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[vsnet-grb-info 41182] GRB 251208C: GECAM-B observation of a likely long burst
by GCN Circulars 15 Dec '25

15 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43101 SUBJECT: GRB 251208C: GECAM-B observation of a likely long burst DATE: 25/12/15 01:08:35 GMT FROM: Xinghao Luo at SVOM/GRN <2952704891(a)qq.com> Xing-Hao Luo, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered on-ground by GRB 251214A, at 2025-12-14T00:11:15.200 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43085). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 5.0 +1.0/-2.5s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb251214A.png Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/43101. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41181] GRB 251214B: 1.3m DFOT optical detection
by GCN Circulars 14 Dec '25

14 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43100 SUBJECT: GRB 251214B: 1.3m DFOT optical detection DATE: 25/12/14 20:36:58 GMT FROM: ANSHIKA GUPTA at ARIES <anshika05180(a)gmail.com> Anshika Gupta, Dhruv Jain, Pankaj Pawar, Debalina Kar, and Kuntal Misra (ARIES) report: We observed the field of GRB 251214B detected by Fermi/GBM (Fermi GBM team, GCN 43088) and Swift/BAT (Eyles-Ferris et al. 2025, GCN 43089) with the 1.3m Devasthal Fast Optical Telescope (DFOT), located at the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2025-12-14 at 12:59:37 UT, i.e., ~ 3.95 hours after the Fermi/GBM trigger. We have taken multiple frames with an exposure time of 300s in the I filter. We stacked the images after the alignment. We detect an optical afterglow in our stacked image within the error box of Swift/UVOT (Eyles-Ferris et al. 2025, GCN 43089). We obtain the following preliminary magnitude in the stacked image: Date Start_UT T_start-T0 (hour) Filter Exp time (s) Magnitude =============================================================== 2025-12-14 12:59:37 ~3.95 I 300s*18 20.03 +/-0.03 The optical detection of the burst is consistent with Eyles-Ferris et al. 2025 (GCN 43089); Lipunov et al. 2025 (GCN 43091); Kang et al. 2025 (GCN 43093); Gress et al. 2025 (GCN 43095); and Fu et al. 2025 (GCN 43097). The magnitude is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalogue. View this GCN Circular online at https://gcn.nasa.gov/circulars/43100. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41180] EP251214a: Global MASTER-Net observations report
by GCN Circulars 14 Dec '25

14 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43099 SUBJECT: EP251214a: Global MASTER-Net observations report DATE: 25/12/14 19:09:20 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-Tunka robotic telescope [1] located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the EP251214a ( EP Team et al., GCN 43087) errorbox 23345 sec after notice time and 44450 sec after trigger time at 2025-12-14 14:47:51 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 80 deg. The sun altitude is -52.2 deg. The galactic latitude b = 50 deg., longitude l = 212 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3070739 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 11367 | 2025-12-14 05:35:57 | MASTER- | (09h 49m 46.34s , +21d 15m 33.3s) | C | 60 | 17.1 | 12140 | 2025-12-14 05:48:51 | MASTER- | (09h 47m 03.54s , +20d 23m 17.9s) | C | 60 | 18.1 | 12140 | 2025-12-14 05:48:51 | MASTER- | (09h 58m 23.13s , +19d 21m 03.2s) | C | 60 | 17.0 | 12427 | 2025-12-14 05:53:37 | MASTER- | (09h 54m 39.28s , +22d 17m 23.3s) | C | 60 | 18.4 | 28176 | 2025-12-14 10:15:06 | MASTER- | (09h 45m 41.72s , +21d 23m 05.5s) | C | 180 | 19.6 | 28176 | 2025-12-14 10:15:06 | MASTER- | (09h 57m 15.83s , +20d 21m 58.5s) | C | 180 | 19.3 | 44480 | 2025-12-14 14:47:51 | MASTER-Tunka | (09h 53m 14.05s , +20d 49m 09.6s) | C | 60 | 18.4 | 57811 | 2025-12-14 18:30:01 | MASTER-Tunka | (09h 50m 07.21s , +22d 38m 41.9s) | C | 60 | 20.0 | 57812 | 2025-12-14 18:30:02 | MASTER-Tunka | (09h 49m 36.25s , +22d 46m 24.5s) | C | 60 | 19.6 | 59105 | 2025-12-14 18:51:35 | MASTER-Tunka | (09h 58m 44.22s , +20d 43m 39.4s) | C | 60 | 19.6 | 59105 | 2025-12-14 18:51:35 | MASTER-Tunka | (09h 58m 13.62s , +20d 51m 19.9s) | C | 60 | 19.1 | 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/43099. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41179] GRB 251214B: Enhanced Swift-XRT position
by GCN Circulars 14 Dec '25

