TITLE: GCN CIRCULAR NUMBER: 38622 SUBJECT: GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission. DATE: 24/12/18 14:58:26 GMT FROM: Diego Gotz at CEA <diego.gotz@cea.fr> D. Götz, H. Goto, P. Ferrando, A. Meuris, M. Moita, C. Plasse, A. Sauvageon (CEA), P. Maggi, L. Michel (ObAS), C. van Hove, F. Robinet, N. Leroy (IJCLab), A. Fort, J. Joubert, K. Mercier, S. Crepaldi (CNES) on behalf of the MXT Commissioning Team, SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Olivier Godet (IRAP), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC), Andrea Goldwurm (APC), Diego Götz (CEA), Xu-Hui Han (NAOC), Cyril Lachaud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs.Paris), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Shaolin Xiong (IHEP), Bing Zhang (UNLV), M. Brunet (IRAP) report on behalf of the SVOM team: GRB 241217A (Brunet et al. GCN 38594, Zhou et al. GCN ​​38606) was observed by SVOM/MXT after an automatic SVOM slew starting at 17:01:09 UT for 12.8 ks (3.5 hr) after the slew. Its position measured with the full MXT dataset is consistent with the one reported by SVOM/VT (Qiu et al. GCN 38600) and Swift/XRT (Williams et al. GCN 38599). After an initial decrease lasting about 300 s, possibly related to the end of the prompt emission, the X-ray light curve enters a bright long lasting emission phase (average 0.5-10 keV flux 8.5e-10 erg/cm2/s) with a superimposed flaring activity up to the end of the observation. If the initial decay is indeed related to the prompt emission, the duration of the GRB would be about 550 s (assuming the trigger time of 16:57:13 UTC, GCN 38594). If we consider the X-ray long lasting emission being part of the prompt emission, GRB 241217A would qualify as an ultra-long GRB, as also suggested by the EP/WXT light curve (Zhou et al. GCN 38606), or potentially as a jetted TDE. Further X-ray observations are planned. The average spectrum of the X-ray emission can be well fit by an absorbed single power law model with a power law photon index of 1.38+/-0.05 and an NH value of 0.12+/-0.01 x 1e22 /cm2. Follow-up observations at other wavelengths are encouraged. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. MXT was developed jointly by CEA, CNES, University of Leicester, IJCLab and MPE. The SVOM point of contact for this burst is: Brunet Marius (marius.brunet@irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/38622. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...