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

[vsnet-grb-info 40732] Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42668 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB DATE: 25/11/13 14:29:46 GMT FROM: Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi(a)ba.infn.it> E. Bissaldi (Politecnico and INFN Bari) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 784717756 / 251113381 at 09:09:11.19 UT on 13 November 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to a solar flare." View this GCN Circular online at https://gcn.nasa.gov/circulars/42668. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40731] GRB 251112A: Swift/UVOT Upper Limits
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42667 SUBJECT: GRB 251112A: Swift/UVOT Upper Limits DATE: 25/11/13 14:23:39 GMT FROM: Alice Breeveld at MSSL-UCL <a.breeveld(a)ucl.ac.uk> A.A. Breeveld (UCL-MSSL) and A. Mei (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251112A 304 s after the BAT trigger (Mei et al., GCN Circ. 42656). No optical afterglow consistent with the XRT position (Lanava et al., GCN Circ. 42665) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u_FC 304 553 246 >19.9 white 856 944 86 >20.0 uvw1 683 697 14 >17.2 uvm2 658 849 39 >17.6 uvw2 609 801 39 >18.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.158 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42667. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40730] LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42666 SUBJECT: LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq DATE: 25/11/13 12:12:23 GMT FROM: James Gillanders at University of Oxford <jhgillanders.astro(a)gmail.com> J. H. Gillanders (Oxford), S. J. Smartt, K. W. Smith (Oxford/QUB), S. Srivastav, H. Stevance, F. Stoppa, A. Cooper (Oxford), M. Nicholl, D. R. Young, C. R. Angus, M. D. Fulton, T. Moore, A. Aamer, M. McCollum, S. Sim, J. Weston, X. Sheng, D. Magill, P. Ramsden (QUB), L. Shingles (GSI/QUB), L. Rhodes (TSI/McGill), L. Denneau, J. Tonry, H. Weiland, R. Siverd (IfA, University of Hawaii), N. Erasmus, W. Koorts (South African Astronomical Observatory), A. Rest (STScI), T.-W. Chen (NCU), C. Stubbs (Harvard), J. Sommer (LMU/QUB), B. Schmidt (ANU): We are currently observing the skymap of the LIGO/Virgo/KAGRA GW event S251112cm (LVK Collaboration, GCN 42650) with ATLAS (Tonry et al., 2018, PASP, 13, 164505; Licandro et al., 2023, arXiv:2302.07954). ATLAS is a quintuple 0.5-m optical telescope survey system (Hawaii x2, South Africa, Chile, Tenerife) employing three filters, cyan, orange and ‘clear’. In our primary NASA mission for Near-Earth Object discovery, we cover the entire visible night sky every 24 hours to a magnitude depth of m ~ 19.5, weather and Moon permitting. We will report our candidate discoveries in an upcoming GCN. Groot et al. (GCN 42663) report on BlackGEM/MeerLICHT observations of the GW skymap of S251112cm (GCN 42650), and they present two candidate counterparts: AT2025adgp and AT2025adgq. Here, we note that both AT2025adgp and AT2025adgq have historical detections in ATLAS, which precede the GW detection. The public ATLAS data (for these and any other transient) are accessible through the ATLAS Forced Photometry Server (Shingles et al. AstroNote #2021-7). More specifically: AT2025adgp was first detected on MJD 60991.136 (~0.5 days pre-GW) in the c-band with magnitude, m_c = 19.22 +/- 0.25 (AB) mag. AT2025adgq was first detected on MJD 60988.111 (~3.5 days pre-GW) in the o-band with magnitude, m_o = 19.03 +/- 0.18 (AB) mag. Given these pre-detections, we expect that both AT2025adgp and AT2025adgq are young, rising supernovae, unrelated to the GW signal, S251112cm. However, the exact nature of the optical counterpart to a sub-solar-mass compact object merger event is uncertain, and so we cannot rule out that these transient phenomena are related in some way. Further monitoring of these candidate events will occur with ATLAS. The Asteroid Terrestrial-impact Last Alert System (ATLAS) project is primarily funded to search for Near-Earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogs from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889, and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, University of Oxford, the Queen's University Belfast, the Space Telescope Science Institute, the South African Astronomical Observatory, and The Millennium Institute of Astrophysics (MAS), Chile. View this GCN Circular online at https://gcn.nasa.gov/circulars/42666. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40729] GRB 251112A: Swift-XRT refined Analysis
