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[vsnet-grb-info 38969] GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
by GCN Circulars 03 Jul '25

03 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40923 SUBJECT: GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation DATE: 25/07/03 16:44:09 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Alexis Coleiro (APC) Report on behalf of the SVOM team: On July 2, 2025, SVOM/GRM detected a hard X-ray activity using event-by-event data downloaded via the X-band ground station. This activity is consistent with detections reported by Fermi/GBM (Fermi GBM Team, GCN #40883, #40885, #40886, #40890, #40891), Swift/BAT (James DeLaunay et al., GCN #40903), and Konus-Wind (D. Frederiks et al., GCN #40914). These transient events may be associated with the soft X-ray transient EP250702a (GCN #40906), also detected by MAXI/GSC (GCN #40910). At the time of the hard X-ray triggers, the refined position reported by EP/WXT (R.A. = 284.6911 deg, DEC = -7.8715 deg J2000, GCN#40906) was approximately 48 degrees from the SVOM optical axis, which is just outside the ECLAIRs field of view. GRD 02 and GRD 03 provided continuous coverage of this transient activity (with incident angle of 30 and 48 degrees, respectively) from the very beginning to about 2025-07-02T15:20:00, except passing the SAA and Earth’s shadow. The SVOM/GRM light curve of GRB 250702D can be found here: https://www.bursthub.cn//admin/static/svgrb250702D.png We note that the report here is very preliminary, refined analysis is still ongoing. 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. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/40923. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38968] GRB 250702A: GECAM-B detection
by GCN Circulars 03 Jul '25

03 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40922 SUBJECT: GRB 250702A: GECAM-B detection DATE: 25/07/03 16:26:33 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by the long burst GRB 250702A at 2025-07-02T09:54:07.850 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN#40881). According to the GECAM-B light curves in about 40-6000 keV, this burst mainly consists of a single pulse with a duration (T90) of 24.0 +2.5/-4.5 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecamgrb250702A.png This burst is incident from the back of satellite platform and the on-ground localization is subject by the Earth shadow of Fermi/GBM. With the localization from Fermi/GBM (RA=317.8, DEC=48.1, GCN#40881). The time-averaged spectrum from T0-2 s to T0+31 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.91 +0.20/-0.16 and the cutoff energy, parameterized as Epeak, is 417 +136/-93 keV. The event fluence (10-1000 keV) in this time interval is (3.85 +0..35/-0.41)E-05 erg/cm^2. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/40922. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38967] GRB 250702F: Skynet Optical Observations
by GCN Circulars 03 Jul '25

03 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40921 SUBJECT: GRB 250702F: Skynet Optical Observations DATE: 25/07/03 16:24:13 GMT FROM: Dylan Dutton at UNC Chapel Hill <ddutton59(a)gmail.com> Dylan Dutton, Daniel Reichart, Joshua Haislip, Vladimir Kouprianov, Staszek Zola, Tyler Linder, and Jonathan Keohane report on behalf of the Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill. We observed the field of GRB 250702F detected by Swift (Siegel, GCN 40894) with one of Skynet's PROMPT telescopes located at the Astronomical Observatory of the Jagiellonian University, two of Skynet's PROMPT telescopes located at the Cerro Tololo Inter-American Observatory, and a 0.4m telescope located at Hampden-Sydney College. Observations began roughly 2.5 minutes post trigger and continued for 8 hours. We detect the optical afterglow (Siegel, GCN 40894; Jelinek, GCN 40895; Kumar GCN 40896; Lipunov GCN 40899; Martin-Carrillo GCN 40900; Talamantes GCN 40907; Becerra GCN 40911; Brivio GCN 40913; An GCN 40916) in the B, V, R, I, and r bands. We report the initial detection photometry below. Inspection of the first 2.5 hours of photometry indicates a fading from ~15.5 mag (two minutes post-trigger) to ~18 mag (two-hours post-trigger) in R band. The light curve appears to plateau for the remaining 30 minutes. Analysis of the additional 5.5 hours of photometry is ongoing. Exposure lengths were calculated using our automated exposure length scaling model. Tmid - T0 (s) | Telescope | Filter | Exposure (s) | Mag | Mag Error ------------------------------------------------------------------------ 153 | PROMPT-OAUJ | V | 2 | 15.454 | 0.101 168 | PROMPT-OAUJ | R | 2 | 15.447 | 0.118 Our images have been calibrated using stars from the APASS catalog. Magnitudes were not corrected for dust extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40921. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38966] GRB 250424A: VIRT Optical Upper Limit
by GCN Circulars 03 Jul '25

