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[vsnet-grb-info 41223] GRB 251214B: Mondy optical upper limit
by GCN Circulars 16 Dec '25

16 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43141 SUBJECT: GRB 251214B: Mondy optical upper limit DATE: 25/12/16 13:49:15 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. A. Volnova (IKI), E. Klunko (ISTP), A. S. Pozanenko (IKI), N. S. Pankov (HSE, IKI) report on behalf of IKI-GRB-FuN: We observed the field of the long GRB 251214B detected by Fermi (Fermi team, GCN 43088), Swift (Eyles-Ferris et al., GCN 43089; Evans et al., GCN 43098; Kuin and Eyles-Ferris, GCN 43105; Burrows et al., GCN 43112; Laha et al., GCN 43129), and GECAM-B (Luo et al., GCN 43113) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) taking several 120-second expositions in R-band starting on Dec.15 UT 11:36:28. In the stacked image we do not detect the optical counterpart reported previously (Eyles-Ferris et al., GCN 43089; Kang et al., GCN 43093; Gress et al., GCN 43095; Fu et al., GCN 43097; Gupta et al., GCN 43100; Watson et al., GCN 43103; Kuin and Eyles-Ferris, GCN 43105; Pérez-Fournon et al., GCN 43123; Volnova et al., GCN 43124; de Ugarte Postigo et al., GCN 43131; Pankov et al., GCN 43132; Lin et al., GCN 43134). Preliminary photometry and observational details are the following: Date UT start t-T0 Exp. Filter Obj. Err. UL Site/Telescope (mid,days) (n*s) (3sigma) 2025-12-15 11:36:28 1.12792 30*120 R n/d n/d 22.6 Mondy/AZT-33IK The photometry is based on several nearby stars from the USNO-B1 catalogue (R2 magnitudes) and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43141. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41222] GRB 251215A: COLIBRÍ optical upper limit
by GCN Circulars 16 Dec '25

16 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43140 SUBJECT: GRB 251215A: COLIBRÍ optical upper limit DATE: 25/12/16 12:53:38 GMT FROM: Stephane Basa at UAR Pytheas/OHP, LAM <stephane.basa(a)lam.fr> Stéphane Basa (UAR Pytheas), Leonardo García García (UNAM), Benjamin Schneider (LAM), Noémie Globus (UNAM), Jean-Luc Atteia (IRAP), William H. Lee (UNAM), Alan M. Watson (UNAM), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Ramandeep Gill (UNAM), Enrique Moreno Méndez (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Nikos Mandarakas (LAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), and Antonio de Ugarte Postigo (LAM). We imaged the field of GRB 251215A detected by Fermi (Fermi GBM team, GCN Circ. 43104) and confirmed by Swift/BAT-GUANO (Ronchini et al., GCN Circ. 43114) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2025-12-15 at 11:27:37.35 to 12:06:41.62 UTC (from 7.10 to 7.76 hr after the Fermi trigger) and obtained 31 minutes of simultaneous exposure in the r and z filters. Observations were obtained at a relatively high airmass (~3.0), and we also noted that the Galactic extinction is significant at the Swift/BAT-GUANO localization (Av= ~2.8). The data were reduced, coadded and analyzed with the COLIBRÍ pipeline. The photometry was calibrated using nearby stars from the SkyMapper-DR4 catalog, is in the AB system, and was not corrected for Galactic extinction. In the stacked image, we do not detect any new source associated with the candidates reported by Swift-XRT (Osborne et al., GCN Circ. 43137) down to the following 5-sigma limit: r > 21.8 z > 20.5 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/43140. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41221] GRB 251216A: Fermi GBM Final Real-time Localization
by GCN Circulars 16 Dec '25

16 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43139 SUBJECT: GRB 251216A: Fermi GBM Final Real-time Localization DATE: 25/12/16 09:48:49 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 09:38:09 UT on 16 Dec 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251216A (trigger 787570694.65431 / 251216401). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 290.9, Dec = 52.0 (J2000 degrees, equivalent to J2000 19h 23m, 52d 00'), with a statistical uncertainty of 9.3 degrees. The angle from the Fermi LAT boresight is 42.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251216401/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251216401/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251216401/… View this GCN Circular online at https://gcn.nasa.gov/circulars/43139. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41220] EP251214b: KAIT optical upper limit
