December 2023 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 33278] GRB 231224A: Fermi GBM Final Real-time Localization
by GCN Circulars 25 Dec '23

25 Dec '23

TITLE: GCN CIRCULAR NUMBER: 35426 SUBJECT: GRB 231224A: Fermi GBM Final Real-time Localization DATE: 23/12/24 20:59:57 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 SHORT GRB At 20:49:15 UT on 24 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231224A (trigger 725143760.994196 / 231224868). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 102.3, Dec = -71.2 (J2000 degrees, equivalent to J2000 06h 49m, -71d 12'), with a statistical uncertainty of 11.9 degrees. The angle from the Fermi LAT boresight is 24.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231224868/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231224868/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231224868/… View this GCN Circular online at https://gcn.nasa.gov/circulars/35426. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 33277] GRB 231222B: GRBAlpha detection
by GCN Circulars 24 Dec '23

24 Dec '23

TITLE: GCN CIRCULAR NUMBER: 35425 SUBJECT: GRB 231222B: GRBAlpha detection DATE: 23/12/24 10:24:25 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> 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, M. Kolar, L. Szakszonova, 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 231222B (Fermi/GBM detection: GCN 35418; Fermi/LAT detection: GCN 35416; INTEGRAL/SPI-ACS peak detection at 2023-12-22 ~07:26:03 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv:2302.10048). The detection was confirmed at the peak time 2023-12-22 07:26:04 UTC. The T90 duration measured by GRBAlpha is 5 s and the overall significance during T90 reaches 6.2 sigma. The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB231222B_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/35425. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 33276] LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
by GCN Circulars 24 Dec '23

24 Dec '23

TITLE: GCN CIRCULAR NUMBER: 35424 SUBJECT: LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification DATE: 23/12/24 04:34:55 GMT FROM: Aaron Zimmerman at U. of Texas at Austin <aaron.zimmerman(a)utexas.edu> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S231224e (GCN Circular 35423). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S231224e After parameter estimation by RapidPE-RIFT [2], the updated classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (0%). For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 394 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 863 +/- 213 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/userguide/. [1] Ashton et al. ApJS 241, 27 (2019) and Morisaki et al. arXiv:2307.13380 (2023) [2] Rose et al. arXiv:2201.05263 (2022) and Pankow et al. PRD 92, 023002 (2015) View this GCN Circular online at https://gcn.nasa.gov/circulars/35424. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 33275] LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
by GCN Circulars 24 Dec '23

24 Dec '23

TITLE: GCN CIRCULAR NUMBER: 35423 SUBJECT: LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate DATE: 23/12/24 03:24:51 GMT FROM: yuchiung.lin(a)mx.nthu.edu.tw The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S231224e during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2023-12-24 02:43:21.970 UTC (GPS time: 1387421019.970). The candidate was found by the GstLAL [1], MBTA [2], and PyCBC Live [3] analysis pipelines. S231224e is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.5e-09 Hz, or about one in 20 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S231224e The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%). Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [4] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [4] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassgap) is 12%. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [5], distributed via GCN notice about 27 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [5], distributed via GCN notice about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 520 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 904 +/- 237 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/userguide/. [1] Tsukada et al. PRD 108, 043004 (2023) and Ewing et al. arXiv:2305.05625 (2023) [2] Aubin et al. CQG 38, 095004 (2021) [3] Dal Canton et al. ApJ 923, 254 (2021) [4] Chatterjee et al. ApJ 896, 54 (2020) [5] Singer & Price PRD 93, 024013 (2016) View this GCN Circular online at https://gcn.nasa.gov/circulars/35423. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 33274] LIGO/Virgo/KAGRA S231223j: Updated Sky localization
by GCN Circulars 24 Dec '23

