//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29354 SUBJECT: GRB 210126A: BALROG localization (Fermi Trigger / GRB 210126417) DATE: 21/01/26 10:48:07 GMT FROM: Jochen Greiner at MPE,Garching F. Kunzweiler, B. Biltzinger, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger at 10:00:05 on 26 Jan. 2021 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position (1 sigma statistical errors) is: RA(2000.0) = 90.2+/-6.6 deg Decl.(2000.0) = -66.0+/-3.3 deg We estimate an additional systematic error of 1 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB210126417/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB210126417/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB210126417/json //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29356 SUBJECT: GRB 210126A: GECAM detection DATE: 21/01/26 14:16:02 GMT FROM: Shaolin Xiong at IHEP D. Y. Guo, Y. Huang, R. Qiao, X. Ma, P. Zhang, F. J. Lu, S. L. Xiong, S. Xiao, C. Cai, X. Y. Zhao, B. X. Zhang, Z. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo, J. J. He, B. Li, C. Li, C. Y. Li, J. H. Li, Q. X. Li, X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang, J. Y. Liao, J. C. Liu, X. J. Liu, Y. Q. Liu, Q. Luo, G. Ou, W. X. Peng, R. Qiao, D. L. Shi, J. Y. Shi, L. M. Song, X. Y. Song, G. X. Sun, X. L. Sun, Y. L. Tuo, C. W. Wang, J. Z. Wang, P. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, W. C. Xue, S. Yang, M. Yao, Q. B. Yi, C. Y. Zhang, D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang, K. Zhang, S. N. Zhang, Y. Q. Zhang, Z. Zhang, S. Y. Zhao, Y. Zhao, C. Zheng, S. J. Zheng, X. Zhou (IHEP), report on behalf of GECAM team: During the commissioning phase, GECAM-B was triggered in-flight by a long burst at 2021-01-26T10:00:10.600 UTC (denoted as T0). Its alert data was promptly downlinked to the ground through the short message service of BeiDou Navigation Satellite System (BDS). The time latency of the first BeiDou message relative to the trigger time is about 1 minute. According to the BDS alert data, this burst mainly consists of multiple pulses with a duration of roughly 60 s. An automatic on-ground localization was calculated using the light curves and spectrum. Although the in-flight calibration of energy response and localization has not been finalized yet, GECAM-B localized this burst to the following position (J2000): Ra: 112.9 deg Dec: -53.3 deg Galactic lon: 266.6 deg, lat: -20.6 deg Err: 6 deg (1-sigma, statistical only) The current systematic error of location is estimated to be several degrees which could be minimized by the ongoing calibration. The GECAM light curve could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_5-21-4_65354410.png The GECAM preliminary location could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_skymap_65354410_V01.png This burst is temporally and positional coincident with Fermi/GBM trigger (trigNum 633348010, GCN #29354). As the detailed science data are downloaded, all analyses would be improved. Please note that all GECAM results here are preliminary. The final analysis will be published in journal papers or GECAM online catalog. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time), which was funded by the Chinese Academy of Sciences (CAS). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29368 SUBJECT: GRB 210126A: AstroSat CZTI detection DATE: 21/01/29 07:39:06 GMT FROM: Gaurav Waratkar at IIT,Bombay D. Nadella (NITK), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta (IUCAA), P. Sawant (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al, 2020, arxiv:2011.07067) showed detection of a long GRB 210126A, which was also detected by Fermi-GBM (GCN #29354) and GECAM-B (GCN #29356). The source was detected in the 20-200 keV energy range in three quadrants (Quadrant A, C, and D). Quadrant D was noisy, and we excluded it from further analysis. The light curve showed multiple peaks of emission with the strongest peak at 2021-01-26 10:00:07 UT. The measured peak count rate associated with the burst is 56 (+9, -10) cts/s above the background in the combined data of two quadrants, with a total of 1039 (+412, -454) cts. The local mean background count rate was 248 (+1, -1) cts/s. Using cumulative rates, we measure a T90 of 67 (+41, -55) s. These large error bars arise from the presence of a weak second peak whose association with the burst is ambiguous in our data. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.