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

[vsnet-grb-info 39170] Swift Trigger 1334535: a possible GRB 250718A
by GCN Circulars 18 Jul '25

18 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41115 SUBJECT: Swift Trigger 1334535: a possible GRB 250718A DATE: 25/07/18 00:47:35 GMT FROM: Mike Siegel at PSU/Swift MOC <siegel(a)swift.psu.edu> M. H. Siegel (PSU), R. Gupta (NASA GSFC), S. Lanava (PSU), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 00:14:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located possible GRB 250718A (trigger=1334535). The BAT on-board calculated location is RA, Dec 241.998, -11.993 which is RA(J2000) = 16h 07m 59s Dec(J2000) = -11d 59' 35" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a sharp rise with a duration of just a few milliseconds. The peak count rate was ~1070 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to an observing constraint, Swift will not slew to the burst until 01:07 UT. Due to the marginal significance of the BAT image (6.85 sigma), and the lack of prompt XRT and UVOT data, this trigger may be due to a noise fluctuation. Further data are required to determine the nature of this trigger. Burst Advocate for this burst is M. H. Siegel (siegel AT swift.psu.edu) Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/41115. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39169] Swift GRB250718.01: Global MASTER-Net observations report
by GCN Circulars 18 Jul '25

18 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41114 SUBJECT: Swift GRB250718.01: Global MASTER-Net observations report DATE: 25/07/18 00:18:39 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) was pointed to the Swift GRB250718.01 (trigger No 1334535,16h 07m 59.47s , -11d 59m 35.9s, R=0.05) errorbox 16 sec after notice time and 35 sec after trigger time at 2025-07-18 00:14:38 UT, with upper limit up to 19.0 mag. The observations began at zenith distance = 22 deg. The sun altitude is -30.2 deg. The galactic latitude b = 28 deg., longitude l = 1 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2939309 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 41 | MASTER-OAFA | C | 10 | 19.0 | 57 | MASTER-OAFA | C | 10 | 19.0 | 73 | MASTER-OAFA | C | 10 | 19.0 | 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/41114. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39168] GRB 250717B: Swift ToO observations
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41113 SUBJECT: GRB 250717B: Swift ToO observations DATE: 25/07/17 21:29:37 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the Fermi/GBM-detected event GRB 250717B. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021846 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 Fermi/GBM 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/41113. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39167] EP270713a: Kitab and AbAO Optical Observations
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41112 SUBJECT: EP270713a: Kitab and AbAO Optical Observations DATE: 25/07/17 20:04:29 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), A. Pozanenko (IKI), A. Schmalz (KIAM), R. Ya. Inasaridze (AbAO) and A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We observed the field of GRB 250713A detected by SVOM/ECLAIRs (Maggi et. al, GCN 41078) using the RC-36 telescope of the ISON-Kitab Observatory and the AS-32 telescope of the Abastumani Observatory (AbAO). The observations at Kitab began on 2025-07-13 at 19:29 UT, i.e. ~0.13 days after the trigger, while AS-32 started observations 2025-07-13 at 19:59 UT, i.e. ~0.14 days since trigger. We obtained a series of 120x60 sec images in the clear light with RC-36 and a series of 71x60 sec images in the R-band with AS-32. We have inspected the co-added images from both telescopes for any new optical sources spatially consistent with the X-ray candidates found by EP-FXT (Liang et. al, GCN 41085) and Swift/XRT (Evans et. al, GCN 41086). No new optical sources were found in our observations. However, our searches revealed one known, but brightened optical source J222746.80+384743.9 from the SDSS-DR12 catalog found within the localization of EPF_J222746.7+384738 (90% error radius is 10 arcsec). The magnitudes of J222746.80+384743.9 in SDSS-DR12 are g = 21.54 +/- 0.06 and r = 20.58 +/- 0.04, and i = 20.13 +/- 0.04, which can be transformed by Lupton 2005 transformation into R = 20.31 +/- 0.11. The preliminary photometry of SDSS J222746.80+384743.9 is provided below: Date UT start t-T0 Exp. Filter OT Err. UL Telescope (mid, days) (n*s) (3sigma) 2025-07-13 19:29:20 0.13431 101*60 R n/d n/d 18.5 Kitab 2025-07-13 19:59:02 0.14313 67*60 R 19.28 0.14 19.7 AS-32 The photometry was calibrated using nearby stars from the SDSS-DR12 catalog (R-mags obtained with Lupton 2005 transformations) and not corrected for the Galactic extinction. We can tentatively assume that SDSS J222746.80+384743.9 is a stellar flare if indeed the gamma-ray and X-ray emission came from SDSS J222746.80+384743.9. The optical source reported by NOT (Saccardi et. al, GCN 41091) was not detected by our telescopes. Ref. stars SDSS-DR12 RA Dec R(Lupton 2005 transformation) 336.9314 38.7641 14.28 336.9030 38.7712 16.08 336.9267 38.7809 15.76 336.9080 38.7704 16.35 View this GCN Circular online at https://gcn.nasa.gov/circulars/41112. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39166] GRB 250717B: Fermi GBM Observation