by GCN Circulars 16 Dec '25

16 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43138 SUBJECT: EP251214b: KAIT optical upper limit DATE: 25/12/16 08:38:39 GMT FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu> WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, observed the field of EP251214b (Jiang et al., GCN 43125) starting at 08:17, Dec 14 UT, about 0.95 hours after the trigger. A set of 29x60s and again 40x60s clear (roughly R) filter images were obtained. In our coadd images, we did not detect any new source within the EP-WXT error circle (Jiang et al., GCN 43125) down to limiting mag of 20.8 and 21.5 mag (Vega) at a mid-time of 1.23 and 3.12 hours after the trigger. Our result is consistent with the upper limit reported by other groups (Eyles-Ferris et al., GCN 43117; Lipunov et al., GCN 43127). View this GCN Circular online at https://gcn.nasa.gov/circulars/43138. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41219] GRB 251215A: Swift-XRT observations
by GCN Circulars 16 Dec '25

16 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43137 SUBJECT: GRB 251215A: Swift-XRT observations DATE: 25/12/16 08:06:33 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> 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), S. Lanava (PSU), S. Dichiara (PSU), J.A. Kennea (PSU) 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 251215A, collecting 5.2 ks of Photon Counting (PC) mode data between T0+32.0 ks and T0+49.6 ks. Four uncatalogued X-ray sources have been detected within the estimated 3-sigma Swift/BAT error region (493 arcsec), however none of them is above historical upper limits, 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): 122.5523 = 08h 10m 12.54s Dec (J2000.0): -36.6697 = -36d 40' 10.8" Error: 3.9 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: (9.7 [+1.8, -1.7])e-3 ct s^-1 Distance: 383 arcsec from Swift/BAT position. Flux: (4.47 [+0.81, -0.77])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 5: RA (J2000.0): 122.6189 = 08h 10m 28.54s Dec (J2000.0): -36.7427 = -36d 44' 33.6" Error: 5.7 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: (5.0 [+1.3, -1.2])e-3 ct s^-1 Distance: 97 arcsec from Swift/BAT position. Flux: (1.96 [+0.50, -0.47])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 6: RA (J2000.0): 122.6954 = 08h 10m 46.90s Dec (J2000.0): -36.6198 = -36d 37' 11.5" Error: 7.1 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: (3.44 [+1.20, -0.99])e-3 ct s^-1 Distance: 448 arcsec from Swift/BAT position. Flux: (2.87 [+1.00, -0.83])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 8: RA (J2000.0): 122.6662 = 08h 10m 39.88s Dec (J2000.0): -36.6483 = -36d 38' 53.8" Error: 5.9 arcsec (radius, 90% conf.) Count-rate: (1.81 [+0.92, -0.72])e-3 ct s^-1 Distance: 330 arcsec from Swift/BAT position. Flux: (3.7 [+1.9, -1.5])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/00021894. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43137. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41218] Fermi GRB 251215A: Global MASTER-Net observations report
by GCN Circulars 16 Dec '25

16 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43136 SUBJECT: Fermi GRB 251215A: Global MASTER-Net observations report DATE: 25/12/16 07:30:37 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 [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 251215A ( Fermi GBM team, GCN 43104) errorbox 708 sec after notice time and 729 sec after trigger time at 2025-12-15 04:33:30 UT, with upper limit up to 20.3 mag. The observations began at zenith distance = 25 deg. The sun altitude is -35.7 deg. The galactic latitude b = -12 deg., longitude l = 256 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3071404 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 759 | 2025-12-15 04:33:30 | MASTER-OAFA | (07h 21m 38.63s , -44d 11m 53.3s) | C | 60 | 19.8 | 836 | 2025-12-15 04:34:47 | MASTER-OAFA | (07h 32m 44.70s , -44d 12m 40.8s) | C | 60 | 19.7 | 1278 | 2025-12-15 04:42:09 | MASTER-OAFA | (07h 21m 33.82s , -44d 13m 28.4s) | C | 60 | 20.1 | 1356 | 2025-12-15 04:43:27 | MASTER-OAFA | (07h 32m 50.29s , -44d 13m 23.2s) | C | 60 | 20.0 | 1537 | 2025-12-15 04:46:28 | MASTER-OAFA | (07h 21m 36.90s , -44d 13m 08.5s) | C | 60 | 20.2 | 1616 | 2025-12-15 04:47:47 | MASTER-OAFA | (07h 28m 30.24s , -42d 18m 18.6s) | C | 60 | 19.8 | 1692 | 2025-12-15 04:49:03 | MASTER-OAFA | (07h 39m 20.70s , -42d 17m 18.4s) | C | 60 | 19.5 | 1768 | 2025-12-15 04:50:19 | MASTER-OAFA | (07h 28m 37.49s , -42d 18m 11.5s) | C | 60 | 19.8 | 1844 | 2025-12-15 04:51:35 | MASTER-OAFA | (07h 39m 20.66s , -42d 19m 12.0s) | C | 60 | 19.5 | 1920 | 2025-12-15 04:52:51 | MASTER-OAFA | (07h 28m 37.47s , -42d 18m 57.2s) | C | 60 | 19.8 | 1998 | 2025-12-15 04:54:09 | MASTER-OAFA | (07h 14m 43.71s , -46d 06m 35.4s) | C | 60 | 20.3 | 2073 | 2025-12-15 04:55:24 | MASTER-OAFA | (07h 26m 20.85s , -46d 05m 09.8s) | C | 60 | 20.3 | 2149 | 2025-12-15 04:56:40 | MASTER-OAFA | (07h 14m 41.57s , -46d 05m 53.1s) | C | 60 | 20.3 | 2225 | 2025-12-15 04:57:56 | MASTER-OAFA | (07h 26m 14.02s , -46d 04m 51.5s) | C | 60 | 20.3 | 4916 | 2025-12-15 05:42:47 | MASTER-OAFA | (07h 32m 47.05s , -44d 22m 53.9s) | C | 60 | 20.1 | 4992 | 2025-12-15 05:44:03 | MASTER-OAFA | (07h 32m 47.23s , -44d 24m 00.4s) | C | 60 | 20.1 | 5071 | 2025-12-15 05:45:22 | MASTER-OAFA | (07h 32m 50.60s , -44d 22m 25.2s) | C | 60 | 20.1 | 5147 | 2025-12-15 05:46:38 | MASTER-OAFA | (07h 21m 35.26s , -44d 22m 27.4s) | C | 60 | 20.3 | 5224 | 2025-12-15 05:47:55 | MASTER-OAFA | (07h 21m 40.10s , -44d 23m 25.8s) | C | 60 | 20.2 | 5301 | 2025-12-15 05:49:12 | MASTER-OAFA | (07h 21m 35.65s , -44d 24m 24.1s) | C | 60 | 20.2 | 5377 | 2025-12-15 05:50:28 | MASTER-OAFA | (07h 39m 26.43s , -42d 29m 44.8s) | C | 60 | 19.6 | 5454 | 2025-12-15 05:51:45 | MASTER-OAFA | (07h 39m 23.79s , -42d 28m 14.2s) | C | 60 | 19.6 | 5530 | 2025-12-15 05:53:01 | MASTER-OAFA | (07h 39m 23.97s , -42d 29m 57.9s) | C | 60 | 19.6 | 5607 | 2025-12-15 05:54:18 | MASTER-OAFA | (07h 28m 37.31s , -42d 28m 27.7s) | C | 60 | 19.8 | 5746 | 2025-12-15 05:56:37 | MASTER-OAFA | (07h 28m 32.75s , -42d 29m 10.7s) | C | 60 | 19.8 | 5832 | 2025-12-15 05:58:03 | MASTER-OAFA | (07h 28m 33.73s , -42d 28m 08.7s) | C | 60 | 19.8 | 8125 | 2025-12-15 06:36:16 | MASTER-OAFA | (07h 26m 26.02s , -46d 16m 45.3s) | C | 60 | 20.1 | 8202 | 2025-12-15 06:37:33 | MASTER-OAFA | (07h 26m 23.77s , -46d 15m 06.7s) | C | 60 | 20.1 | 8279 | 2025-12-15 06:38:50 | MASTER-OAFA | (07h 26m 24.09s , -46d 16m 48.0s) | C | 60 | 20.1 | 8360 | 2025-12-15 06:40:11 | MASTER-OAFA | (07h 14m 56.32s , -46d 15m 39.0s) | C | 60 | 20.1 | 8435 | 2025-12-15 06:41:26 | MASTER-OAFA | (07h 14m 50.27s , -46d 16m 09.0s) | C | 60 | 20.1 | 8510 | 2025-12-15 06:42:42 | MASTER-OAFA | (07h 14m 49.98s , -46d 15m 07.3s) | C | 60 | 20.2 | 9066 | 2025-12-15 06:51:57 | MASTER-OAFA | (07h 32m 54.70s , -44d 21m 49.3s) | C | 60 | 20.1 | 9146 | 2025-12-15 06:53:17 | MASTER-OAFA | (07h 32m 54.52s , -44d 20m 48.2s) | C | 60 | 20.1 | 9222 | 2025-12-15 06:54:33 | MASTER-OAFA | (07h 33m 00.52s , -44d 21m 46.6s) | C | 60 | 20.0 | 9300 | 2025-12-15 06:55:51 | MASTER-OAFA | (07h 21m 52.29s , -44d 22m 38.3s) | C | 60 | 20.1 | 9375 | 2025-12-15 06:57:06 | MASTER-OAFA | (07h 21m 49.58s , -44d 21m 12.2s) | C | 60 | 20.1 | 9449 | 2025-12-15 06:58:20 | MASTER-OAFA | (07h 21m 49.84s , -44d 22m 43.6s) | C | 60 | 20.1 | 9528 | 2025-12-15 06:59:39 | MASTER-OAFA | (07h 39m 36.92s , -42d 26m 56.9s) | C | 60 | 19.5 | 9602 | 2025-12-15 07:00:53 | MASTER-OAFA | (07h 39m 31.12s , -42d 27m 41.8s) | C | 60 | 19.5 | 9685 | 2025-12-15 07:02:16 | MASTER-OAFA | (07h 39m 30.42s , -42d 26m 40.3s) | C | 60 | 19.5 | 9761 | 2025-12-15 07:03:32 | MASTER-OAFA | (07h 28m 49.41s , -42d 27m 49.0s) | C | 60 | 19.8 | 9836 | 2025-12-15 07:04:47 | MASTER-OAFA | (07h 28m 43.69s , -42d 28m 48.0s) | C | 60 | 19.8 | 9911 | 2025-12-15 07:06:02 | MASTER-OAFA | (07h 28m 49.61s , -42d 28m 43.1s) | C | 60 | 19.8 | 9989 | 2025-12-15 07:07:20 | MASTER-OAFA | (07h 08m 14.54s , -42d 29m 07.5s) | C | 60 | 20.1 | 10066 | 2025-12-15 07:08:37 | MASTER-OAFA | (07h 19m 05.86s , -42d 26m 59.3s) | C | 60 | 19.9 | 10144 | 2025-12-15 07:09:55 | MASTER-OAFA | (07h 08m 12.74s , -42d 28m 07.0s) | C | 60 | 20.1 | 10220 | 2025-12-15 07:11:11 | MASTER-OAFA | (07h 19m 01.00s , -42d 26m 52.3s) | C | 60 | 19.9 | 10296 | 2025-12-15 07:12:27 | MASTER-OAFA | (07h 08m 18.47s , -42d 28m 04.8s) | C | 60 | 20.0 | 10373 | 2025-12-15 07:13:44 | MASTER-OAFA | (07h 26m 28.67s , -46d 16m 19.5s) | C | 60 | 20.2 | 10447 | 2025-12-15 07:14:58 | MASTER-OAFA | (07h 26m 35.57s , -46d 16m 13.5s) | C | 60 | 20.2 | 10523 | 2025-12-15 07:16:14 | MASTER-OAFA | (07h 26m 32.19s , -46d 14m 44.0s) | C | 60 | 20.2 | 10599 | 2025-12-15 07:17:30 | MASTER-OAFA | (07h 15m 01.09s , -46d 16m 24.8s) | C | 60 | 20.2 | 10676 | 2025-12-15 07:18:47 | MASTER-OAFA | (07h 15m 04.61s , -46d 14m 26.7s) | C | 60 | 20.2 | 10752 | 2025-12-15 07:20:03 | MASTER-OAFA | (07h 14m 57.99s , -46d 15m 24.1s) | C | 60 | 20.2 | 11089 | 2025-12-15 07:25:40 | MASTER-OAFA | (07h 33m 04.54s , -44d 22m 09.2s) | C | 60 | 20.1 | 11164 | 2025-12-15 07:26:55 | MASTER-OAFA | (07h 33m 08.71s , -44d 20m 17.2s) | C | 60 | 20.0 | 11240 | 2025-12-15 07:28:11 | MASTER-OAFA | (07h 33m 02.78s , -44d 21m 08.0s) | C | 60 | 20.1 | 11321 | 2025-12-15 07:29:32 | MASTER-OAFA | (07h 00m 48.69s , -44d 21m 46.6s) | C | 60 | 20.3 | 11397 | 2025-12-15 07:30:48 | MASTER-OAFA | (07h 11m 51.63s , -44d 22m 30.7s) | C | 60 | 20.2 | 11473 | 2025-12-15 07:32:04 | MASTER-OAFA | (07h 00m 48.56s , -44d 22m 37.0s) | C | 60 | 20.2 | 11549 | 2025-12-15 07:33:20 | MASTER-OAFA | (07h 11m 55.05s , -44d 20m 30.4s) | C | 60 | 20.2 | 11626 | 2025-12-15 07:34:37 | MASTER-OAFA | (07h 00m 46.36s , -44d 22m 19.2s) | C | 60 | 20.2 | 11705 | 2025-12-15 07:35:56 | MASTER-OAFA | (07h 39m 43.96s , -42d 26m 19.8s) | C | 60 | 19.5 | 11780 | 2025-12-15 07:37:11 | MASTER-OAFA | (07h 39m 37.07s , -42d 27m 04.2s) | C | 60 | 19.4 | 11855 | 2025-12-15 07:38:26 | MASTER-OAFA | (07h 39m 38.58s , -42d 26m 03.1s) | C | 60 | 19.5 | 11935 | 2025-12-15 07:39:46 | MASTER-OAFA | (07h 30m 51.44s , -48d 09m 35.4s) | C | 60 | 20.1 | 12010 | 2025-12-15 07:41:01 | MASTER-OAFA | (07h 42m 55.59s , -48d 09m 06.7s) | C | 60 | 19.9 | 12087 | 2025-12-15 07:42:18 | MASTER-OAFA | (07h 30m 55.70s , -48d 07m 49.7s) | C | 60 | 20.0 | 12162 | 2025-12-15 07:43:34 | MASTER-OAFA | (07h 42m 52.36s , -48d 09m 05.7s) | C | 60 | 19.9 | 12240 | 2025-12-15 07:44:51 | MASTER-OAFA | (07h 30m 58.65s , -48d 07m 43.9s) | C | 60 | 20.0 | 12318 | 2025-12-15 07:46:09 | MASTER-OAFA | (07h 19m 06.95s , -42d 27m 23.2s) | C | 60 | 19.9 | 12395 | 2025-12-15 07:47:26 | MASTER-OAFA | (07h 19m 08.53s , -42d 26m 22.2s) | C | 60 | 19.9 | 12471 | 2025-12-15 07:48:42 | MASTER-OAFA | (07h 19m 14.47s , -42d 27m 21.2s) | C | 60 | 19.8 | 12546 | 2025-12-15 07:49:57 | MASTER-OAFA | (07h 08m 19.27s , -42d 28m 36.9s) | C | 60 | 20.1 | 12620 | 2025-12-15 07:51:11 | MASTER-OAFA | (07h 08m 26.14s , -42d 28m 23.2s) | C | 60 | 20.0 | 12694 | 2025-12-15 07:52:25 | MASTER-OAFA | (07h 08m 23.68s , -42d 27m 05.0s) | C | 60 | 20.0 | 12771 | 2025-12-15 07:53:42 | MASTER-OAFA | (07h 26m 40.50s , -46d 15m 33.7s) | C | 60 | 20.1 | 12850 | 2025-12-15 07:55:01 | MASTER-OAFA | (07h 26m 43.84s , -46d 13m 52.0s) | C | 60 | 20.1 | 12927 | 2025-12-15 07:56:18 | MASTER-OAFA | (07h 26m 38.20s , -46d 14m 34.8s) | C | 60 | 20.1 | 13003 | 2025-12-15 07:57:35 | MASTER-OAFA | (07h 37m 07.47s , -46d 14m 21.4s) | C | 60 | 20.0 | 13080 | 2025-12-15 07:58:51 | MASTER-OAFA | (07h 48m 32.47s , -46d 15m 08.4s) | C | 60 | 19.8 | 13155 | 2025-12-15 08:00:06 | MASTER-OAFA | (07h 37m 06.85s , -46d 15m 15.8s) | C | 60 | 20.0 | 13238 | 2025-12-15 08:01:29 | MASTER-OAFA | (07h 48m 35.83s , -46d 13m 17.2s) | C | 60 | 19.8 | 13314 | 2025-12-15 08:02:45 | MASTER-OAFA | (07h 37m 05.08s , -46d 15m 00.9s) | C | 60 | 19.9 | 13434 | 2025-12-15 08:04:46 | MASTER-OAFA | (07h 11m 59.20s , -44d 06m 31.8s) | C | 60 | 20.1 | 13510 | 2025-12-15 08:06:02 | MASTER-OAFA | (07h 11m 53.69s , -44d 07m 07.7s) | C | 60 | 20.1 | 13588 | 2025-12-15 