GCN Circular 40170
Subject
GRB 250419A: SVOM/VT optical bright counterpart confirmation
Date
2025-04-19T05:05:51Z (5 days ago)
From
Liping Xin at NAOC, SVOM <xlp@nao.cas.cn>
Via
Web form
L. P. Xin, Y. L. Qiu, C. Wu, H. L. Li., Z. H. Yao, Y. N. Ma, X. H. Han, H. B. Cai,J.Y. Wei (NAOC), J. T. Palmerio (CEA), B.-T. Wang (YNAO, CAS), Y.H. Cheng (SWIFAR,YNU), W. J. Xie(NAOC), report on behalf of SVOM/VT team:
After the trigger by SVOM/ECLAIRs at 2025-04-19T02:29:32 UTC (Tb), SVOM performed an automatic slew on the burst. SVOM/VT began observing the field at 45.26 min after the SVOM trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
An uncatalogued and bright source, compared to DESI catalog, is found by automatic ground pipeline based on VHF data within the error box of SVOM/ECLAIRs (Wang et al. GCN 40168) at ra=202.40533, dec=7.04106 (J2000), corresponding to:
RA (J2000) = 13:29:37.28
Dec (J2000) = +07:02:27.8
with an uncertainty of 0.5 arcsec.
The source is detected in both VT_R and VT_B in the third VT observing sequence, the magnitudes are given below:
MidTime min | exposure time (s) | mag(AB) | mag err | band
47.767 | 6x50 | 17.790| 0.02 | VT_R
47.767 | 6x50 | 18.220| 0.01 | VT_B
The position and the brightness are consistent with the report (López et al., GCN 40169).
Given the VT color of the counterpart, it might be a low redshift gamma-ray burst.
The Space-based multi-band astronomical 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.