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41111 SUBJECT: GRB 250717B: Fermi GBM Observation DATE: 25/07/17 18:59:30 GMT FROM: Jacob Smith at Fermi-GBM Team <jrs0118(a)uah.edu> Jacob Smith (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 13:44:22.95 UT on 17 July 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250717B (trigger 774452667/250717572). which was also detected by Swift/BAT-GUANO (Samuele Ronchini et al. 2025, GCN 41110). The Fermi GBM on-ground location is consistent with the Swift/BAT-GUANO position. The angle from the Fermi LAT boresight is 74 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 6.4 s (50-300 keV). The time-averaged spectrum from T0+0.002 to T0+7.360 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.9 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 75 +/- 5 keV. A Band function fits equally well with Epeak = 72 +/- 6 keV, alpha = -0.9 +/- 0.2 and beta = -3.2 +/- 0.9. The event fluence (10-1000 keV) in this time interval is (1.36 +/- 0.05)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.13 s in the 10-1000 keV band is 6.1 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/41111. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39165] GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41110 SUBJECT: GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst DATE: 25/07/17 16:46:46 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (PSU) report: Swift/BAT did not localize GRB 250717B onboard (T0: 2025-07-17T13:44:22 UTC, Fermi GCN 41107). The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The position is found with the newly developed pipeline BAT-GLIMPSE: Gamma-ray Localization using Imaging and Mosaic techniques for Pointing and Slew Epochs (Ronchini et. al, in prep). The pipeline makes use of the tools from BatAnalysis ([Parsotan et al. 2025](https://iopscience.iop.org/article/10.3847/1538-4357/ade240)) The source is found with an SNR = 26.3. The BAT position is: RA, Dec = 44.1179, 26.3789 deg which is RA(J2000) = 02h 56m 28.30s Dec(J2000) = 26d 22’ 44.0″ with an estimated uncertainty of 3 arcmin radius. More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=774452698 XRT and UVOT follow-up has been requested. Results of follow-up observations will be reported in future circulars. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/41110. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39164] Konus-Wind detection of GRB 250716A
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41109 SUBJECT: Konus-Wind detection of GRB 250716A DATE: 25/07/17 15:32:45 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The bright, long-duration GRB 250716A (Fermi-GBM detection: Fermi GBM team, GCN 41099; Mukherjee and Meegan, GCN 41102) triggered Konus-Wind at T0=5348.122 s UT (01:29:08.122). The burst light curve shows a multipeaked structure which starts at ~T0-91 s and has a total duration of ~235 s. The emission is seen up to ~20 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250716_T05348/ As observed by Konus-Wind, the burst had a fluence of 2.39(-0.09,+0.09)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+2.544 s, of 4.26(-0.33,+0.33)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+88.064 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.25(-0.04,+0.04), the high energy photon index beta = -1.78(-0.04,+0.03), the peak energy Ep = 554(-84,+93) keV (chi2 = 124/97 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+4.096 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.78(-0.06,+0.07), the high energy photon index beta = -1.59(-0.03,+0.03), the peak energy Ep = 726(-113,+139) keV (chi2 = 106/86 dof). All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/41109. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39163] GRB 250716A: Swift-XRT afterglow detection
