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

[vsnet-grb-info 38827] Fermi Gamma-ray Burst Monitor trigger 772058337/250619860 is not a GRB
by GCN Circulars 19 Jun '25

19 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40786 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 772058337/250619860 is not a GRB DATE: 25/06/19 21:58:33 GMT FROM: eliza.neights(a)gmail.com E. Neights (GWU, NASA GSFC) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 772058337/250619860 at 20:38:52.44 UT on 19 June 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/40786. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38826] GRB 250615A: Kilonova-Catcher optical upper limits
by GCN Circulars 19 Jun '25

19 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40785 SUBJECT: GRB 250615A: Kilonova-Catcher optical upper limits DATE: 25/06/19 21:45:50 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro(a)hotmail.com> D. Turpin (CEA-Saclay/Irfu), R. Hellot, M. Freeberg (KNC), C. Andrade(UMN), M. Pillas (ULiege), M. Tanasan (NARIT), S. Antier (OCA/IJCLAB) on behalf of the GRANDMA/Kilonova-Catcher collaboration: We observed the field of GRB 250615A (Dichiara et al., GCN 40736) detected by Swift/BAT with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with the TEC160FL telescope operated by M. Freeberg and a CDK17 telescope located at AITP San Pedro Chile Observatory operated by R. Hellot. Our observations started at TGRB+7.6hr. In our stacked frames, subtracted from the PanSTARRS DR2 template image, we do not detect any optical counterpart inside the Swift/XRT refined position (Goad et al., GCN 40739). We report our follow-up results in the table below: +---------------+-------------+---------+---------------------+--------------+ | Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument | +===============+=============+=========+=====================+==============+ | 7.9 | 6 x 300s | r (AB) | 20.1 (U.L., 5sigma) | TEC160FL | | 8.1 | 11 x 300s | g (AB) | 20.8 (U.L., 5sigma) | CDK17-AITP | | 8.5 | 6 x 300s | g (AB) | 20.4 (U.L., 5sigma) | TEC160FL | | 9.0 | 6 x 300s | i (AB) | 19.2 (U.L., 5sigma) | TEC160FL | | 9.6 | 11 x 300s | r (AB) | 20.2 (U.L., 5sigma) | CDK17-AITP | +---------------+-------------+---------+---------------------+--------------+ All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained with the sloan images 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/40785. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38825] GRB 250619A: Fermi GBM Final Real-time Localization
by GCN Circulars 19 Jun '25

19 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40784 SUBJECT: GRB 250619A: Fermi GBM Final Real-time Localization DATE: 25/06/19 15:25:10 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 15:14:36 UT on 19 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250619A (trigger 772038881.892868 / 250619635). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 35.1, Dec = 27.0 (J2000 degrees, equivalent to J2000 02h 20m, 27d 00'), with a statistical uncertainty of 3.9 degrees. The angle from the Fermi LAT boresight is 40.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250619635/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250619635/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250619635/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40784. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38824] GRB 250617B: Assy AZT-20 Optical Observations
by GCN Circulars 19 Jun '25

19 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40783 SUBJECT: GRB 250617B: Assy AZT-20 Optical Observations DATE: 25/06/19 14:26:12 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), V. Kim (FAI), A. Pozanenko (IKI), M. Krugov (FAI) report on behalf of IKI-GRB-FuN: We performed optical observations of the field of GRB 250617B (Page et. al, GCN 40760; The Fermi GBM team, GCN 40763) using the 1.5-meter AZT-20 of the Assy-Turgen Observatory. The observations were conducted starting on 2025-06-18 at 18:02:27 UT, i.e. ~0.87 days since the Swift trigger. The series of 53*60 sec images was taken in the r'-filter. We detect the optical afterglow (Page et. al, GCN 40760, Moskvitin et. al, GCN 40761, Jelinek et. al, GCN 40762; Kumar et. al, GCN 40768; Lipunov et. al, GCN 40769; Grossan et. al, GCN 40771; Ma et. al, GCN 40772; Schneider et. al, GCN 40774; Antier et. al, GCN 40775; Corcoran et. al, GCN 40776; Turpin et. al, GCN 40777; Siegel & Page, GCN 40778). The preliminary photometry is given below: Date UT start t-T0 Exp. Filter OT Err. UL (mid, days) (n*s) (3sigma) 2025-06-18 18:02:27 0.87577 53*60 r' 21.58 0.04 22.5 The photometry has calibrated using nearby stars from PS1 (at the same coordinates as USNO-B1.0 stars given in Moskvitin et. al, GCN 40761) and has not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40783. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38823] GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
by GCN Circulars 18 Jun '25