14 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43098 SUBJECT: GRB 251214B: Enhanced Swift-XRT position DATE: 25/12/14 17:09:40 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 1446 s of XRT Photon Counting mode data and 1 UVOT images for GRB 251214B, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 330.21069, -9.16291 which is equivalent to: RA (J2000): 22h 00m 50.57s Dec (J2000): -09d 09' 46.5" with an uncertainty of 2.1 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at https://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43098. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41178] GRB 251214B: Xinglong-2.16m optical observation
by GCN Circulars 14 Dec '25

14 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43097 SUBJECT: GRB 251214B: Xinglong-2.16m optical observation DATE: 25/12/14 13:15:50 GMT FROM: syfu(a)nao.cas.cn S.Y. Fu(HUST), D. Xu, Y.N. Zhu, P.L. Du, J.J. Jin, Z. Fan, X. Liu, L.B. He, J. An, S.Q. Jiang, Z.P. Zhu, J.J. Jia(NAOC) We observed the field of GRB 251214B detected by Swift (Eyles-Ferris et al., GCN 43089) using the Xinglong-2.16m telescope equipped with the BFOSC camera. Observations started at 10:26:38 UT on 2025-12-14 (i.e., 1.41 h after the trigger), and a series of r- / g-band frames have been obtained. The optical afterglow (Eyles-Ferris et al., GCN 43089; Kang et al., GCN 43093; Gress et al., GCN 43095) was clearly detected in our stacked frame with a magnitude of r = 19.40 +- 0.03 at a mid-time of 1.53 hr and g = 20.63 +- 0.09 at a mid-time of 1.88 hr, respectively, calibrated with Pan-STARRS1 DR2 catalog and not corrected for Galactic extinction. We thank the staff at Xinglong observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/43097. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41177] GRB 251214C: Fermi GBM Final Localization
by GCN Circulars 14 Dec '25

14 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43096 SUBJECT: GRB 251214C: Fermi GBM Final Localization DATE: 25/12/14 13:08:43 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> The Fermi GBM team reports the detection of a likely LONG GRB "At 09:17:32.51 UT on 14 December 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251214C (trigger 787396657/251214387). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 346.3, Dec = 41.0 (J2000 degrees, equivalent to J2000 23h 05m, +41d 0'), with a statistical uncertainty of 6.0 degrees. The angle from the Fermi LAT boresight is 138 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251214387/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251214387/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251214387/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/43096. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41176] GRB 251214B : MASTER optical afterglow detection
by GCN Circulars 14 Dec '25

