May 2025 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 38570] GRB 250523A: Fermi GBM Final Real-time Localization
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40538 SUBJECT: GRB 250523A: Fermi GBM Final Real-time Localization DATE: 25/05/23 14:36:55 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 14:26:23 UT on 23 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250523A (trigger 769703188.305002 / 250523602). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 52.9, Dec = 55.2 (J2000 degrees, equivalent to J2000 03h 31m, 55d 12'), with a statistical uncertainty of 3.0 degrees. The angle from the Fermi LAT boresight is 38.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250523602/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250523602/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250523602/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40538. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38569] The EP-WXT trigger 01709176712 is likely a flaring star
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40537 SUBJECT: The EP-WXT trigger 01709176712 is likely a flaring star DATE: 25/05/23 13:45:17 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> J.Yang (NJU), R.-Z. Li (YNAO, CAS), Q.-C. Shui (IHEP, CAS), H.-Q. Cheng and C.-C. Jin (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709176712 at the time of 2025-05-23T12:44:31, is likely a stellar flare associated with Gaia DR3 6277472183485764992 (R.A., DEC. = 213.94224, -21.58397 deg.). The estimated flux of the flare is around 8e-11 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 2.5e+33 erg/s. 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). View this GCN Circular online at https://gcn.nasa.gov/circulars/40537. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38568] GRB 250521B: SVOM/VT optical upper limit
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40536 SUBJECT: GRB 250521B: SVOM/VT optical upper limit DATE: 25/05/23 12:43:46 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, Y. L. Qiu, L. P. Xin, C. Wu, Z. H. Yao, 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), A. Foisseau (APC) and C. Lachaud (APC) report on behalf of the SVOM/VT team. SVOM/VT conducted ToO follow-up observations of the GRB 250521B (Foisseau et al., GCN 40513). The observation started on 2025-05-21T20:11:45 UT (i.e. 15.87 hour after trigger time) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously. No uncatalogued source was detected, compared to the Legacy survey, within errorboxes of the candidates reported by Swift-XRT (Evans et al., GCN 40517) and EP-FXT (Shui et al., GCN 40532), down to 3 sigma upper limit of VT_R~24.0 mag (AB) in 109*100 sec stacked images at the mid time of 19.29 hour. The upper limit is consistent with the report by Angulo et al. (GCN 40521). 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/40536. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38567] The EP-WXT trigger 01709176612: SVOM/VT optical observations
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40535 SUBJECT: The EP-WXT trigger 01709176612: SVOM/VT optical observations DATE: 25/05/23 12:16:31 GMT FROM: Liping Xin at NAOC, SVOM <xlp(a)nao.cas.cn> L. P. Xin, Y. L. Qiu, H. L. Li, C. Wu, Z. H. Yao, Y. N. Ma, X. H. Han, J. Wang, H. Q. Cheng (NAO, CAS), Q. C. Shui (IHEP, CAS), Y. J. Song, Z. X. Ling (NAO, CAS) report on behalf of the SVOM and EP mission teams: SVOM performed a Target of Opportunity observation of he EP-WXT trigger 01709176612 (Song et al., GCN 40523, Chen et al.,, GCN 40534). SVOM/VT began observing the field at 2025-05-22T06:57:11 UTC, 60.32 min after the trigger in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. The exposure time for each frame is 70 seconds. The WISEA J122501.45-521614.6 identified as the counterpart of the trigger (Evans et al., GCN 40528, Chen et al., GCN 40534) was saturated in all VT_R band images, but showed a fading for roughly 0.5 mag from saturated to about 13.3 mag (AB) in VT_B band during our 2 orbit observations. The optical variation in VT_B is consistent with the stellar flare (Chen et al., GCN 40534). 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/40535. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38566] The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40534 SUBJECT: The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation DATE: 25/05/23 10:06:35 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> H. Q. Cheng (NAO, CAS), Q. C. Shui (IHEP, CAS), Y. J. Song, Z. X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team: The on-ground analysis of EP-FXT observations shows that the EP-WXT trigger (ID: 01709176612) should be originated from a stellar flare associated with WISEA J122501.45-521614.6, but not Gaia DR3 6077506855610363648. A better localization from the refined analysis is derived as R.A. = 186.2573 deg, Dec = -52.2713 deg (J2000), with an error radius of 10 arcsec (90% C.L.). This is spatially coincident with WISEA J122501.45-521614.6, with a separation of 3.4 arcsec. The result is consistent with the candidate counterpart identified in Swift/XRT observations (Evans et al., GCN #40528). Based on this positional agreement, we suggest that the EP-WXT trigger originates from WISEA J122501.45-521614.6. The previously suggested Young Stellar Object (YSO) candidate, Gaia DR3 6077506855610363648 (Song et al. GCN #40523), has been excluded as the counterpart due to its larger offset of 14.1 arcsec from the FXT error circle. View this GCN Circular online at https://gcn.nasa.gov/circulars/40534. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38565] Fermi GRB 250522B: Global MASTER-Net observations report
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40533 SUBJECT: Fermi GRB 250522B: Global MASTER-Net observations report DATE: 25/05/23 07:31:07 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 250522B ( Fermi GBM team, GCN 40531) errorbox 27574 sec after notice time and 49860 sec after trigger time at 2025-05-23 06:59:53 UT, with upper limit up to 20.3 mag. The observations began at zenith distance = 29 deg. The sun altitude is -55.1 deg. The galactic latitude b = -24 deg., longitude l = 343 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2878662 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 49910 | 2025-05-23 06:59:53 | MASTER-OAFA | (19h 44m 22.76s , -56d 37m 08.7s) | C | 100 | 18.9 | 49920 | 2025-05-23 06:59:53 | MASTER-OAFA | (20h 00m 53.97s , -56d 11m 31.1s) | C | 120 | 20.2 | 50055 | 2025-05-23 07:02:17 | MASTER-OAFA | (19h 44m 22.46s , -56d 38m 27.6s) | C | 100 | 18.9 | 50065 | 2025-05-23 07:02:17 | MASTER-OAFA | (20h 00m 54.27s , -56d 12m 49.5s) | C | 120 | 20.2 | 50193 | 2025-05-23 07:04:35 | MASTER-OAFA | (19h 44m 26.76s , -56d 36m 55.4s) | C | 100 | 19.1 | 50203 | 2025-05-23 07:04:35 | MASTER-OAFA | (20h 00m 57.96s , -56d 11m 17.4s) | C | 120 | 20.3 | 50328 | 2025-05-23 07:06:51 | MASTER-OAFA | (19h 44m 20.88s , -56d 37m 43.4s) | C | 100 | 19.0 | 50339 | 2025-05-23 07:06:51 | MASTER-OAFA | (20h 00m 52.54s , -56d 12m 05.3s) | C | 120 | 20.2 | 50465 | 2025-05-23 07:09:07 | MASTER-OAFA | (19h 44m 22.05s , -56d 36m 37.8s) | C | 100 | 18.9 | 50475 | 2025-05-23 07:09:07 | MASTER-OAFA | (20h 00m 53.32s , -56d 11m 00.0s) | C | 120 | 20.2 | 50601 | 2025-05-23 07:11:23 | MASTER-OAFA | (19h 44m 26.58s , -56d 37m 34.2s) | C | 100 | 18.9 | 50611 | 2025-05-23 07:11:23 | MASTER-OAFA | (20h 00m 58.26s , -56d 11m 55.7s) | C | 120 | 20.2 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40533. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38564] GRB 250521B: EP-FXT follow-up observation and afterglow candidates
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40532 SUBJECT: GRB 250521B: EP-FXT follow-up observation and afterglow candidates DATE: 25/05/23 07:17:35 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Q. C. Shui (IHEP, CAS), H. Q. Cheng, Y. J. Song, Z. X. Ling (NAO, CAS), A. Foisseau, C. Lachaud (APC), M. Brunet (IRAP), N. Dagoneau (CEA) report on behalf of the Einstein Probe and SVOM team We performed a follow-up observation of GRB 250521B (detected through offline search of SVOM/ECLAIRs, Foisseau et al, GCN #40513; followed by Swift/XRT, Evans et al. GCN #40517 and SVOM/COLIBRI, Angulo et al. GCN #40521), with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation began at 2025-05-22T02:46:16 (T-TGRB ~ 22.5 hrs), and the exposure time is about 5.2 ks. 3 uncatalogued sources were detected both by FXTA and FXTB in the 90% localization error circle provided by SVOM/ECLAIRs (with a radius of 