03 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40920 SUBJECT: GRB 250424A: VIRT Optical Upper Limit DATE: 25/07/03 15:22:30 GMT FROM: Priya Gokuldass at ERAU <gokuldap(a)my.erau.edu> K. Smith (UVI), P. Gokuldass (ERAU), N. Orange (OrangeWave Innovative Science, LLC), B. Gendre (UVI), D. Morris (NASA), T. Lombardi (Eckerd College), F. George (ERAU), D. Smith (UVI), C. Watson (UVI) report: We observed the field of GRB 250424A (Cenko et al., GCN 40224) detected by Swift/BAT with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 2025-05-06 starting at 02:22:01.68 UTC (T-mid ~ T0 + 7d 3.45h). We performed a series of exposures in an R filter with a total exposure of 2860s. The weather conditions were partly cloudy during the hours of observation with an average airmass of 1.8. We do not detect any source at the enhanced XRT position reported (Evans et al., GCN 40232). This non-detection is consistent with reported detections (Francile et al., GCN 40222; Brivio et al., GCN 40225; de Wet et al., GCN 40229; Becerra et al., GCN 40226; Saccardi et al., GCN 40228; Siegel et al., GCN 40244; Dutton et al., GCN 40241; Schneider et al., GCN 40250; Ducoin et al., GCN 40230; Turpin et al., GCN 40240; Elkabir et al., GCN 40251; Ghosh et al., GCN 40263; de Ugarte Postigo et al., GCN 40461 ) and upper limits (Lipunov et al., GCN 40223; Siegel et al., GCN 40244). We report the following 3-sigma upper limit: T_mid ||Exposure ||Filter ||Limit T+ 7d 3.45h || 2860 s || R ||> 20.7 The limit is estimated from comparison to nearby USNO B1 stars and is not corrected for Galactic extinction. We acknowledge financial support from NASA EPSCoR award 80NNSC22M0063, NSF PAARE award 2319415, and NASA EPSCoR award 80NSSC24M0112. This message can be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40920. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38965] GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
by GCN Circulars 03 Jul '25

03 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40919 SUBJECT: GRBs 250702B/C/D/E / EP250702a: Swift XRT localization DATE: 25/07/03 15:14:48 GMT FROM: Jamie Kennea at Penn State <jak51(a)psu.edu> J. A. Kennea, M. H. Siegel (PSU), P. A. Evans, K. L. Page (Leicester) and B. O'Connor (CMU) report on behalf of the Swift Team: Swift began an TOO observation of the Einstein Probe (GCN #40906) of this source that showed repeated outbursts detected by Fermi/GBM (GCN #40883, #40885, #40886, #40890, #40891) and Swift/BAT-GUANO (GCN #40903) on July 3, 2025 at 01:34UT. We detect a bright uncatalogued X-ray point source at the following localization: RA/Dec(J2000) = 284.69006, -7.87413 which is equivalent to: RA(J2000) = 18h 58m 45.61s, Dec(J2000) = -07d 52' 26.9'', with an estimated error uncertainty of 2.0 arc-seconds radius (90% confidence). This position is not coincident with any UVOT detected source. The X-ray flux during the Swift TOO observation is highly variable, showing a rapid fading behavior during the first orbit of data, suggesting the tail end of a flare, with the average rate over the orbit of 1.5 +/- 0.1 c/s. Following orbits the source has count rate between of 0.4-0.5 c/s. The spectrum is well fit by an absorbed power law with N_H = 1.1 +/- 0.2 x 10^22 cm^-2, and a photon index of 1.65 +/- 0.20. The average flux of the source is 4.5 +/- 0.4 10^-11 erg/s/cm^2 (0.3-10 keV) observed, and 6.8 (+0.9/-0.6) x 10^-11 erg/s/cm^2 (0.3 - 10 keV) corrected for absorption. Further Swift observations of this object are planned. Follow-up observations to classify the source are highly encouraged. View this GCN Circular online at https://gcn.nasa.gov/circulars/40919. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38964] GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
by GCN Circulars 03 Jul '25

03 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40918 SUBJECT: GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit DATE: 25/07/03 15:12:02 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Rosa L. Becerra (U Roma), Damien Dornic (CPPM), Margarita Pereyra (UNAM), Jean-Luc Atteia (IRAP), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Fredd Alvarez (UNAM), Camila Angulo (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), Nathaniel R. Butler (ASU), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We imaged the field of the likely ULGRB detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 40883, 40885, 40886, 40890, 40891) specifically at the position of EP250702a (Cheng et al., GCN Circ. 40906) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-07-03 08:19 to 09:45 UTC, from 29.4 to 30.9 hours after the EP/WXT trigger (Cheng et al., GCN Circ. 40906) and obtained 64 minutes of exposure in the i filter. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. In the stacked image and after performing image subtraction, we do not detect any new source at the EP/FXT source position (Cheng et al., GCN Circ. 40906) down to the following 3-sigma limit: i > 22.0 This upper limit is consistent with the one reported by GOTO (Kumar et al. GCN Circ. 40908) We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/40918. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38963] EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
by GCN Circulars 03 Jul '25

