron emission and continued long-term monitoring is scheduled. We thank the TACs and operations staff of the VLA, eMERLIN, EVN, and ATCA for approving and supporting these observations.