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42665 SUBJECT: GRB 251112A: Swift-XRT refined Analysis DATE: 25/11/13 10:27:12 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Lanava (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: We have analysed 847 s of XRT data for GRB 251112A, from 90 s to 939 s after the Swift trigger. The data comprise 64 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The refined XRT position is RA, Dec = 274.0697, +24.1535 which is equivalent to: RA (J2000): 18h 16m 16.72s Dec(J2000): +24d 09' 12.5" with an uncertainty of 4.1 arcsec (radius, 90% confidence). The light curve can be modelled with a power-law decay with a decay index of alpha=3.14 (+0.34, -0.30). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 3.3 (+/-0.4). The best-fitting absorption column is 4.9 (+1.3, -1.1) x 10^21 cm^-2, in excess of the Galactic value of 1.8 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 2.2 x 10^-11 (1.1 x 10^-10) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 4.9 (+1.3, -1.1) x 10^21 cm^-2 Galactic foreground: 1.8 x 10^21 cm^-2 Excess significance: 4.6 sigma Photon index: 3.3 (+/-0.4) If the light curve continues to decay with a power-law decay index of 3.14, the count rate at T+24 hours will be 7.8 x 10^-9 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x 10^-19 (8.4 x 10^-19) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/01413695. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42665. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40728] GRB 251108C: AstroSat CZTI detection
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42664 SUBJECT: GRB 251108C: AstroSat CZTI detection DATE: 25/11/13 09:10:52 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), A. Goyal (IITB), A. Arya (IITB), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long-duration GRB 251108C. This burst was also detected by the Konus-Wind team (priv. comm.) T0(KW) = 23:08:03.415 UT. The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-11-08 23:07:57.38 UTC. The measured peak count rate associated with the burst is 250 (+36, -38) counts/s above the background in the combined data of all quadrants, with a total of 630 (+121, -124) counts. We caution that there is a 0.3 s readout dead time in CZT data during the burst which affects the calculated total counts. The local mean background count rate was 257 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 7.0 (+1.8, -1.6) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-11-08 23:07:56.96 UTC The measured peak count rate associated with the burst is 660 (+49, -53) counts/s above the background in the combined data of all quadrants, with a total of 3568 (+326, -374) counts. The local mean background count rate was 1128 (+7, -7) counts/s. Using cumulative rates, we measure a T90 of 10.9 (+3.2, -3.0) s. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/42664. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40727] LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42663 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq DATE: 25/11/13 08:46:10 GMT FROM: Paul Groot at Radboud University Nijmegen <p.groot(a)astro.ru.nl> P.J. Groot (Radboud/UCT/SAAO) , H. Tranin (Barcelona), J. van Roestel (ISTA), P.M. Vreeswijk (Radboud), D. Pieterse (Radboud), G. Leloudas (DTU Space), N. Blagorodnova (Barcelona), S. Bloemen (Radboud), G. Ramsay (Armagh), S. Scaringi (Durham) report on behalf of the BlackGEM and MeerLICHT consortia: "The BlackGEM and MeerLICHT telescopes (Groot et al., 2024) reacted to the LVK-announced gravitational wave event S251112cm (LVK2025, GCN Circ. 42650). Both telescope systems covered about 50% of the 90% error box, primarily the part located in the Southern Hemisphere. A detailed overview of observations will be given in a subsequent report. Here we report the detection of AT2025adgp (BGEM J014746.20-514925.5), and AT2025adgq (MLT J002931.8-393051.6) as two newly detected transients in the BlackGEM/MeerLICHT footprint, which, on average, had a limiting magnitude for new transients of q~19.8. AT2025adgp is located at RA, Dec (ICRS) = 01:47:46.202 -51:49:25.52 (26.942508d, -51.823756d) with an uncertainty of 0.1" in each coordinate. It was detected on 2025-11-13 03:09:48 and 03:25:29 UT in the BlackGEM q-band (440-720 nm) filter using the BG-2 telescope, at, respectively, q=19.31+/-0.12 and q=19.29+/-0.12. The first detection was 11h50m after the LVK Trigger time. The transient is located in the southern outskirts of a face-on spiral galaxy WISExSCOS J014746.23-514922.5, listed in the Regalade catalog (Tranin et al., 2025) at a luminosity distance of D_L =246 Mpc with a large standard deviation, and in the GLADE+ (Dalya et al., 2020) catalog at D_L = 250 +/- 45 Mpc. If the galaxy is the host of AT2025adgp this would put its distance at the upper edge of consistency with the distance to S251112cm as announced by the LVK collaboration at D_S251112cm = 96 +/- 29 Mpc. AT2025adgq is located at RA,Dec (ICRS) = 00:29:31.8, -39:30:51.6 (7.38245842d, -39.5143190d) with an uncertainty of 0.1” in each coordinate. It was detected on 2025-11-13 00:03:38 and 00:04:43 UT in the BlackGEM q-band (440-720 nm) filter using the MeerLICHT telescope at, q=19.28+/-0.10 in each exposure. The first detection was 08h44m after the LVK trigger. The BlackGEM array also detected AT2025adgq on 2025-11-13 01:05:23 UT and 01:22:00 UT using the BG-2 telescope at q=19.28 +/- 0.10 and q=19.41 +/- 0.1, respectively. The transient is located in the north-eastern elongation of an oblated galaxy, WISExSCOS J002932.49-393059.7, listed in the Regalade catalog at a luminosity distance of D_L = 279 +/- 130 Mpc, and in the GLADE+ catalog at D_L = 300 +/- 68 Mpc. If the galaxy is the host of AT2025adqp this would put its distance at the upper edge of consistency with the distance to S251112cm as announced by the LVK collaboration. We encourage spectroscopic classification of AT2025adgp and AT2025adgq to confirm their nature and distance, and therefore the possibility of them being a counterpart to S251112cm." References: Groot et al., 2024, PASP 136, 5003, Tranin et al., 2025, arXiv250813267T, Dalya et al., 2020, VizieR On-line Data Catalog: VII/275; LVK2025, 2025, GCN 42650 View this GCN Circular online at https://gcn.nasa.gov/circulars/42663. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40726] GRB 251112B: MAXI/GSC detection
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42662 SUBJECT: GRB 251112B: MAXI/GSC detection DATE: 25/11/13 03:24:59 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo(a)phys.aoyama.ac.jp> T. Kawamuro (Osaka U.), M. Nakajima (Nihon U.), Y. Kawakubo, M. Serino (AGU), H. Negoro, K. Takagi, H. Takahashi, 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, Y. Ishihara (Chuo U.), M. Shidatsu, C. Kang, T. Nakamoto, M. Uenishi, T. Usuki, S. Yatsuzuka (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.), S. Yamada (Tohoku U) report on behalf of the MAXI team: The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 20:54:12 UT on November 12, 2025. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (278.962 deg, 18.196 deg) = (18 35 50, +18 11 45) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.30 deg and 0.26 deg, respectively. The roll angle of long axis from the north direction is 99.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 146 +- 34 mCrab (4.0-10.0keV, 1 sigma error). Without assumptions on the source constancy, we obtain a rectangular error box for the transient source with the following corners: (R.A., Dec) = (277.696, 16.760) deg = (18 30 47, +16 45 36) (J2000) (R.A., Dec) = (278.212, 16.464) deg = (18 32 50, +16 27 50) (J2000) (R.A., Dec) = (279.748, 18.876) deg = (18 38 59, +18 52 33) (J2000) (R.A., Dec) = (279.227, 19.177) deg = (18 36 54, +19 10 37) (J2000) There was no significant excess flux in the previous transit at 19:21 UT and in the next transit at 22:27 UT with an upper limit of 20 mCrab for each. View this GCN Circular online at https://gcn.nasa.gov/circulars/42662. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40725] Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42661 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB DATE: 25/11/13 02:41:40 GMT FROM: Lorenzo Scotton at UAH <lscottongcn(a)outlook.com> L. Scotton (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 784687703/251113034 at 00:48:18.02 UT on 13 November 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to distant particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/42661. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40724] Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42660 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB DATE: 25/11/13 02:40:53 GMT FROM: Lorenzo Scotton at UAH <lscottongcn(a)outlook.com> L. Scotton (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 784687099/251113027 at 00:38:14.12 UT on 13 November 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to distant particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/42660. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40723] LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
by GCN Circulars 13 Nov '25

13 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42659 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations DATE: 25/11/13 02:29:27 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo(a)phys.aoyama.ac.jp> H. Hiramatsu, S. Sugita, M. Serino, Y. Kawakubo, Y. Kondo (AGU) H. Negoro, M. Nakajima, K. Takagi (Nihon U.), N. Kawai, T. Mihara, (RIKEN), report on behalf of the MAXI team: We examined MAXI/GSC all-sky X-ray images (2-20 keV) after compact binary merger candidate S251112cm at 2025-11-12 15:18:45.362 UTC (GCN #42650). At the trigger time of S251112cm, the high-voltage of MAXI/GSC was on. The instantaneous field of view of GSC at the GW trigger time covered 1% of the 90% credible region of the bayestar sky map, in which we found no significant new X-ray source. The first one-orbit (92 min) scan observation with GSC after the event covered 72% of the 90% credible region of the bayestar skymap from 15:18:45 to 16:50:09 UTC (T0+0 to T0+5484 sec). No significant new source was found in the region in the one-orbit scan observation. A typical 1-sigma averaged upper limit obtained in one scan observation is 20 mCrab at 2-20 keV. If you require information about X-ray flux by MAXI/GSC at specific coordinates, please contact the submitter of this circular by email. View this GCN Circular online at https://gcn.nasa.gov/circulars/42659. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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