14 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43095 SUBJECT: GRB 251214B : MASTER optical afterglow detection DATE: 25/12/14 12:55:36 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> O.A.Gress, N.M.Budnev (ISU), V.M.Lipunov, P.Balanutsa, I.Panchenko, A.Kuznetsov, E.Gorbovskoy, G.Antipov, N. Tiurina, Ya.Kechin,A.Chasovnikov, D.Vlasenko, V.Shumkov, I.Ionov, Yu.Tselik(Lomonosov MSU, SAI, Moscow), R.Mirgazov, A.Diachok, O.Ershova (Irkutsk State University), R. Podesta, C.Francile, F. Podesta, E. Gonzalez (OAFA, San JuanUni.,Argentina); D.Buckley (SAAO), A. Sosnovskij (CrAO RAS), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysic Observatory, Mexico) V.M.Pillet, R.Rebolo Lopez (The Instituto de Astrofisica de Canarias,Spain) MASTER OT J220050.55-090945.8 detection MASTER-Tunka robotic telescope of MASTER Global Robotic Net (Lipunov et al. [1-4], http://observ.pereplet.ru ), started Fermi (GCN 43088) and Swift (GCN 43089) GRB 251214B error-box observations after sunset at 2025-12-14 10:20:46 UT (Lipunov et al. GCN 43091, cover map https://master.sai.msu.ru/site/master2/event.php?id=3070779 ) MASTER auto-detection system found optical afterglow at summary images MASTER OT J220050.55-090945.8 , discovered by Swift (Eyles-Ferris et al. GCN 430089) and also observed by SVOM (Zhe Kang et al. GCN 43093) with unfiltered m_OT=19.5m at 2025-12-14 10:49:16UT. There is SDSS galaxy (poss.host) in 0.067" in VIZIER database with z_phot=0.6634 Observation and reduction will continue. [1] Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L [2] Lipunov et al. 2022, Universe, Vol. 8(5), id.271 [3] Lipunov et a. 2019, ARep, vol.63, 293 [4] Lipunov V., Kornilov V., Gorbovskoy E., Tiurina N., Kuznetsov A. 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics,Lomonosov MSU PRESS, 591pp. http://www.pereplet.ru/lipunov/625.html#625 View this GCN Circular online at https://gcn.nasa.gov/circulars/43095. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41175] Fermi trigger No 787396657: Global MASTER-Net observations report
by GCN Circulars 14 Dec '25

14 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43094 SUBJECT: Fermi trigger No 787396657: Global MASTER-Net observations report DATE: 25/12/14 12:15:41 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-Tunka robotic telescope [1] located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB251214.39 (trigger No 787396657,23h 11m 00.00s , +35d 42m 36.0s, R=7.23) errorbox 7860 sec after notice time and 7881 sec after trigger time at 2025-12-14 11:28:54 UT, with upper limit up to 19.8 mag. The observations began at zenith distance = 17 deg. The sun altitude is -22.1 deg. The galactic latitude b = -23 deg., longitude l = 102 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3070847 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 7911 | 2025-12-14 11:28:54 | MASTER-Tunka | (23h 18m 11.56s , +35d 35m 58.5s) | C | 60 | 19.8 | 7912 | 2025-12-14 11:28:54 | MASTER-Tunka | (23h 17m 27.54s , +35d 43m 36.3s) | C | 60 | 19.4 | 7984 | 2025-12-14 11:30:06 | MASTER-Tunka | (22h 59m 36.09s , +35d 37m 15.6s) | C | 60 | 19.8 | 7984 | 2025-12-14 11:30:06 | MASTER-Tunka | (22h 58m 52.22s , +35d 44m 52.1s) | C | 60 | 19.5 | 8057 | 2025-12-14 11:31:19 | MASTER-Tunka | (23h 04m 12.06s , +33d 49m 52.3s) | C | 60 | 19.4 | 8057 | 2025-12-14 11:31:19 | MASTER-Tunka | (23h 04m 54.44s , +33d 42m 21.6s) | C | 60 | 19.8 | 8131 | 2025-12-14 11:32:33 | MASTER-Tunka | (23h 14m 26.42s , +37d 31m 33.7s) | C | 60 | 19.7 | 8131 | 2025-12-14 11:32:33 | MASTER-Tunka | (23h 13m 40.85s , +37d 39m 18.2s) | C | 60 | 19.3 | 8206 | 2025-12-14 11:33:48 | MASTER-Tunka | (22h 55m 29.62s , +37d 30m 10.5s) | C | 60 | 19.5 | 8206 | 2025-12-14 11:33:48 | MASTER-Tunka | (22h 54m 44.15s , +37d 37m 53.0s) | C | 60 | 19.1 | 8284 | 2025-12-14 11:35:06 | MASTER-Tunka | (23h 23m 04.59s , +33d 41m 38.5s) | C | 60 | 19.3 | 8284 | 2025-12-14 11:35:06 | MASTER-Tunka | (23h 22m 22.17s , +33d 49m 10.3s) | C | 60 | 18.9 | 8362 | 2025-12-14 11:36:24 | MASTER-Tunka | (22h 53m 50.59s , +31d 47m 07.2s) | C | 60 | 19.1 | 8362 | 2025-12-14 11:36:24 | MASTER-Tunka | (22h 53m 09.70s , +31d 54m 28.8s) | C | 60 | 18.7 | 8437 | 2025-12-14 11:37:39 | MASTER-Tunka | (23h 11m 37.14s , +31d 48m 53.9s) | C | 60 | 19.1 | 8437 | 2025-12-14 11:37:39 | MASTER-Tunka | (23h 10m 56.14s , +31d 56m 17.6s) | C | 60 | 18.6 | 8512 | 2025-12-14 11:38:54 | MASTER-Tunka | (22h 46m 46.23s , +33d 40m 52.2s) | C | 60 | 19.3 | 8512 | 2025-12-14 11:38:54 | MASTER-Tunka | (22h 46m 03.98s , +33d 48m 19.6s) | C | 60 | 18.8 | 8671 | 2025-12-14 11:41:33 | MASTER-Tunka | (22h 51m 47.69s , +39d 31m 45.6s) | C | 60 | 19.0 | 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/43094. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41174] GRB 251214B: SVOM/C-GFT optical observations
by GCN Circulars 14 Dec '25