24 Dec '23

TITLE: GCN CIRCULAR NUMBER: 35422 SUBJECT: LIGO/Virgo/KAGRA S231223j: Updated Sky localization DATE: 23/12/23 23:55:45 GMT FROM: Aaron Zimmerman at U. of Texas at Austin <aaron.zimmerman(a)utexas.edu> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S231223j (GCN Circular 35420). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.offline0.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S231223j For the Bilby.offline0.multiorder.fits,0 sky map, the 90% credible region is 3520 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 4468 +/- 1602 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/userguide/. [1] Ashton et al. ApJS 241, 27 (2019) and Morisaki et al. arXiv:2307.13380 (2023) View this GCN Circular online at https://gcn.nasa.gov/circulars/35422. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 33273] GRB 231222B: Swift-XRT afterglow detection
by GCN Circulars 23 Dec '23

23 Dec '23

TITLE: GCN CIRCULAR NUMBER: 35421 SUBJECT: GRB 231222B: Swift-XRT afterglow detection DATE: 23/12/23 12:50:08 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M. Ferro (INAF-OAB), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 231222B in a series of observations tiled on the sky. We point out that the burst was improperly named GRB 231222A in GCN Circ 35415, where the tiling was announced. The total exposure time is 4.1 ks, distributed over 4 tiles; the maximum exposure at a single sky location was 2.3 ks. The data were collected between T0+43.2 ks and T0+54.8 ks, and are entirely in Photon Counting (PC) mode. Three uncatalogued X-ray sources are detected, of which one ("Source 1") is believed to be the afterglow. Using 1211 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 251.24744, +19.62084 which is equivalent to: RA (J2000): 16h 44m 59.39s Dec(J2000): +19d 37' 15.0" with an uncertainty of 3.3 arcsec (radius, 90% confidence). This position is 9.3 arcmin from the Fermi/LAT position. The source has a mean count rate of 6.0e-02 ct/sec; we cannot determine at the present time whether it is fading. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.65 (+0.49, -0.29). The best-fitting absorption column is consistent with the Galactic value of 7.1 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.4 x 10^-11 (3.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 7 (+/-14) x 10^20 cm^-2 Galactic foreground: 7.1 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.65 (+0.49, -0.29) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00021639. The results of the full analysis of the tiled XRT observations are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00118. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/35421. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 33272] LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
by GCN Circulars 23 Dec '23

23 Dec '23

TITLE: GCN CIRCULAR NUMBER: 35420 SUBJECT: LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate DATE: 23/12/23 05:28:59 GMT FROM: Yu-Chen Zhou <zhouyuchen21(a)mails.ucas.ac.cn> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S231223j during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2023-12-23 03:28:36.047 UTC (GPS time: 1387337334.047). The candidate was found by the CWB [1], GstLAL [2], MBTA [3], and PyCBC Live [4] analysis pipelines. S231223j is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.1e-09 Hz, or about one in 28 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S231223j The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%). There were noise transients (glitches) in the LIGO Hanford detector near the time of the signal which may affect the parameters or the significance of the candidate. Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [5] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [5] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassgap) is <1%. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [6], distributed via GCN notice about 24 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [6], distributed via GCN notice about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 3342 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1847 +/- 568 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/userguide/. [1] Klimenko et al. PRD 93, 042004 (2016) [2] Tsukada et al. PRD 108, 043004 (2023) and Ewing et al. arXiv:2305.05625 (2023) [3] Aubin et al. CQG 38, 095004 (2021) [4] Dal Canton et al. ApJ 923, 254 (2021) [5] Chatterjee et al. ApJ 896, 54 (2020) [6] Singer & Price PRD 93, 024013 (2016) View this GCN Circular online at https://gcn.nasa.gov/circulars/35420. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 33271] Fermi trigger No 724921799: Global MASTER-Net observations report
by GCN Circulars 23 Dec '23

