//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29736 SUBJECT: GRB 210330A: GECAM detection DATE: 21/03/30 15:03:05 GMT FROM: Shaolin Xiong at IHEP D. Y. Guo, Y. Huang, S. L. Xiong, S. Xiao, C. Cai, Y. Zhao, J. C. Liu, Q. B. Yi, Y. Q. Zhang, W. C. Xue, C. Zheng, Z. W. Guo, X. Y. Zhao, X. Y. Song, P. Wang, X. B. Li, W. X. Peng, R. Qiao, C. W. Wang, 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. Q. Li, Y. G. Li, X. H. Liang, J. Y. Liao, J. C. Liu, X. J. Liu, Y. Q. Liu, F. J. Lu, Q. Luo, X. Ma, G. Ou,  D. L. Shi, J. Y. Shi, L. M. Song, G. X. Sun, X. L. Sun, Y. L. Tuo, J. Z. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, S. Yang, M. Yao, B. X. Zhang, C. Y. Zhang, D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang, K. Zhang, P. Zhang, S. N. Zhang, Z. Zhang, S. Y. Zhao, S. J. Zheng, X. Zhou (IHEP), report on behalf of GECAM team: During the commissioning phase, GECAM-B triggered a long burst, GRB 210330A, at 2021-03-30T12:45:46.600 UTC (denoted as T0). GECAM 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 a broad pulses with duration of about 20 s. An automatic on-ground localization was calculated using the light curves and counts spectrum in the BDS alert data. 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: 164.3 deg Dec: -55.6 deg Err: 5.1 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. Given that the location is close to the galactic plane, we cannot rule out the possibility that this burst originated from a galactic source. The GECAM light curve could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_70807546.png The GECAM preliminary location could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_skymap_70807546_V01.png 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: 29738 SUBJECT: GRB 210330A: MASTER optical observation DATE: 21/03/30 21:27:39 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, A.Chasovnikov, F.Balakin, V.Kornilov, E.Gorbovskoy,P.Balanutsa, V.Vladimirov, A.Kuznetsov,K.Zhirkov,D. Vlasenko, N.Tiurina, I.Gorbunov, D.Zimnukhov, V.Senik, V.Topolev, D.Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev (Irkutsk State University, API), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico FelixAguilar OAFA), R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity) MASTER Global robotic net (MASTER-Net:http://observ.pereplet.ru Lipunov et al.,2010,Advances in Astronomy,2010,30L) started GECAM GRB 210330A (D.Y.Guo et al. GCN 29739, Ttrigger=12:45:46.600 UTC, R.A.Dec.: 164.3d,-55.6d, er.-b.=5.1d) optical observations at MASTER-SAAO (located in South African Astronomical Observatory) 17496 sec after trigger time at 2021-03-30 17:37:23 UT at sunset, with upper limit up to 18.7 mag. Observations started at zenith distance = 43 deg. The sun altitude was -13.6 deg. The galactic latitude b = 4 deg., longitude l = 288 deg. Real time updated cover map and OT,that can be discovered, will be available here: https://master.sai.msu.ru/site/master2/observ.php?id=1580304 There are the following upper limits of the first images Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 17587 | 2021-03-30 17:37:23 | MASTER-SAAO | (10h 57m 26.66s , -55d 35m 44.3s) | C | 180 | 18.7 | 17787 | 2021-03-30 17:40:43 | MASTER-SAAO | (10h 57m 26.36s , -55d 34m 44.9s) | C | 180 | 18.6 | 17986 | 2021-03-30 17:44:02 | MASTER-SAAO | (11h 05m 32.80s , -55d 35m 42.8s) | C | 180 | 18.6 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29749 SUBJECT: GRB 210330A: AstroSat CZTI detection DATE: 21/04/03 11:10:00 GMT FROM: Gaurav Waratkar at IIT Bombay P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta (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 210330A, which was also detected by GECAM (GCN #29736). The source was clearly detected in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2021-03-30 12:45:46.50 UT. The measured peak count rate associated with the burst is 262 (+45, -46) cts/s above the background in the combined data of four quadrants, with a total 1367 (+248, -267) cts. The local mean background count rate was 510 (+3, -3) cts/s. Using cumulative rates, we measure a T90 of 13 (+2, -7) s. 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.