GCN Circular 37830
Subject
GRB 241018A/sb24101802: Mephisto optical upper limit
Date
2024-10-20T04:01:28Z (4 days ago)
From
Brajesh Kumar at SWIFAR, YNU <brajesh@ynu.edu.cn>
Via
Web form
Dezi Liu (SWIFAR, YNU), Jinghua Zhang (SWIFAR, YNU), Guowang Du (SWIFAR, YNU), Brajesh Kumar (SWIFAR, YNU), Zhijian Zhang (SWIFAR, YNU), Yule Wang (SWIFAR, YNU), Xinlei Chen (SWIFAR, YNU), Yu Pan (SWIFAR, YNU), Xingzhu Zou (SWIFAR, YNU), Yuanpei Yang (SWIFAR, YNU), Yehao Cheng (SWIFAR, YNU), Yuan Fang (SWIFAR, YNU), Xuhui Han (NAOC), Pinpin Zhang (NAOC), Liping Xin (NAOC), Chao Wu (NAOC), Xiangkun Liu (SWIFAR, YNU), Xiaowei Liu (SWIFAR, YNU) report on behalf of the Mephisto Team:
The field of SVOM GRB 241018A (Atteia et al., GCN 37812; Maggi et al., GCN 37814) was observed with the 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. Several uvgriz-band images were acquired in moderate sky conditions starting from 20:19:53 2024-10-18 UT (~8.4 hrs after SVOM/Eclairs trigger). At the GRB location, no new candidate (Qiu et al., GCN 37819; GCN 37825; Malesani et al., GCN 37821, Osborne et al., GCN 37823) was detected in the stacked images, consistent with Turpin et al. (GCN 37818), Ferro et al. (GCN 37822), Song et al., (GCN 37824), Mohan et al. (GCN 37825), Pankov et al. (GCN 37827) and Fernandez-Garcia et al. (GCN 37828). The 3-sigma upper limits are the following:
Mid-Time (UT) Band Total-Exp (s) Lim-mag (AB)
2024-10-18T20:33:07 u 180s x 2 >21.07
2024-10-18T20:31:59 v 180s x 2 >21.18
2024-10-18T20:33:04 g 50s x 6 >21.28
2024-10-18T20:31:56 r 50s x 6 >21.53
2024-10-18T20:33:04 i 79s x 4 >20.73
2024-10-18T20:31:56 z 79s x 4 >20.13
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Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. It provides real-time, high-quality colors of stellar objects. The on-site telescope assemblage and commissioning were carried out in September 2022. The first light in all three channels was achieved on 2023 December 21.
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