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41108 SUBJECT: GRB 250716A: Swift-XRT afterglow detection DATE: 25/07/17 15:12:43 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M.A. Williams (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), A. Melandri (INAF-OAR) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/GBM-detected burst GRB 250716A. We searched for X-ray sources in 2.6 ks of Photon Counting (PC) mode data. The total exposure at the position of the afterglow (see below) is 2.6 ks, obtained between T0+79.5 ks and T0+91.7 ks. An uncatalogued X-ray source is detected within the GOTO error region and is above the RASS 3-sigma upper limit at this position, and is therefore likely the GRB afterglow. Using 2790 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 66.77171, -46.56649 which is equivalent to: RA (J2000): 04h 27m 05.21s Dec(J2000): -46d 33' 59.4" with an uncertainty of 2.7 arcsec (radius, 90% confidence). This position is 1.9 arcsec from the GOTO position. The light curve can be modelled with a power-law decay with a decay index of alpha=2.755 (+0.015, -0.755). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.22 (+0.30, -0.27). The best-fitting absorption column is 6.9 (+6.4, -5.2) x 10^20 cm^-2, in excess of the Galactic value of 1.2 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.0 x 10^-11 (3.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 6.9 (+6.4, -5.2) x 10^20 cm^-2 Galactic foreground: 1.2 x 10^20 cm^-2 Excess significance: 1.8 sigma Photon index: 2.22 (+0.30, -0.27) The results of the XRT-team automatic analysis of the likely afterglow are at https://www.swift.ac.uk/ToO_GRBs/00021845/Source1.php. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021845. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/41108. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39162] GRB 250717B: Fermi GBM Final Real-time Localization
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41107 SUBJECT: GRB 250717B: Fermi GBM Final Real-time Localization DATE: 25/07/17 13:54:55 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 13:44:22 UT on 17 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250717B (trigger 774452667.945704 / 250717572). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 44.4, Dec = 20.9 (J2000 degrees, equivalent to J2000 02h 57m, 20d 53'), with a statistical uncertainty of 3.8 degrees. The angle from the Fermi LAT boresight is 70.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250717572/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250717572/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250717572/… View this GCN Circular online at https://gcn.nasa.gov/circulars/41107. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39161] GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41106 SUBJECT: GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp DATE: 25/07/17 11:01:22 GMT FROM: Amit Kumar at Royal Holloway - UoL/ U of Warwick, UK <amitkundu515(a)gmail.com> Amit Kumar (RHUL), Nikita Rawat (SAAO), David Buckley (SAAO), Justyn R. Maund (RHUL), Danny Steeghs (Warwick) and Raya Dastidar (UNAB) report: We observed the optical transient GOTO25eyp (AT 2025rhc; Rayson et al., GCN 41103), a candidate counterpart to GRB 250716A (Fermi GBM Team, GCNs 41099, 41102), using the 1-m Lesedi telescope at the South African Astronomical Observatory (SAAO), Sutherland, South Africa. Observations were conducted on 2025 July 17 between 03:08:39 and 04:09:30 UT (~25.66 to ~26.67 hours post-trigger) in g’, r’, i’, and z’ bands (3×360s in g and z, 3×300s in r and i bands). GOTO25eyp was clearly detected in all individual exposures across the four filters. Preliminary aperture photometry yields the following magnitudes in g’ and r’ bands: DATE-OBS T-T0 (hrs) Filter Exp (s) Magnitude (AB) ------------------------------------------------------------------------------------- 2025-07-17T03:08:39 25.66 g’ 360s 18.95 ± 0.09 2025-07-17T03:26:56 25.96 r’ 300s 18.67 ± 0.07 These observations indicate a decline of ~0.6 mag over ~8.4 hours since the initial detection reported by GOTO. This fading behaviour suggests a transient origin for GOTO25eyp and is broadly consistent with the temporal evolution expected from a GRB afterglow. We note that we are considering the GOTO L-band (400–700 nm), which approximates the mean wavelength coverage of the g and r filters. Photometric calibration was performed using reference stars from the SDSS catalogue. Follow-up observations are ongoing, and further analysis is in progress. Data were obtained using the 1-m Lesedi robotic telescope at the SAAO, equipped with the Mookodi low-resolution spectrograph and imager operating in fully robotic imaging mode. We thank the SAAO Instrumentation and Operations (IO) team for their continued support. View this GCN Circular online at https://gcn.nasa.gov/circulars/41106. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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