08:07:19 | MASTER-OAFA | (07h 11m 53.62s , -44d 06m 07.0s) | C | 60 | 20.1 | 13663 | 2025-12-15 08:08:34 | MASTER-OAFA | (07h 00m 50.69s , -44d 07m 25.0s) | C | 60 | 20.1 | 13738 | 2025-12-15 08:09:49 | MASTER-OAFA | (07h 00m 44.20s , -44d 08m 24.8s) | C | 60 | 20.1 | 13812 | 2025-12-15 08:11:03 | MASTER-OAFA | (07h 00m 49.56s , -44d 08m 05.9s) | C | 60 | 20.0 | 13890 | 2025-12-15 08:12:21 | MASTER-OAFA | (07h 15m 57.41s , -40d 19m 43.9s) | C | 60 | 19.7 | 13966 | 2025-12-15 08:13:37 | MASTER-OAFA | (07h 26m 31.11s , -40d 17m 39.3s) | C | 60 | 19.5 | 14043 | 2025-12-15 08:14:54 | MASTER-OAFA | (07h 15m 54.78s , -40d 18m 47.7s) | C | 60 | 19.6 | 14120 | 2025-12-15 08:16:11 | MASTER-OAFA | (07h 26m 24.87s , -40d 17m 30.7s) | C | 60 | 19.4 | 14197 | 2025-12-15 08:17:28 | MASTER-OAFA | (07h 16m 00.19s , -40d 18m 46.2s) | C | 60 | 19.4 | 14275 | 2025-12-15 08:18:46 | MASTER-OAFA | (07h 42m 53.06s , -47d 55m 28.5s) | C | 60 | 19.4 | 14352 | 2025-12-15 08:20:03 | MASTER-OAFA | (07h 42m 57.59s , -47d 55m 10.4s) | C | 60 | 19.3 | 14427 | 2025-12-15 08:21:18 | MASTER-OAFA | (07h 42m 55.69s , -47d 53m 44.8s) | C | 60 | 19.3 | 14504 | 2025-12-15 08:22:35 | MASTER-OAFA | (07h 30m 58.35s , -47d 55m 18.9s) | C | 60 | 19.3 | 14579 | 2025-12-15 08:23:50 | MASTER-OAFA | (07h 31m 01.75s , -47d 53m 57.1s) | C | 60 | 19.3 | 14655 | 2025-12-15 08:25:06 | MASTER-OAFA | (07h 30m 55.68s , -47d 54m 41.6s) | C | 60 | 19.2 | 14732 | 2025-12-15 08:26:23 | MASTER-OAFA | (07h 19m 09.09s , -42d 11m 42.9s) | C | 60 | 18.9 | 14811 | 2025-12-15 08:27:42 | MASTER-OAFA | (07h 19m 16.77s , -42d 12m 42.0s) | C | 60 | 18.8 | 14886 | 2025-12-15 08:28:57 | MASTER-OAFA | (07h 19m 09.57s , -42d 13m 41.9s) | C | 60 | 18.7 | 14967 | 2025-12-15 08:30:18 | MASTER-OAFA | (07h 20m 16.60s , -47d 54m 16.6s) | C | 60 | 18.7 | 15042 | 2025-12-15 08:31:33 | MASTER-OAFA | (07h 20m 11.22s , -47d 54m 54.2s) | C | 60 | 18.5 | 15122 | 2025-12-15 08:32:53 | MASTER-OAFA | (07h 48m 34.22s , -45d 59m 04.2s) | C | 60 | 18.2 | 15200 | 2025-12-15 08:34:11 | MASTER-OAFA | (07h 48m 40.65s , -46d 00m 03.4s) | C | 60 | 18.1 | 15278 | 2025-12-15 08:35:29 | MASTER-OAFA | (07h 48m 34.37s , -46d 01m 03.0s) | C | 60 | 18.0 | 15353 | 2025-12-15 08:36:44 | MASTER-OAFA | (07h 37m 07.92s , -46d 01m 09.9s) | C | 60 | 14.4 | 84349 | 2025-12-16 03:46:40 | MASTER-OAFA | (06h 42m 04.68s , -46d 22m 13.0s) | C | 60 | 20.1 | 84423 | 2025-12-16 03:47:55 | MASTER-OAFA | (06h 42m 11.05s , -46d 21m 55.7s) | C | 60 | 20.1 | 84501 | 2025-12-16 03:49:12 | MASTER-OAFA | (06h 42m 08.07s , -46d 20m 26.7s) | C | 60 | 20.1 | 85037 | 2025-12-16 03:58:08 | MASTER-OAFA | (07h 03m 41.56s , -38d 45m 25.1s) | C | 60 | 20.0 | 85111 | 2025-12-16 03:59:22 | MASTER-OAFA | (07h 03m 39.52s , -38d 43m 41.8s) | C | 60 | 20.0 | 85186 | 2025-12-16 04:00:37 | MASTER-OAFA | (07h 03m 39.60s , -38d 45m 13.1s) | C | 60 | 20.0 | 85269 | 2025-12-16 04:02:00 | MASTER-OAFA | (07h 13m 56.14s , -38d 43m 24.5s) | C | 60 | 19.9 | 85346 | 2025-12-16 04:03:17 | MASTER-OAFA | (07h 13m 49.92s , -38d 44m 16.0s) | C | 60 | 19.9 | 85426 | 2025-12-16 04:04:37 | MASTER-OAFA | (07h 13m 50.59s , -38d 43m 13.4s) | C | 60 | 19.9 | 86212 | 2025-12-16 04:17:43 | MASTER-OAFA | (07h 00m 35.46s , -50d 09m 13.0s) | C | 60 | 20.0 | 86286 | 2025-12-16 04:18:57 | MASTER-OAFA | (07h 00m 41.92s , -50d 08m 46.7s) | C | 60 | 19.9 | 86361 | 2025-12-16 04:20:12 | MASTER-OAFA | (07h 00m 39.05s , -50d 07m 11.0s) | C | 60 | 19.9 | 86437 | 2025-12-16 04:21:28 | MASTER-OAFA | (07h 13m 05.48s , -50d 08m 41.6s) | C | 60 | 19.9 | 86511 | 2025-12-16 04:22:42 | MASTER-OAFA | (07h 13m 09.00s , -50d 07m 10.9s) | C | 60 | 19.9 | 86586 | 2025-12-16 04:23:57 | MASTER-OAFA | (07h 13m 03.32s , -50d 08m 00.5s) | C | 60 | 19.9 | 87136 | 2025-12-16 04:33:07 | MASTER-OAFA | (07h 11m 30.33s , -34d 54m 46.1s) | C | 60 | 20.0 | 88145 | 2025-12-16 04:49:56 | MASTER-OAFA | (06h 39m 07.90s , -44d 26m 10.3s) | C | 60 | 20.2 | 88223 | 2025-12-16 04:51:14 | MASTER-OAFA | (06h 39m 04.26s , -44d 24m 24.1s) | C | 60 | 20.2 | 88298 | 2025-12-16 04:52:29 | MASTER-OAFA | (06h 39m 04.43s , -44d 25m 58.7s) | C | 60 | 20.2 | 88374 | 2025-12-16 04:53:45 | MASTER-OAFA | (06h 50m 17.94s , -44d 24m 16.0s) | C | 60 | 20.3 | 88449 | 2025-12-16 04:55:00 | MASTER-OAFA | (06h 50m 11.51s , -44d 25m 01.4s) | C | 60 | 20.3 | 88528 | 2025-12-16 04:56:19 | MASTER-OAFA | (06h 50m 11.32s , -44d 23m 59.0s) | C | 60 | 20.3 | 89158 | 2025-12-16 05:06:49 | MASTER-OAFA | (06h 49m 31.52s , -50d 05m 36.2s) | C | 60 | 20.0 | 89232 | 2025-12-16 05:08:03 | MASTER-OAFA | (06h 49m 37.28s , -50d 06m 33.8s) | C | 60 | 20.1 | 92863 | 2025-12-16 06:08:34 | MASTER-OAFA | (07h 21m 43.31s , -44d 22m 47.0s) | C | 60 | 20.3 | 92938 | 2025-12-16 06:09:49 | MASTER-OAFA | (07h 32m 48.01s , -44d 23m 39.5s) | C | 60 | 20.2 | 93015 | 2025-12-16 06:11:06 | MASTER-OAFA | (07h 21m 44.03s , -44d 23m 25.4s) | C | 60 | 20.2 | 93096 | 2025-12-16 06:12:27 | MASTER-OAFA | (07h 32m 51.29s , -44d 21m 59.3s) | C | 60 | 20.2 | 93171 | 2025-12-16 06:13:42 | MASTER-OAFA | (07h 21m 42.00s , -44d 23m 19.6s) | C | 60 | 20.3 | 94066 | 2025-12-16 06:28:37 | MASTER-OAFA | (07h 28m 39.67s , -42d 29m 10.7s) | C | 60 | 19.9 | 94142 | 2025-12-16 06:29:53 | MASTER-OAFA | (07h 39m 31.59s , -42d 27m 32.3s) | C | 60 | 19.6 | 94221 | 2025-12-16 06:31:12 | MASTER-OAFA | (07h 28m 37.80s , -42d 28m 18.8s) | C | 60 | 19.9 | 94300 | 2025-12-16 06:32:31 | MASTER-OAFA | (07h 39m 25.23s , -42d 27m 09.1s) | C | 60 | 19.6 | 94378 | 2025-12-16 06:33:49 | MASTER-OAFA | (07h 28m 43.67s , -42d 28m 15.8s) | C | 60 | 19.9 | 94457 | 2025-12-16 06:35:08 | MASTER-OAFA | (07h 14m 55.59s , -46d 17m 09.1s) | C | 60 | 20.3 | 94532 | 2025-12-16 06:36:23 | MASTER-OAFA | (07h 26m 24.14s , -46d 15m 26.7s) | C | 60 | 20.3 | 94618 | 2025-12-16 06:37:49 | MASTER-OAFA | (07h 14m 52.84s , -46d 16m 51.5s) | C | 60 | 20.3 | 94698 | 2025-12-16 06:39:09 | MASTER-OAFA | (07h 26m 27.32s , -46d 15m 19.6s) | C | 60 | 20.3 | 94777 | 2025-12-16 06:40:28 | MASTER-OAFA | (07h 14m 49.66s , -46d 16m 04.5s) | C | 60 | 20.3 | 94857 | 2025-12-16 06:41:48 | MASTER-OAFA | (07h 24m 42.74s , -50d 03m 42.8s) | C | 60 | 20.1 | 94933 | 2025-12-16 06:43:05 | MASTER-OAFA | (07h 37m 02.25s , -50d 04m 35.0s) | C | 60 | 20.1 | 95011 | 2025-12-16 06:44:22 | MASTER-OAFA | (07h 24m 42.56s , -50d 04m 27.0s) | C | 60 | 20.1 | 95086 | 2025-12-16 06:45:37 | MASTER-OAFA | (07h 37m 05.24s , -50d 02m 34.5s) | C | 60 | 20.1 | 95163 | 2025-12-16 06:46:54 | MASTER-OAFA | (07h 24m 40.87s , -50d 04m 29.3s) | C | 60 | 20.2 | 95241 | 2025-12-16 06:48:12 | MASTER-OAFA | (07h 32m 59.73s , -44d 21m 03.7s) | C | 60 | 20.2 | 95315 | 2025-12-16 06:49:26 | MASTER-OAFA | (07h 32m 54.82s , -44d 21m 44.8s) | C | 60 | 20.2 | 95481 | 2025-12-16 06:52:12 | MASTER- | (07h 06m 46.38s , -42d 16m 40.2s) | C | 60 | 17.9 | 95481 | 2025-12-16 06:52:12 | MASTER- | (06h 57m 42.70s , -43d 15m 17.5s) | C | 60 | 17.5 | 95552 | 2025-12-16 06:53:23 | MASTER- | (06h 59m 10.83s , -44d 11m 26.1s) | C | 60 | 17.7 | 95552 | 2025-12-16 06:53:23 | MASTER- | (06h 49m 48.76s , -45d 10m 03.7s) | C | 60 | 17.7 | 95627 | 2025-12-16 06:54:38 | MASTER- | (07h 34m 21.14s , -40d 22m 55.6s) | C | 60 | 17.7 | 95627 | 2025-12-16 06:54:38 | MASTER- | (07h 25m 32.71s , -41d 21m 43.9s) | C | 60 | 17.6 | 96781 | 2025-12-16 07:13:52 | MASTER- | (07h 21m 39.36s , -44d 10m 20.1s) | C | 60 | 17.6 | 96781 | 2025-12-16 07:13:53 | MASTER- | (07h 09m 40.36s , -45d 07m 52.4s) | C | 60 | 17.6 | 96854 | 2025-12-16 07:15:05 | MASTER- | (06h 52m 49.25s , -46d 05m 58.2s) | C | 60 | 17.9 | 96854 | 2025-12-16 07:15:05 | MASTER- | (06h 40m 24.86s , -47d 03m 27.2s) | C | 60 | 17.6 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/43136. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41217] EP251214a: Optical upper limit with Kinder observations
by GCN Circulars 16 Dec '25