18 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40782 SUBJECT: GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis DATE: 25/06/18 22:43:10 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta(a)nasa.gov> H. A. Krimm (NSF), S. D. Barthelmy (GSFC), R. Gupta (GSFC), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU), M. H. Siegel (PSU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250612A (trigger #1323295) (Siegel, et al., GCN Circ. 40694). The BAT ground-calculated position is RA, Dec = 250.873, -38.948 deg which is RA(J2000) = 16h 43m 29.6s Dec(J2000) = -38d 56' 53.9" with an uncertainty of 4.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 64%. The BAT mask-weighted light curve showed a complex structure with a duration of about 300 sec. T90 (15-350 keV) is 274.17 +- 66.54 sec (estimated error including systematics). The time-averaged spectrum from T-0.58 to T+291.52 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.55 +- 0.43. The fluence in the 15-150 keV band is 1.0 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+0.62 sec in the 15-150 keV band is 0.9 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. Given the BAT detection at a Galactic latitude of 4.6 deg and the absence of a detected X-ray afterglow in XRT observations ~ 17 hours post-trigger, a Galactic origin of this source remains plausible. If confirmed as a new Galactic transient, it would be designated Swift J1643.6−3854. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1323295 View this GCN Circular online at https://gcn.nasa.gov/circulars/40782. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38822] Fermi GRB 250617A: Global MASTER-Net observations report
by GCN Circulars 18 Jun '25

18 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40781 SUBJECT: Fermi GRB 250617A: Global MASTER-Net observations report DATE: 25/06/18 22:15:43 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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 250617A ( Fermi GBM team, GCN 40758) errorbox 1 days 17814 sec after notice time and 1 days 17823 sec after trigger time at 2025-06-18 21:06:16 UT, with upper limit up to 17.7 mag. The observations began at zenith distance = 66 deg. The sun altitude is -23.6 deg. The galactic latitude b = -25 deg., longitude l = 107 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2905762 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 104253 | 2025-06-18 21:06:16 | MASTER-Kislovodsk | (23h 40m 51.75s , +35d 31m 02.8s) | C | 60 | 17.7 | 104540 | 2025-06-18 21:11:02 | MASTER-Kislovodsk | (23h 27m 52.38s , +37d 23m 28.9s) | C | 60 | 16.0 | 104624 | 2025-06-18 21:12:26 | MASTER-Kislovodsk | (23h 37m 52.75s , +37d 24m 33.4s) | C | 60 | 16.3 | 104845 | 2025-06-18 21:16:08 | MASTER-Kislovodsk | (23h 46m 54.05s , +37d 24m 18.0s) | C | 60 | 17.3 | 104928 | 2025-06-18 21:17:31 | MASTER-Kislovodsk | (23h 57m 02.84s , +37d 22m 47.1s) | C | 60 | 16.6 | 105010 | 2025-06-18 21:18:53 | MASTER-Kislovodsk | (23h 40m 51.77s , +35d 28m 47.9s) | C | 60 | 17.1 | 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/40781. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38821] GRB 250615A/EP250615a: FTW optical and NIR observations
by GCN Circulars 18 Jun '25

