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GCN Circular 37278

Subject
GRB 240825A: 1.6m Mephisto multi-band detection
Date
2024-08-25T18:03:57Z (2 months ago)
From
Brajesh Kumar at SWIFAR, YNU <brajesh@ynu.edu.cn>
Via
Web form
Jinghua Zhang (SWIFAR, YNU), Guowang Du (SWIFAR, YNU), Helong Guo (SWIFAR, YNU), Brajesh Kumar (SWIFAR, YNU), Tao Wang (SWIFAR, YNU), Zhenfei Qin (SWIFAR, YNU), Yicheng Jin (SWIFAR, YNU), Xingzhu Zou (SWIFAR, YNU), Yu Pan (SWIFAR, YNU), Xinlei Chen (SWIFAR, YNU), Yuan Fang (SWIFAR, YNU), Xuhui Han (NAOC), Pinpin Zhang (NAOC), Liping Xin (NAOC), Chao Wu (NAOC),  Yuanpei Yang (SWIFAR, YNU), Xinzhong Er (SWIFAR, YNU), Xiangkun Liu (SWIFAR, YNU), Xiaowei Liu (SWIFAR, YNU) report on behalf of Mephisto Team:

Simultaneous multi-band photometric observations of the Swift GRB 240825A (Gupta et al., GCN 37274Not found
 
 
), Fermi (Fermi GBM team, GCN 37273Not found
 
 
) was performed with 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. Mephisto was triggered immediately after the notice and the observations were started at (UTC) 2024-08-25 15:55:07 in moderate sky conditions. Multiple frames in uvgriz -bands were acquired. The OT (Gupta et al., GCN 37274Not found
 
 
, Jiang et al., GCN 37275Not found
 
 
, Dutton et al., GCN 37276Not found
 
 
, Odeh et al., 37277) is clearly detected in each frame. The preliminary magnitudes in initial frames are below: 

Time (2024-08-25 UT)  Filter   Exp (sec)  Mag (AB)
15:55:07                v         180     16.73 +- 0.01
15:55:07                r          60     14.46 +- 0.01
15:55:07                z         120     13.61 +-  0.01
16:08:10                u         180     19.15 +- 0.09
16:08:10                g          60     17.49 +- 0.03
16:08:10                i         120     16.42 +- 0.01

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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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