23 Dec '23

TITLE: GCN CIRCULAR NUMBER: 35419 SUBJECT: Fermi trigger No 724921799: Global MASTER-Net observations report DATE: 23/12/23 03:46:31 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich (Blagoveschensk Educational State University) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB231222.30 (trigger No 724921799,10h 45m 43.20s , -35d 59m 24.0s, R=1.21) errorbox 48203 sec after notice time and 48249 sec after trigger time at 2023-12-22 20:34:04 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 78 deg. The sun altitude is -27.2 deg. The galactic latitude b = 20 deg., longitude l = 277 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2339970 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 48280 | 2023-12-22 20:34:04 | MASTER-SAAO | (10h 37m 19.07s , -36d 39m 28.2s) | C | 60 | 17.5 | 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/35419. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 33270] GRB 231222B: Fermi GBM Detection
by GCN Circulars 23 Dec '23

23 Dec '23

TITLE: GCN CIRCULAR NUMBER: 35418 SUBJECT: GRB 231222B: Fermi GBM Detection DATE: 23/12/23 00:07:56 GMT FROM: Peter Veres at University of Alabama in Huntsville <veresp(a)gmail.com> P. Veres (UAH), V. Sharma (NASA-GSFC/UMBC) and R. Hamburg (CNRS/IN2P3) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 07:26:02.19 UT on 22 December 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231222B (trigger 724922767/231222310). The GRB was also detected by Fermi LAT (Di Lalla et al, GCN 35416). The angle from the Fermi LAT boresight is 19 degrees. The GBM light curve consists of two widely separated pulses with a duration (T90) of about 121 s (50-300 keV). The time-averaged spectrum from T0-5.1 to T0+126.0 s is best fit by a simple power law function with index -1.55 +/- 0.04. The event fluence (10-1000 keV) in this time interval is (5.7 +/- 0.6)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.7 s in the 10-1000 keV band is 6.0 +/- 0.3 ph/s/cm^2. A power law function with an exponential high-energy cutoff fits the spectrum equally well. The power law index is -1.09 +/- 0.16 and the cutoff energy, parameterized as Epeak, is 257 +/- 67 keV. 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/35418. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 33269] LAT GRB231222.31: Global MASTER-Net observations report
by GCN Circulars 23 Dec '23

23 Dec '23

TITLE: GCN CIRCULAR NUMBER: 35417 SUBJECT: LAT GRB231222.31: Global MASTER-Net observations report DATE: 23/12/22 21:55:52 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich (Blagoveschensk Educational State University) MASTER-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the LAT GRB231222.31 (trigger No 724922767,16h 45m 24.00s , +19d 30m 00.0s, R=0.299833) errorbox 9379 sec after notice time and 49215 sec after trigger time at 2023-12-22 21:06:17 UT, with upper limit up to 18.1 mag. The observations began at zenith distance = 81 deg. The sun altitude is -36.5 deg. The galactic latitude b = 36 deg., longitude l = 38 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2340436 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 49278 | 2023-12-22 21:06:17 | MASTER-Tunka | (16h 44m 15.30s , +19d 23m 06.7s) | C | 125 | 14.8 | 51473 | 2023-12-22 21:42:45 | MASTER-Tunka | (16h 44m 16.33s , +19d 24m 26.0s) | C | 140 | 15.2 | 51624 | 2023-12-22 21:45:16 | MASTER-Tunka | (16h 44m 22.24s , +19d 23m 36.0s) | C | 140 | 18.1 | 51733 | 2023-12-22 21:47:50 | MASTER-Tunka | (16h 44m 17.59s , +19d 22m 40.5s) | C | 50 | 17.4 | 51781 | 2023-12-22 21:47:50 | MASTER-Tunka | (16h 44m 17.59s , +19d 22m 40.4s) | C | 145 | 18.1 | Coadd 51794 | 2023-12-22 21:48:50 | MASTER-Tunka | (16h 44m 22.74s , +19d 22m 52.8s) | C | 50 | 17.5 | 51851 | 2023-12-22 21:49:50 | MASTER-Tunka | (16h 44m 20.66s , +19d 24m 35.0s) | C | 45 | 17.5 | 51908 | 2023-12-22 21:50:47 | MASTER-Tunka | (16h 44m 20.65s , +19d 23m 01.1s) | C | 45 | 17.5 | 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/35417. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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