18 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40780 SUBJECT: GRB 250615A/EP250615a: FTW optical and NIR observations DATE: 25/06/18 19:24:32 GMT FROM: Malte Busmann at Ludwig-Maximilians-Universität München <m.busmann(a)physik.lmu.de> Malte Busmann (LMU), Brendan O’Connor (Carnegie Mellon U.), Daniel Gruen (LMU), and Antonella Palmese (Carnegie Mellon U.) report: We observed the improved localization (Evans et al., GCN 40737; Goad et al., GCN 40739) of GRB 250615A/EP250615a (Dichiara et al., GCN 40736; Yang et al., GCN 40743; Burrows et al., GCN 40745; Tembhurnikar et al., GCN 40752; Frederiks et al., GCN 40753; Barthelmy et al. GCN 40765) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i and J band simultaneously for 20 x 180 s starting at 2025-06-17T21:29:37 UT (1.96 days after the trigger). We detect no new source in the 90% Swift/XRT localization (Evans et al., GCN 40737; Goad et al., GCN 40739) down to a 3-sigma depth of r > 23.9 mag i > 23.3 mag J > 21.8 mag. These upper limits are consistent with the previous observations by Kuin et al. (GCN 40747), Becerra et al. (GCN 40748), Magnani et al. (GCN 40749), and Calapai & Giorgio (GCN 40759). The r and i band magnitudes are calibrated against the PS1 catalog and the J band is calibrated with the 2MASS Catalog. All magnitudes are provided in the AB system and are not corrected for the significant Galactic extinction at this location. We thank Michael Schmidt from the Wendelstein Observatory staff for obtaining these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/40780. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38820] sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
by GCN Circulars 18 Jun '25

18 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40779 SUBJECT: sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations DATE: 25/06/18 14:55:00 GMT FROM: Christophe Adami at LAM <christophe.adami(a)lam.fr> C. Adami (LAM/Pytheas/AMU), B. Schneider (LAM), S. Basa (LAM/OHP/Pytheas/AMU), E. Le Floc'h (CEA/Irfu), M. Dennefeld (IAP/Sorbonne U.), J. L. Atteia (IRAP), J. Rodriguez (CEA), F. Cangemi (APC), A. Coleiro (APC), Y. Degot-Longui (Pytheas/OHP), J. Balcaen (Pytheas/OHP), report on behalf of a larger collaboration: We observed the field of the SVOM sb25061218 X-ray transient (Rodriguez et al., GCN 40712) using the T120cm and the T193cm equipped with the MISTRAL spectro-imager at Observatoire de Haute-Provence (France). Our T120 observations consisted of multiple epochs from 2025-06-12T22:07 to 2025-06-13T00:46 UT (from 1.52 to 4.17 hr after the trigger) in r-band and covered both uncatalogued X-ray sources seen with Swift/XRT (Evans et al. GCN 40721). We examined the sources visible at the XRT #1 and #2 positions and noted a rebrightening of ~0.3 mag of the SIMBAD object [VV2006] J131446.6+544804 compared to SDSS (r = 18.66 +/- 0.02) and PanStarrs (r = 18.65 +/- 0.01) surveys, possibly associated with the XRT source #1. The magnitudes derived for that source are: date-obs (UT) | exposure time (min) | band, mag (AB) | mag err 2025-06-12T22:07 | 12min | r | 18.33 | 0.02 2025-06-12T22:36 | 12min | r | 18.29 | 0.04 2025-06-12T23:54 | 4min | r | 18.35 | 0.03 2025-06-13T00:46 | 8min | r | 18.36 | 0.03 On 2025-06-13 starting at 20:27 UT (23.85 hr after the trigger), we re-observed the object [VV2006] J131446.6+544804 with the spectro-imager MISTRAL. We obtained 1 minute of observation in r-band and measured a magnitude of r = 18.37 +/- 0.07, consistent with the T120 measurements on 2025-06-12. We also obtained 1 hour of spectroscopic observations using the MISTRAL blue mode with a spectral resolution of ~700 under moderately good conditions. When compared to the SDSS public spectrum, a preliminary analysis of the spectrum shows a flux increase of the Fe II complex between ~6600 AA and ~7000 AA. This increase is roughly consistent with the r-band magnitude variation observed by the T120 and MISTRAL. Our observations suggest that the Swift/XRT source #1 is the X-ray counterpart to [VV2006] J131446.6+544804 source, a known QSO at z~ 0.49. The X-ray detection of this source is the first reported to our knowledge and may indicate that the SVOM trigger is also associated with this event. This object being radio-quiet (2.9 mJy at 1.4GHz, NVSS) without typical lines of TDEs, and the observed r-band magnitudes being nearly constant after the initial increase suggest a likely association with an accretion event onto the central black hole of this QSO and would disfavor a GRB nature of this event. We encourage further observations of [VV2006] J131446.6+544804. We acknowledge the excellent support from Observatoire de Haute-Provence and in particular the students and professors from the summer camp OHP 2025 (Institut Origines) and the SOPHIE observer, Xavier Delfosse. View this GCN Circular online at https://gcn.nasa.gov/circulars/40779. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38819] GRB 250617B: Swift/UVOT Detection
by GCN Circulars 18 Jun '25