03 Jul '25

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 <ep_ta(a)bao.ac.cn> 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(a)nao.cas.cn) and Yi-Jia Zhang (zhangyij21(a)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. View this GCN Circular online at https://gcn.nasa.gov/circulars/40917. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38962] GRB 250702F: TRT Optical Observation
by GCN Circulars 03 Jul '25

03 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40916 SUBJECT: GRB 250702F: TRT Optical Observation DATE: 25/07/03 14:23:55 GMT FROM: Zipei Zhu at NAOC <zpzhu(a)nao.cas.cn> J. An (NAOC), K. Noysena, K. Chanchaiworawit, S. Tinyanont (NARIT), S.Y. Fu (HUST), X. Liu, Z.P. Zhu, S.Q. Jiang, L.B. He, D. Xu (NAOC) report on behalf of a large collaboration: We observed the field of GRB 250702F detected by Swift/BAT (Klingler et al., GCN 40894) and Fermi/GBM (Fermi GBM Team, GCN 40892), using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at Fresno, California, U.S.A. (SRO). Observations started at 05:17:25 UTC on 2025-07-03, i.e., ~ 8.18 hr after the Swift/BAT trigger and several frames in the R & I band were obtained. We clearly detect the optical afterglow (Jelinek et al., GCN 40895; Kumar et al., GCN 40896; Lipunov et al., GCN 40899; Martin-Carrillo et al., GCN 40900; Angulo et al., GCN 40907; Becerra et al., GCN 40911; Brivio et al., GCN 40913) in our images. Preliminary photometry shows that the source has R ~ 19.4 mag at 8.32 hr post-trigger and I ~ 18.6 mag at 8.61 hr post-trigger, calibrated with Pan-STARRS DR2 catalog and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40916. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38961] GRB 250703A: DDOTI Optical Upper Limit
by GCN Circulars 03 Jul '25

03 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40915 SUBJECT: GRB 250703A: DDOTI Optical Upper Limit DATE: 25/07/03 14:00:42 GMT FROM: sahil.atri(a)students.uniroma2.eu Sahil Atri (U Roma), Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), Margarita Pereyra (UNAM) and Eleonora Troja (U Roma) report: We observed the field of GRB 250703A detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 40909) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir (http://ddoti.astroscu.unam.mx) on the night of 2025-07-03 UTC. DDOTI observed the Fermi/GBM error region, covering about 92% of the statistical error region (Fermi GBM Team, GCN Circ. 40909). DDOTI observed the field of GRB 250703A from 09:19 UTC to 11:22 UTC (from T+ 0.2 h to T+ 2.2 h after the trigger) and obtained a total exposure of 56 minutes, alternating with other scientific programs. Comparing our observations to the USNO-B1 and Pan-STARRS PS1 DR2 catalogues, we detect no uncatalogued fading sources within the observed field down to a 10-sigma limiting AB magnitude of: w > 20.8 This value is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40915. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38960] GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
by GCN Circulars 03 Jul '25

03 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40914 SUBJECT: GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity DATE: 25/07/03 12:51:12 GMT FROM: Dmitry Frederiks at Ioffe Institute <fred(a)mail.ioffe.ru> D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: On July 2, 2025, Konus-Wind (KW) detected, in the waiting mode, a hard X-ray activity, consistent in time with GRBs 250702B, C, D, E, reported by Fermi-GBM team (GCN 40883, 40885, 40886, 40890, 40891), localized by Swift/BAT-GUANO (GCN 40903), associated with the X-ray transient EP250702a (GCN 40906), and detected by MAXI/GSC (GCN 40910). KW observed multiple overlapped emission episodes in in the time interval from ~12:40 to ~16:50 UT. The emission is clearly visible in all three KW waiting mode energy bands (20-75, 75-300, 300-1250 keV). From our preliminary background estimates, the total duration of the event is >~15.5 ks. The Konus-Wind light curve is available at http://www.ioffe.ru/LEA/GRBs/GRB250702BCDE/ In the 20-1250 keV range, the time-integrated spectrum of the emission is best described by a simple power law (PL) function with the PL photon index of (-1.3 ± 0.06). The total observed fluence in this energy band is (5.95 ± 0.32)x10^-4 erg/cm^2 and the 2.944 s peak energy flux is (5.33 ± 0.29)x10^-7 erg/cm^2/s. All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/40914. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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