TITLE: GCN CIRCULAR NUMBER: 40731 SUBJECT: sb25061207: Mephisto optical upper limits DATE: 25/06/15 03:55:24 GMT FROM: Brajesh Kumar at SWIFAR, YNU brajesh@ynu.edu.cn
Ziwei Li, Guowang Du, Haipeng Lei, Jianhui Lian, Haoyang He, Xingzhu Zou, Yu Pan, Xinlei Chen, Xufeng Zhu, Helong Guo, Tao Wang, Yuan Fang, Jinghua Zhang, Dezi Liu, Chenxu Liu, Shiyan Zhong, Edoardo Lagioia, Brajesh Kumar, Yuanpei Yang, Xiangkun Liu, Xiaowei Liu (all SWIFAR, YNU) report on behalf of the Mephisto Team:
We conducted simultaneous multi-band photometric observations of sb25061207 detected by SVOM/ECLAIRs (Zhang et al., GCN 40697) with the Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University, located at the Lijiang Observatory. Simultaneous u, g and v, r band observations of the field were initiated at 15:52:39 UTC on 2025-06-12 (~5.42 hours after the trigger) and three exposures of 300 seconds were acquired. In the stack images, no credible source was detected at the position of SVOM/VT (Li et al., GCN 40707), Swift/XRT (Evans et al., GCN 40711) and EP-FXT (Song et al., GCN 40718). The preliminary 3-sigma upper limits are listed below which are consistent with SVOM/COLIBRÍ (FM-GFT) (Becerra et. al., GCN 40723).
| UT Start |T-T0 (hr)|Band| EXP(s) |Lim-mag (AB) |2025-06-12T15:52:39| 5.42 | u | 300.0*3 | >21.24 |2025-06-12T16:10:13| 5.71 | v | 300.0*3 | >21.31 |2025-06-12T15:52:38| 5.42 | g | 300.0*3 | >21.60 |2025-06-12T16:10:12| 5.71 | r | 300.0*3 | >21.83
---------------------------------------------------------- Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6-m 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. ----------------------------------------------------------
View this GCN Circular online at https://gcn.nasa.gov/circulars/40731. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...