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

[vsnet-grb-info 39090] IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41039 SUBJECT: IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 25/07/08 18:56:33 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 25-07-08 at 14:05:19.54 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_BRONZE alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 1.6259 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/141112_11292662.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 25-07-08 Time: 14:05:19.54 UT RA: 222.71 (+0.52/-0.54 deg 90% PSF containment) J2000 Dec: 26.49 (+0.47/-0.47 deg 90% PSF containment) J2000 We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino. No known gamma-ray sources listed in the Fermi 4FGL-DR4 or 3FHL catalogs are located within the 90% uncertainty region of the event. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu View this GCN Circular online at https://gcn.nasa.gov/circulars/41039. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39089] GRB 250704B / EP250704a: VLA radio detection
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41038 SUBJECT: GRB 250704B / EP250704a: VLA radio detection DATE: 25/07/08 17:46:51 GMT FROM: Genevieve Schroeder at Cornell University <genevieveschroeder(a)u.northwestern.edu> G. Schroeder (Cornell), J. Rastinejad, W. Fong (Northwestern), T. Laskar (Utah) report: We observed the location of the short-duration GRB 250704B/EP 250704A (Wang et al., GCN 40940; Li et al., GCNs 40941, 40956, Frederiks et al., GCN 40972; Wang et al., GCN 40978; Shimizu et al., GCN 41025) with the Karl G. Jansky Very Large Array (VLA) in C configuration under program 25A-063 (PI Schroeder) at a mid time of 2025 July 8 at 09:57 UT (4.1 days post-burst) for 1.25 hours at a mean frequency of 6 GHz. In preliminary analysis, we detect a 20-sigma radio source with a flux density of ~150 microJy at the position: RA(J2000) = 20:03:29.511 Dec(J2000) = +12:01:23.31 with an uncertainty of ~0.2" in each coordinate. This position is consistent with the X-ray position (Li et al., GCNs 40941, 40956; Evans et al. GCN 40951, Salvaggio et al. GCN 40987) and optical position (Schneider et al., GCN 40942). At z=0.661 (An et al. GCN 40966), this corresponds to a rest-frame luminosity of ~ 2e30erg/s/Hz, on the bright end of typical short-duration Gamma-ray burst radio afterglow luminosities at a similar rest-frame time (e.g., Laskar et al. 2022). Further observations are planned to assess the variability of the radio source and its connection to GRB 250704B and EP250704A. We thank the VLA staff for quickly approving and executing these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/41038. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39088] Fermi GRB 250708A: Global MASTER-Net observations report
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41037 SUBJECT: Fermi GRB 250708A: Global MASTER-Net observations report DATE: 25/07/08 17:30:48 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-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 250708A ( Fermi GBM team, GCN 41028) errorbox 8298 sec after notice time and 8329 sec after trigger time at 2025-07-08 17:10:51 UT, with upper limit up to 17.4 mag. The observations began at zenith distance = 63 deg. The sun altitude is -17.2 deg. The galactic latitude b = 30 deg., longitude l = 33 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2929280 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 8359 | 2025-07-08 17:10:51 | MASTER-SAAO | (16h 44m 30.84s , +12d 39m 32.4s) | C | 60 | 17.2 | 8359 | 2025-07-08 17:10:51 | MASTER-SAAO | (16h 46m 19.84s , +12d 23m 56.8s) | C | 60 | 17.4 | 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/41037. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39087] IceCube Alert 250708.59: Global MASTER-Net observations report
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41036 SUBJECT: IceCube Alert 250708.59: Global MASTER-Net observations report DATE: 25/07/08 17:26:22 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-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) was pointed to the IceCube Alert 250708.59 (trigger No 11292662,14h 52m 41.28s , +26d 45m 18.0s, R=0.51) errorbox 10955 sec after notice time and 11017 sec after trigger time at 2025-07-08 17:08:56 UT, with upper limit up to 18.8 mag. Observations started at twilight. The observations began at zenith distance = 61 deg. The sun altitude is -16.8 deg. The galactic latitude b = 63 deg., longitude l = 39 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2929205 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 11047 | 2025-07-08 17:08:56 | MASTER-SAAO | (14h 49m 32.05s , +26d 51m 11.1s) | C | 60 | 18.1 | 11047 | 2025-07-08 17:08:56 | MASTER-SAAO | (14h 51m 28.75s , +26d 35m 32.5s) | C | 60 | 18.0 | 11275 | 2025-07-08 17:12:44 | MASTER-SAAO | (14h 51m 31.65s , +26d 35m 43.8s) | C | 60 | 17.9 | 11335 | 2025-07-08 17:12:44 | MASTER-SAAO | (14h 51m 31.65s , +26d 35m 43.8s) | C | 180 | 18.7 | Coadd 11275 | 2025-07-08 17:12:44 | MASTER-SAAO | (14h 49m 32.60s , +26d 51m 19.6s) | C | 60 | 18.0 | 11335 | 2025-07-08 17:12:44 | MASTER-SAAO | (14h 49m 32.59s , +26d 51m 19.6s) | C | 180 | 18.8 | Coadd 11369 | 2025-07-08 17:14:18 | MASTER-SAAO | (14h 51m 34.49s , +26d 37m 22.8s) | C | 60 | 18.0 | 11369 | 2025-07-08 17:14:18 | MASTER-SAAO | (14h 49m 35.36s , +26d 52m 58.0s) | C | 60 | 18.1 | 11462 | 2025-07-08 17:15:51 | MASTER-SAAO | (14h 51m 29.28s , +26d 36m 44.1s) | C | 60 | 18.0 | 11462 | 2025-07-08 17:15:51 | MASTER-SAAO | (14h 49m 30.14s , +26d 52m 18.7s) | C | 60 | 18.0 | 11584 | 2025-07-08 17:17:23 | MASTER-SAAO | (14h 49m 30.78s , +26d 53m 23.3s) | C | 120 | 18.4 | 11584 | 2025-07-08 17:17:23 | MASTER-SAAO | (14h 51m 29.90s , +26d 37m 48.8s) | C | 120 | 18.3 | 11737 | 2025-07-08 17:19:56 | MASTER-SAAO | (14h 49m 37.53s , +26d 52m 27.5s) | C | 120 | 18.4 | 11737 | 2025-07-08 17:19:56 | MASTER-SAAO | (14h 51m 36.64s , +26d 36m 53.2s) | C | 120 | 18.3 | 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/41036. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39086] IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41035 SUBJECT: IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/07/08 17:20:16 GMT FROM: Jessie Thwaites at IceCube/U Wisc-Madison <thwaites(a)wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-250706A (https://gcn.nasa.gov/circulars/40994) in a time range of 1000 seconds centered on the alert event time (2025-07-06 13:06:20.040 UTC to 2025-07-06 13:23:00.040 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-250706A. We report a p-value of 1.00 in this time window. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-250706A is 1.5e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 6e+04 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2025-07-05 13:14:40.040 UTC to 2025-07-07 13:14:40.040 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-250706A is 1.8e-01 GeV cm^-2 in a 2 day time window. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/41035. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39085] LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41034 SUBJECT: LIGO/Virgo/KAGRA S250705cb: Updated Sky localization DATE: 25/07/08 16:03:00 GMT FROM: lucy.thomas(a)ligo.org The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S250705cb (GCN Circular 40980). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250705cb For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 333 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1143 +/- 299 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/41034. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39084] LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41033 SUBJECT: LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification DATE: 25/07/08 15:59:56 GMT FROM: lucy.thomas(a)ligo.org The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S250704ab (GCN Circular 40935). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250704ab Based on posterior support from parameter estimation [1], under the assumption that the candidate S250704ab is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [2] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [2] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The probability that the lighter compact object is below 1 solar mass (HasSSM) is <1%. The source chirp mass falls with highest probability in the bin (5.5, 11.0) solar masses after parameter estimation [1], assuming the candidate is astrophysical in origin. For the Bilby.multiorder.fits,0 sky map, the 90% credible region is well fit by an ellipse with an area of 57 deg2 described by the following DS9 region (right ascension, declination, semi-major axis, semi-minor axis, position angle of the semi-minor axis): icrs; ellipse(05h40m, +44d43m, 7.74d, 2.35d, 77.56d) Marginalized over the whole sky, the a posteriori luminosity distance estimate is 531 +/- 101 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 [2] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe View this GCN Circular online at https://gcn.nasa.gov/circulars/41033. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39083] LIGO/Virgo/KAGRA S250702n: Updated Sky localization
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41032 SUBJECT: LIGO/Virgo/KAGRA S250702n: Updated Sky localization DATE: 25/07/08 15:46:53 GMT FROM: lucy.thomas(a)ligo.org The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S250702n (GCN Circular 40884). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250702n For the Bilby.multiorder.fits,0 sky map, the 90% credible region is well fit by an ellipse with an area of 1926 deg2 described by the following DS9 region (right ascension, declination, semi-major axis, semi-minor axis, position angle of the semi-minor axis): icrs; ellipse(04h22m, -40d00m, 33.59d, 18.62d, 58.18d) Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2180 +/- 913 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/41032. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39082] LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41031 SUBJECT: LIGO/Virgo/KAGRA S250701bq: Updated Sky localization DATE: 25/07/08 15:39:52 GMT FROM: lucy.thomas(a)ligo.org The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S250701bq (GCN Circular 40880). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250701bq For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 25010 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 480 +/- 118 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/41031. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39081] EP250704a/GRB250704B : HCT optical and NIR upper limits
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41030 SUBJECT: EP250704a/GRB250704B : HCT optical and NIR upper limits DATE: 25/07/08 15:06:08 GMT FROM: V. Swain at IIT Bombay <vishwajeet.s(a)iitb.ac.in> V. Swain (IITB), D. Eappachen (IIA), T. Mohan (IITB), A.P. Saikia (IITB), D.K. Sahu (IIA), A. Balasubramanian (IIA), G. C. Anupama (IIA), V. Bhalerao (IITB), S. Barway (IIA), M. Nayana (IAO), S. Bandari (IAO) : We observed the field of EP250704a (Li et al., GCN 40941) also detected by SVOM (GRB 250704B; Wang et al., GCN 40940), with the 2.0m Himalayan Chandra Telescope (HCT) of the Indian Astronomical Observatory (IAO). We obtained multiple exposures in J and r' filters. We obtained the following upper limits: | JD (mid) | Date-Time (UTC)| Filter | Total Exposure (s) | tmid-t0 (days) | 5-sigma Upper Limit (AB) | | ---------------- |---------------- | ------ | ------------------ | -------------- | ---------------- | | 2460862.386666 | 2025-07-05T21:16:47.94 | J | 1170 | 1.54 | 18.9 | | 2460864.216936 | 2025-07-07T17:12:23.27 | r' | 3600 | 3.37 | 21.8 | The magnitudes are calibrated against PanSTARRS DR1 for SDDS r' filter (Chambers et al., 2016) and against 2MASS catalog (Skrutskie et al., 2006) for J-filter. The magnitudes are not corrected for Galactic extinction. The result is consistent with other optical observations. These observations were carried out under the ToO program HCT-2025-C2-P010. We thank the HCT staff for their support during the observations. The Indian Astronomical Observatory is operated by the Indian Institute of Astrophysics, Bengaluru, India. View this GCN Circular online at https://gcn.nasa.gov/circulars/41030. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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