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

[vsnet-grb-info 38026] GRB 250327B: Kilonova-Catcher Observations
by GCN Circulars 02 Apr '25

02 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40006 SUBJECT: GRB 250327B: Kilonova-Catcher Observations DATE: 25/04/02 01:27:54 GMT FROM: Cristina Andrade at UMN <andra104(a)umn.edu> E. Broens, F. Dubois, M. Freeberg, A. Lekic, G. Parent, M. Serrau (KNC), C. Andrade (UMN), E. de Bruin (UMN), D. Turpin (CEA-Saclay/Irfu), S. Antier (OCA), M. Coughlin (UMN),S. Karpov (FZU), I. Tosta e Melo (UniCT-DFA), P. Hello (IJCLAB), P-A Duverne (APC), T. Pradier (Unistra/IPHC), N. Guessoum (AUS) on behalf of the GRANDMA/Kilonova-Catcher collaboration: We observed the field of GRB 250327B (Bouchet et al., GCN 39888) detected by SVOM/ECLAIRs with the citizen science project, Kilonova-Catcher (KNC). These observations were performed by our members using the following telescopes: T-BRO, ODK16 f/6.8, Quatro F4, T180, a Newton telescope T200 and using the Telescope Live Network. In our stacked frames, we detected an optical afterglow at the position reported by SAO/RAS (Moskvitin et al., GCN 39889, Pankov et al. GCN 39906), SVOM/VT (Xin et al., GCN 39890), GOTO (O’Neill et al. GCN 39891), the NOT (Malesani et al., GCN 39893), Mephisto (Lian et al, GCN 39894), the LCOGT (Shrestha et al. GCN 39896, Kumar et al. GCN 39904, Pérez-Fournon et al. GCN 39912), SVOM/COLIBRI (F-GFT) (Ducoin et al., GCN 39897, 39930), the Liverpool telescope (Perley et al., GCN 39902), the OHP/T193 telescope (Dennefeld et al. GCN 39905) and MASTER (Tarasenkov et al., GCN 39913). We report some of our detections and upper limits (5 sigma) in the following table: --------------------------------------------------------------------------------------------- | Tstart-TGRB (hr) | Exposure | Mag | UL (5σ) | Filter | Telescope | --------------------------------------------------------------------------------------------- | 1.62 | 180s | 16.87 ± 0.06 | | Rc (Vega) | T-BRO | | 1.67 | 180s | 17.48 ± 0.10 | | V (Vega) | T-BRO | | 3.29 | 10x60s | 18.98 ± 0.09 | | V (Vega) | ODK16 f/6.8 | | 3.52 | 180s | | 17.8 | V (Vega) | Quatro F4 | | 3.56 | 2x300s | 19.78 ± 0.11 | | g’ (AB) | ODK16 f/6.8 | | 3.58 | 180s | | 17.6 | R (Vega) | Quatro F4 | | 3.81 | 3x300s | 18.93 ± 0.17 | | r’ (AB) | ODK16 f/6.8 | | 4.24 |10x180s | 19.73 ± 0.21 | | V (Vega) | T-BRO | | 6.49 |10x180s | | 20.6 | g’ (AB) | T180 | | 6.51 |15x180s | 20.16 ± 0.36 | | Rc (Vega) | T-BRO | | 6.74 |10x180s | 19.87 ± 0.24 | | r’ (AB) | T180 | | 29.07 |100x40s | | 20.3 | r’ (AB) | Newton T200 | | 76.42 | 59x80s | | 20.5 | V (Vega) | Telescope Live T200 | --------------------------------------------------------------------------------------------- All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022, 2025). Images obtained in Johnson Cousin filters were calibrated using the Gaia DR3 Synphot catalog. Images obtained with sloan filters were calibrated using the PanSTARRS DR1 catalog. We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023). GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/). View this GCN Circular online at https://gcn.nasa.gov/circulars/40006. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38025] GCN Announcement: Circulars over Kafka Event Name Backfill
by GCN Announcements 01 Apr '25