12.2 arcmin centered at RA, DEC = 200.822 deg, +1.766 deg), as listed below (the FXT flux is taken from FXTB module). Source name | RA | DEC | Estimated Flux | SNR | Dist from SVOM/ECLAIRs | | deg | deg | (erg/s/cm^2) | | offset (in arcmin) | ----------------------------------------------------------------------------- EP J132305.4+015154 | 200.7724 | 1.865 | 4.7(+/-1.3) x 10^-14 | 4.0 | 6.64 | EP J132344.5+015453 * | 200.9355 | 1.9148 | 1.3(+/-0.3) x 10^-13 | 8.1 | 11.23 | EP J132351.8+015429 | 200.9659 | 1.908 | 7.8(+/-1.8) x 10^-14 | 5.1 | 12.13 | ----------------------------------------------------------------------------- Note: * EP J132344.5+015453 was also detected by Swift/XRT (GCN #40517) in a ~2.8 ks observation conducted at 2025-05-21T23:46:50, with a flux of ~2.4e-13 erg/s/cm^2. The source thus exhibits a decreasing trend in the X-ray flux within two epochs. The above observation was made with the EP-FXT instrument. 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/40532. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38563] GRB 250522B: Fermi GBM Final Localization
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40531 SUBJECT: GRB 250522B: Fermi GBM Final Localization DATE: 25/05/23 00:55:12 GMT FROM: Matt Godwin <msg0028(a)uah.edu> The Fermi GBM team reports the detection of a likely LONG GRB "At 17:08:52.84 UT on 22 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250522B (trigger 769626537/250522714). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 285.32, Dec = -54.30 (J2000 degrees, equivalent to J2000 19h 1m, -54d 17'), with a statistical uncertainty of 11.40 degrees. The angle from the Fermi LAT boresight is 80 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250522714/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250522714/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250522714/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/40531. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38562] GRB 250521D: SVOM/VT optical observations
by GCN Circulars 23 May '25

23 May '25

TITLE: GCN CIRCULAR NUMBER: 40530 SUBJECT: GRB 250521D: SVOM/VT optical observations DATE: 25/05/23 00:26:24 GMT FROM: Liping Xin at NAOC, SVOM <xlp(a)nao.cas.cn> W. Zheng (UCB), L. P. Xin, Y. L. Qiu, H. L. Li, C. Wu, Z. H. Yao, Y. N. Ma, X. H. Han, J. Wang (NAOC), Y. F. Liang (PMO), Z. Q. Wang (GXU) report on behalf of the SVOM/VT team: SVOM performed a Target of Opportunity observation of GRB 250521D detected by Fermi/GBM (Fermi GBM team, GCN 40516). SVOM/VT began observing the position of the counterpart candidate reported by LAST (Konno et al., GCN 40520) at 2025-05-22T05:58:37 UTC, 7.61 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. We clearly detected the candidate in VT both channels. The brightness in AB magnitude was estimated to be: Mid time (hour) | Band | Exposure Time (second) | Magnitude | Magnitude error 7.819 | VT_B | 15*100 | 19.66 | 0.02 7.819 | VT_R | 15*100 | 19.45 | 0.02 However, considering that there is no significant fading in brightness, and also this candidate was detected by GOTO (O'Neill et al., GCN 40522) before the GBM trigger, we also suggest that this candidate is an unrelated object. 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/40530. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38561] GRB 250522A: Fermi GBM Final Real-time Localization
by GCN Circulars 22 May '25

22 May '25

TITLE: GCN CIRCULAR NUMBER: 40529 SUBJECT: GRB 250522A: Fermi GBM Final Real-time Localization DATE: 25/05/22 22:12:30 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely SHORT GRB At 22:01:59 UT on 22 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250522A (trigger 769644124.77991 / 250522918). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 37.3, Dec = -5.4 (J2000 degrees, equivalent to J2000 02h 29m, -5d 24'), with a statistical uncertainty of 16.9 degrees. The angle from the Fermi LAT boresight is 60.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250522918/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250522918/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250522918/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40529. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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