16 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43135 SUBJECT: EP251214a: Optical upper limit with Kinder observations DATE: 25/12/16 04:56:08 GMT FROM: Janet Chen at National Central University <janetstars(a)gmail.com> A. Aryan, T.-W. Chen, H.-Y. Hsiao, C.-S. Lin (all NCU), A. K. H. Kong (NTHU), J. Gillanders, S. J. Smartt (both Oxford), Y. J. Yang (NYUAD), Y.-H. Lee, A. Sankar.K, Y.-C. Pan, C.-C. Ngeow, M.-H. Lee, C.-H. Lai, W.-J. Hou, H.-C. Lin,J.-K. Guo (all NCU), S. Yang, Z. N. Wang, L. L. Fan, G. H. Sun (all HNAS), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, T. Moore, K. W. Smith, C. Angus, A. Aamer (all QUB), A. Schultz and M. Huber (both IfA, Hawaii) report: We observed the field of the fast X-ray transient EP251214a (Yin et al., GCN 43087; GCN 43102) using the 40 cm SLT at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen & Yang et al., 2025, ApJ, 983, 86, doi:10.3847/1538-4357/adb428). The first SLT epoch of observations started at 16:25 UTC on the 14th of December 2025 (MJD 61023.684), 13.97 hr after the EP-WXT trigger. We utilized the astroalign (Beroiz et al. 2020, A&C, 32, 100384) and astropy (Astropy Collaboration et al. 2022, ApJ, 935, 167) packages to align and stack the individual frames. We utilized the Python-based package AutoPhOT (Brennan & Fraser, 2022, A&A, 667, A62) to perform template subtraction with the Pan-STARRS1 3Pi (Chambers et al., 2016 arXiv:1612.05560) image using the 'sfft' (Hu et al., 2022, ApJ, 936, 157) algorithm. We do not find any evidence of a new and uncataloged optical counterpart candidate within the 3.1 arcminute error circle of the EP-WXT localization in either the stacked or the difference image. Moreover, we further utilized AutoPhOT to perform PSF photometry. The details of the observations and the measured upper limit (in the AB system) are as follows: Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | avg. Seeing | med. Airmass SLT | i | 61023.684 | 13.97 | 300 * 24 | >21.9 | 1".3 | 1.30 Our non-detection is consistent with Basa et al. (GCN 43092); Lipunov et al. (GCN 43099); Zheng et al. (GCN 43110). The absence of any associated optical counterpart down to 21.9 mag with the optical observations starting within 24 hours of its X-ray discovery aligns well with the 'Dark' nature of FXTs (Aryan et al., 2025, ApJS, 281, 20, doi:10.3847/1538-4365/adfc69). The presented magnitude is calibrated using the field stars from the Pan-STARRS DR2 catalog and is not corrected for the expected Galactic foreground extinction of A_i = 0.05 mag in the direction of the transient (Schlafly & Finkbeiner, 2011). The methodology, details on the Lulin observatory telescopes, and a compilation of our optical follow-up campaign for FXTs discovered within the first year of operation of the Einstein-Probe mission can be found in Aryan et al. (2025). View this GCN Circular online at https://gcn.nasa.gov/circulars/43135. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41216] GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
by GCN Circulars 16 Dec '25

16 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43134 SUBJECT: GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras DATE: 25/12/16 04:17:28 GMT FROM: Brajesh Kumar at SWIFAR, YNU <brajesh(a)ynu.edu.cn> Weikang Lin, Guowang Du, Ziwei Li, Brajesh Kumar, Jiayu Qi, Donglin Gao, Yu Pan, Yuan Fang, Xinlei Chen, Xingzhu Zou, Xufeng Zhu, Tao Wang, Jinghua Zhang, Xinzhong Er, Yuanpei Yang, Xiangkun Liu, Xiaowei Liu (SWIFAR, YNU) report on behalf of the Mephisto Team: We performed simultaneous multi-band photometric observations of GRB 251214B (Fermi GBM Team, GCN Circ. 43088; Eyles-Ferris et al., GCN Circ. 43089) with the newly installed three mosaic cameras on the 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at the Lijiang Observatory. The observations were initiated at 11:31:54UTC2025-12-14 (~2.5 hours after the Swift/BAT trigger). Multiple frames were obtained in uvgriz - bands. The optical counterpart is detected in the stacked images of g, r bands and single frames of i, z bands, but there is no detection in the u and v band stacked images. The preliminary photometric magnitudes and 3-sigma upper limits are listed below. These magnitudes are not corrected for the Galactic extinction in the direction of the burst. UT Start |Band | Exposure(s)| mag/LimMag (AB) ---------------------|-----|------------|---------------- 2025-12-14T11:49:07 | u | 300.0*2 | >22.68 2025-12-14T11:31:54 | v | 300.0*2 | >22.47 2025-12-14T11:49:09 | g | 300.0*2 | 21.08 (+/-0.12) 2025-12-14T11:31:56 | r | 300.0*2 | 20.64 (+/-0.08) 2025-12-14T11:49:09 | i | 300.0 | 19.50 (+/-0.07) 2025-12-14T11:31:56 | z | 300.0 | 18.60 (+/-0.14) The optical detection of the burst is consistent with Eyles-Ferris et al. 2025 (GCN 43089); Kang et al. 2025 (GCN 43093); Gress et al. 2025 (GCN 43095); Fu et al. 2025 (GCN 43097); Gupta et al. 2025 (GCN 43100); Watson et al. (GCN 43103); Kuin et al. (GCN 43105); Pérez-Fournon (GCN 43123); Volnova et al. (GCN 43124); Postigo et al. (GCN 43131). ------------------------------------------------------------------------------------------------- Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6-m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. It provides real-time, high-quality colors of stellar objects. The Mephisto mosaic cameras were installed in October 2025. The first light was achieved in all three channels on 10 October 2025, and these are currently in the commissioning phase. Here, we note that the current data processing pipeline is still at a preliminary stage, with flux calibration precision in each band at the level of about 5% or even higher. ------------------------------------------------------------------------------------------------- View this GCN Circular online at https://gcn.nasa.gov/circulars/43134. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41215] GRB 251215A: Glowbug gamma-ray detection
by GCN Circulars 15 Dec '25

15 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43133 SUBJECT: GRB 251215A: Glowbug gamma-ray detection DATE: 25/12/15 23:10:15 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251215A, which was also detected by Fermi/GBM (GCN 43104), Swift/BAT-GUANO (GCN 43114), and CALET (trigger 1449807236). Glowbug was in the SAA at the time of the GBM T0 (04:21:21) and recorded data beginning at T0+20s, initially with high background rates as it was exiting the SAA. Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-12-15 04:22:25.800 with a duration of 76.0 s and a total significance of about 23.8 sigma. The burst originated toward the Nadir side of Glowbug and was detected despite passing through the passive material from the H9 pallet and internal passive material/shielding within Glowbug. The Glowbug onset is 64.8 s after the GBM T0, and the Glowbug light curve comprises three peaks at ~T0+1s, ~T0+25s, and ~T0+72s; the T0+72s peak matches the CALET trigger time (04:23:36.282). The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/43133. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41214] GRB 251214B: UAFO optical upper limit
by GCN Circulars 15 Dec '25

15 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43132 SUBJECT: GRB 251214B: UAFO optical upper limit DATE: 25/12/15 18:11:38 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> N. S. Pankov (HSE, IKI), A. Kochergin (UAFO IAA), A. A. Volnova (IKI), A. S. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the long GRB 251214B detected by Fermi (Fermi team, GCN 43088), Swift (Eyles-Ferris et al., GCN 43089; Evans et al., GCN 43098; Kuin and Eyles-Ferris, GCN 43105; Burrows et al., GCN 43112; Laha et al., GCN 43129), and GECAM-B (Luo et al., GCN 43113) with the RC-500 (0.5m) telescope of Ussuriysk Astrophysical Observatory (UAFO) taking several frames in R-band. The observations started on Dec. 14 at 10:44 UT, i.e., ~ 1.5 hours after the Swift/BAT trigger. In the stacked image we do not detect the optical counterpart reported previously (Eyles-Ferris et al., GCN 43089; Kang et al., GCN 43093; Gress et al., GCN 43095; Fu et al., GCN 43097; Gupta et al., GCN 43100; Watson et al., GCN 43103; Kuin and Eyles-Ferris, GCN 43105; Pérez-Fournon et al., GCN 43123; Volnova et al., GCN 43124; de Ugarte Postigo et al., GCN 43131). Photometry and observational details are the following: Date UT start t-T0 Exp. Filter Obj. Err. UL Site/Telescope (mid,days) (n*s) (3sigma) 2025-12-14 10:44:26 0.09073 57*60 R n/d n/d 19.4 UAFO/RC500 The photometry is based on several nearby stars from the USNO-B1 catalogue (R2 magnitudes) and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/43132. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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