01 Apr '25

In preparation for new search and sort features in the GCN Circulars archive, on April 7, 2025 the GCN team will be backfilling the automatically assigned event name (e.g. "eventId": "GRB 250331C") derived from each GCN Circular subject. Event names have been included in all JSON versions of Circulars starting with GCN Circular 37912. The backfill of all prior Circulars will result in the following behavior that may impact some users: - The entire archive of ~40k Circulars will be distributed over Kafka with the new event names. - Revised Circulars will not be redistributed over email. For more details on this new feature and an archive of GCN news and announcements, see https://gcn.nasa.gov/news. For questions, issues, or bug reports, please contact us via: - Contact form: https://gcn.nasa.gov/contact - GitHub issue tracker: https://github.com/nasa-gcn/gcn.nasa.gov/issues --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38024] GRB250331D: AbAO optical observations
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40005 SUBJECT: GRB250331D: AbAO optical observations DATE: 25/04/01 14:15:27 GMT FROM: Alexei Pozanenko at IKI, Moscow <grb.alex(a)gmail.com> N. Pankov (HSE, IKI), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI) report on behalf of IKI GRB-FuN: We observed the entire localisation region of BAT-GUANO/Swift of GRB250331D (Ronchini et al., GCN 39979), initially detected by GBM/Fermi (Fermi GBM team, GCN 39961) with AS-32 telescope of AbAO starting on 2025-03-31 (UT) 18:56:37. We report the results of optical transient searches in five XRT/Swift localisations reported in https://www.swift.ac.uk/ToO_GRBs/00021825/ and (Melandri et al., GCN 39998). Details of the preliminary photometry of the stacked image and the sources detected so far are given below. Date UT start t-T0 Filter Exp. UL(3sigma) Telescope (mid, d) (s) 2025-03-31 18:56:37 0.56447 R 61x60 20.8 AS-32 XRT #1 ------ RA = 48.26026d Dec = 62.30756d Err90 = 5.1" Inside the XRT error circle the single source is detected: RA = 48.25957d +/- 0.05" Dec = 62.30756 +/- 0.02" R(AbAO) = 13.24 +/- 0.05 USNO-B1.0 R2 = 13.39 XRT #2 ------ RA = 48.65718d Dec = 62.28326d Err90 = 3.5" Inside the XRT error circle the single source is detected: RA = 48.66142d +/- 0.14" Dec = 62.28324d +/- 0.07" R(AbAO) = 18.72 +/- 0.07 USNO-B1.0 R2 = 18.97 XRT #3 ------ RA = 48.86152d Dec = 62.34017d Err90 = 7.0" Inside the XRT error circle the single source is detected: RA = 48.85897d +/- 0.12" Dec = 48.85897d +/- 0.06" R(AbAO) = 18.64 +/- 0.07 USNO-B1.0 R2 = 18.93 XRT #4 ------ RA = 48.77053d Dec = 62.37337d Err90 = 5.9" Inside the XRT error circle the single source is detected: RA = 48.76831d +/- 0.3" Dec = 62.37292d +/- 0.3" R(AbAO) = 19.68 +/- 0.26 USNO-B1.0 R2 = 19.94 XRT #5 ------ RA = 48.3703896d Dec = 62.10607d Err90 = 6.9" Inside the XRT error circle the single source is detected: RA = 48.37039d +/- 0.3" Dec = 62.10664d +/- 0.3" R(AbAO) ~ 21.0 PS1 r = 21.17 +/- 0.15, i = 20.21 +/- 0.06 We did not identify any variable sources in any of the XRT localisations ( https://www.swift.ac.uk/ToO_GRBs/00021825/). View this GCN Circular online at https://gcn.nasa.gov/circulars/40005. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38023] GRB 250331D: Fermi GBM observation
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40004 SUBJECT: GRB 250331D: Fermi GBM observation DATE: 25/04/01 13:33:45 GMT FROM: Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi(a)ba.infn.it> E. Bissaldi (Politecnico and INFN Bari), C. Meegan (UAH) and A. Holzmann Airasca (Univ. Trento and INFN Bari) report on behalf of the Fermi GBM Team: "At 05:49:17.01 UT on 31 March 2025, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 250331D (trigger 765092962 / 250331243), which was also detected by the Swift/BAT-GUANO (Ronchini et al. 2025, GCN 39979). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 27 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 9 s (50-300 keV). The time-averaged spectrum from T0-2.5 s to T0+6.4 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -1.12 +/- 0.27 and the cutoff energy, parameterized as Epeak, is 91 +/- 20 keV. The event fluence (10-1000 keV) in this time interval is (6.1 +/- 0.8)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.64 s in the 10-1000 keV band is 2.2 +/- 0.2 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/40004. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38022] GRB 250331C: Swift/UVOT Upper Limits
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40003 SUBJECT: GRB 250331C: Swift/UVOT Upper Limits DATE: 25/04/01 13:06:09 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) and S. B. Cenko (GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250331C 140 s after the BAT trigger (Cenko et al., GCN Circ. 39959). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ. 39977) 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 white_FC 140 289 147 >21.1 u_FC 297 547 246 >19.9 white 140 1717 411 >22.3 v 628 1767 136 >19.1 b 553 1863 133 >20.1 u 297 1841 363 >20.1 w1 676 1817 136 >19.1 m2 652 1792 136 >19.8 w2 603 1743 136 >20.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.921 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/40003. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38021] GRB 250331B: Swift/UVOT Upper Limits
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40002 SUBJECT: GRB 250331B: Swift/UVOT Upper Limits DATE: 25/04/01 13:04:29 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) and S. B. Cenko (GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250331B 317 s after the BAT trigger (Cenko et al., GCN Circ. 39958). No optical afterglow consistent with the XRT position (Osborne et al., GCN Circ. 39974) 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 white_FC 317 467 147 >19.5 white 317 1020 334 >19.9 v 474 1070 78 >18.3 b 572 764 39 >18.3 u 547 1144 58 >18.6 w1 523 1120 58 >18.0 m2 670 690 19 >17.7 w2 621 1046 58 >18.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.979 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/40002. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38020] GRB 250328A: AbAO AS-32 Optical Observations
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40001 SUBJECT: GRB 250328A: AbAO AS-32 Optical Observations DATE: 25/04/01 13:02:02 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of GRB 250328A (Brunet et. al, GCN 39910; Osborne et. al, GCN 39967) with the 0.7-meter AS-32 telescope of the Abastumani Astrophysical Observatory (AbAO). The observations started on (UT) 2025-03-28 20:21:40, i.e. about 0.17 days since trigger. The series of frames in the R-filter was obtained. We marginally detect the optical afterglow (Schneider et. al, GCN 39919; Schneider et. al, GCN 39920; Li et. al, GCN 39923; Li et. al, GCN 39936; Kumar et. al, GCN 39946; Klingler et. al, GCN 39968) in the stacked image. The preliminary photometry is as follows: Date UT start t-T0 Exp. Filter OT Err UL (mid, days) (s) (3sigma) 2025-03-28 20:21:40 0.17064 82*60 R 22.2 S/N=1.7 21.6 The photometry is based on nearby stars of USNO-B1.0 and has not been corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40001. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38019] GRB 250219A: NOT candidate host galaxy detection
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40000 SUBJECT: GRB 250219A: NOT candidate host galaxy detection DATE: 25/04/01 09:28:18 GMT FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani(a)astro.ru.nl> Daniele B. Malesani (DAWN/NBI and Radboud Univ.), Benjamin Schneider (LAM), Gregory Corcoran (UCD), A. Martin-Carrillo (UCD), and Nikko Pyykkinen (NOT and Turku) report on behalf of a larger collaboration: We observed the field of GRB 250219A (Daigne et al., GCN 39376) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC imager. Observations were carried out with the r-band filter and started on 2025 March 26 at 02:18 UT (34.4 days after the GRB), for a total of 50 min on source. Seeing and Moon conditions were favorable. Consistent with the position of the optical afterglow (Xin et al., GCN 39380; Magnani et al., GCN 39382; Fu et al., GCN 39383), we detect a faint object with AB magnitude r = 25.2 +- 0.3, calibrated against nearby objects from Pan-STARRS. While we note a slight offset (~0.9") compared to the afterglow position (Fu et al., GCN 39383), we suggest the above object to be a candidate host galaxy of GRB 250219A. We thank Liping Xin, Francis Fortin and Susanna Vergani for helpful discussion. View this GCN Circular online at https://gcn.nasa.gov/circulars/40000. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38018] GRB 250322B: GRBAlpha detection
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 39999 SUBJECT: GRB 250322B: GRBAlpha detection DATE: 25/04/01 09:27:19 GMT FROM: Martin Kolář at Masaryk University <mkolar(a)physics.muni.cz> M. Kolar, M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, L. Szakszonova, M. Duriskova, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration. The long-duration GRB 250322B (AstroSat/CZTI: GCN Circular 39848, NuSTAR: GCN Circular 39857) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui.adsabs.harvard.edu/abs/2023A%26A...677A..40P/abstract). The detection was confirmed at the peak time 2025-03-22 20:08:19 UTC . The T90 duration measured by GRBAlpha is 77.5 s and the overall significance during T90 reaches 132 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB250322B_GCN.pdf All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. View this GCN Circular online at https://gcn.nasa.gov/circulars/39999. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38017] GRB 250331D: Swift-XRT observations
by GCN Circulars 01 Apr '25