18 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40778 SUBJECT: GRB 250617B: Swift/UVOT Detection DATE: 25/06/18 13:09:34 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250617B 797 s after the BAT trigger (Page et al., GCN Circ. 40760). A source consistent with the XRT position (Osborne et al., GCN Circ 40767) is detected in the initial UVOT exposures. The lack of detection in the uvw2 and uvm2 filters would be consistent with the redshift reported by Corcoran et al. (GCN Circ. 40776). The preliminary UVOT position is: RA (J2000) = 22:11:35.25 = 332.89686 (deg.) Dec (J2000) = +32:43:57.1 = 32.73253 (deg.) with an estimated uncertainty of 0.44 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 797 946 147 18.18 +/- 0.05 v 1130 2528 172 18.72 +/- 0.19 b 1229 1596 58 18.91 +/- 0.18 u 1204 1397 39 18.10 +/- 0.19 w1 1179 2408 156 19.32 +/- 0.28 m2 1155 2384 117 >18.3 w2 1106 2507 175 >19.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.087 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/40778. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38818] GRB 250617B: Kilonova-Catcher optical afterglow detection
by GCN Circulars 18 Jun '25

18 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40777 SUBJECT: GRB 250617B: Kilonova-Catcher optical afterglow detection DATE: 25/06/18 11:19:22 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro(a)hotmail.com> D. Turpin (CEA-Saclay/Irfu), M. Freeberg (KNC), C. Andrade(UMN), M. Pillas (ULiege), M. Tanasan (NARIT), S. Antier (OCA/IJCLAB) on behalf of the GRANDMA/Kilonova-Catcher collaboration: We observed the field of GRB 250617B (Page et al., GCN 40760) detected by Swift/BAT with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with the TEC160FL telescope operated by M. Freeberg starting from T_GRB+10hr. In our stacked frames, subtracted from the PanSTARRS DR2 template image, we marginally detect the optical afterglow at the position reported by Swift/UVOT (Page et al., GCN 40760), SAO RAS (Moskvitin et al., GCN 40761), Ondrejov D50 (Jelinek et al., GCN 40762), NUTTelA-TAO (Grossan et al., GCN 40771), SVOM/VT (Mat et al., GCN 40772), NOT (Schneider et al., GCN 40774), COLIBRÍ (Antier et al., GCN 40775) and VLT/X-shooter (Corcoran et al., GCN 40776) We report our follow-up results in the table below: +---------------+-------------+--------------+----------------+--------------+ | Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument | +===============+=============+==============+================+==============+ | 10.8 | 18 x 300s | r (AB) | 20.85 +/- 0.29 | TEC160FL | +---------------+-------------+--------------+----------------+--------------+ All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained with the sloan images 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/40777. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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