TITLE: GCN CIRCULAR NUMBER: 38600 SUBJECT: GRB 241217A : SVOM/VT optical afterglow detection DATE: 24/12/17 23:42:59 GMT FROM: SVOM_group svomgroup@bao.ac.cn
Y. L. Qiu, H. L. Li, L. P. Xin (NAOC), D. B. Malesani (DAWN/NBI and Radboud Univ.), S. D. Vergani (Obs.Paris), J. T. Palmerio (CEA), M. Brunet (IRAP), D. Turpin (CEA),C. Wu, X. H. Han, J. Wang, W. J. Xie, H. B. Cai, Y. Xu, Y. J. Xiao, P. P. Zhang, J. S. Deng, L. Lan, X. M. Lu, R. S. Zhang (NAOC), J. Zhang, L. J. Dan, G. Y. Zou, C. J. Wang, Y. F. Du, C. Huang (XIOPM), H. Zhou (PMO)，R. Z. Li (YNAO)
report on behalf of the SVOM team:
GRB 241217A (Brunet et al., GCN circular 38594) was observed by on-board SVOM/VT after the automatic slew of the satellite. The VT conducted observations in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously.
With the downlinked X band data an uncatalogued optical source was detected in stacked images in both VT_B and VT_R bands within the error box of SVOM/ECLAIRs (6.8 arcmin radius at 90% C.L.), SVOM/MXT (25 arcsec radius at 90% C.L.), compared to the DESI Dr10 catalog.
The source is located at RA, Dec = 84.1513626, -25.2970374, which is equivalent to:
RA (J2000) : 05:36:36.327
Dec (J2000): -25:17:49.33
with an uncertainty of 0.5 arcsec.
This source overlaps a faint extended source visible in archival DESI images of the field.
This position is consistent with the X-ray counterpart position of Swift/XRT reported by Williams et al. (GCN 38599).
The light curve of the counterpart in VT_R decayed from 240 s to 500 s after the burst and then a re-brightening occurred with a maximum at around 1000 s and then re-decayed. The magnitude was VT_B=22.4, VT_R=21.4 mag in AB magnitude about 300 seconds after the trigger.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC),CAS.
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