01 Apr '25

TITLE: GCN CIRCULAR NUMBER: 39998 SUBJECT: GRB 250331D: Swift-XRT observations DATE: 25/04/01 08:59:42 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Swift/BAT-detected burst GRB 250331D, collecting 5.3 ks of Photon Counting (PC) mode data between T0+45.2 ks and T0+68.1 ks. Two uncatalogued X-ray sources have been detected within the estimated 3-sigma Swift/BAT error region (493 arcsec), however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below: Source 2: RA (J2000.0): 48.6572 = 03:14:37.72 Dec (J2000.0): +62.2833 = +62:16:59.7 Error: 3.5 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: (7.4 [+1.6, -1.4])e-3 ct s^-1 Distance: 235 arcsec from Swift/BAT position. Flux: (3.18 [+0.67, -0.61])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 4: RA (J2000.0): 48.7705 = 03:15:4.93 Dec (J2000.0): +62.3734 = +62:22:24.1 Error: 5.9 arcsec (radius, 90% conf.) Count-rate: (1.77 [+0.95, -0.72])e-3 ct s^-1 Distance: 476 arcsec from Swift/BAT position. Flux: (1.19 [+0.64, -0.49])e-10 erg cm^-2 s^-1 (observed, 0.3-10 keV) A catalogued source was also detected within the estimated 3-sigma Swift/BAT error region (493 arcsec). Two uncatalogued sources were also detected too far from the GRB position to be likely afterglow candidates. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00021825. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39998. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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