14 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43093 SUBJECT: GRB 251214B: SVOM/C-GFT optical observations DATE: 25/12/14 11:59:55 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Zhe Kang (CHO), Chao WU (NAOC), Liping Xin(NAOC), Xuhui Han(NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao(NAOC), Yulei Qiu(NAOC), Jing Wang (NAOC), Jinsong Deng(NAOC), Lei Huang(NAOC), Jianyan Wei (NAOC), report on behalf of the SVOM/C-GFT team: We observed the field of GRB 251214B detected by Fermi/GBM (Fermi GBM team, GCN 43088) and Swift/BAT (Eyles-Ferris et al., GCN 43089) with LATIOS on SVOM/C-GFT. Observations started at 2025-12-14T09:12:24 UTC, ~10.12 min after the trigger. The optical counterpart (Eyles-Ferris et al., GCN 43089) was clearly detected in our stacked images of band g, r , and i. The magnitudes are: |[date-obs(mid-time)] | Mid_t-T0(min) | exposure time (s) | band | mag (AB) | mag_err| |--------------------|--------------|-------------------|------|----------|--------| |2025-12-14T09:12:42 | 10.75 | 3x10 | i | 16.56 |0.070| |2025-12-14T09:26:55 | 24.64 | 5x30 | g | 18.56 |0.090| |2025-12-14T09:40:03 | 37.77 | 6x30 | r | 18.33 |0.050| The photometry was calibrated against UCAC4 catalogue and no correction for Galactic dust extinction was applied. We thank the observation assistants Chun-Lei Guo and Yin-Huai Hao at Jilin observatory for their excellent support. The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec x 21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching. View this GCN Circular online at https://gcn.nasa.gov/circulars/43093. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 41173] EP251214a: COLIBRÍ optical upper limit
by GCN Circulars 14 Dec '25

14 Dec '25

TITLE: GCN CIRCULAR NUMBER: 43092 SUBJECT: EP251214a: COLIBRÍ optical upper limit DATE: 25/12/14 11:44:06 GMT FROM: Stephane Basa at UAR Pytheas/OHP, LAM <stephane.basa(a)lam.fr> Stéphane Basa (UAR Pytheas), Leonardo García García (UNAM), Noémie Globus (UNAM), Benjamin Schneider (LAM), Jean-Grégoire Ducoin (CPPM), William H. Lee (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (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 EP251214a (Y.-H. I. Yin et al., GCN Circ. 43087) potentially associated with GRB 251214A reported by the Fermi GBM Team (GCN Circ. 43085), using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2025-12-14 at 09:12:10.65 to 09:56:13.15 UTC (from 6.75 to 7.49 hr after the trigger) and obtained 32 minutes of simultaneous exposure in the r and z filters. The data were reduced, coadded and analyzed with the COLIBRÍ pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and was not corrected for Galactic extinction. In the stacked image, we do not detect any new source at the WXT uncertainty region (Y.-H. I. Yin et al., GCN Circ. 43087) down to the following 5-sigma limit: r > 23.1 z > 21.6 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/43092. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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