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GCN Circular 36320

LIGO/Virgo/KAGRA S240422ed: BOOTES-4/MET Optical Upper Limits for EP240426a
2024-04-26T16:03:13Z (3 months ago)
Dingrong Xiong at Yunnan Observatories of CAS, China <>
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D. R. Xiong, J. M. Bai, J. R. Mao, Y. F. Fan, C. J. Wang, Y. X. Xin, X. H. Zhao (Yunnan Observatories of CAS), E. Fernandez-Garcia, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, S.-Y. Wu and A. J. Castro-Tirado (IAA-CSIC, Granada), C. J. Perez del Pulgar (UMA) on behalf of the BOOTES team report:

A possible X-ray counterpart candidate of S240422ed (The LIGO-Virgo-KAGRA Collaboration, GCN 36236) EP240426a was found by EP-FXT (GCN 36313). 

We observed the EP240426awith R.A. = 121.8567 deg, DEC = -29.4609 deg, and did not found any optical counterpart within an uncertainty of 10 arcsec in radius compared to the PanSTARRS DR1 image. The upper limits of magnitudes (without being corrected for Galactic extinction) are given as follows. 

UT (start) | 3 sigma Upper Limit (error) | Exposure Time | Filter 


24-04-26 13:37:00 | 19.31 (0.02) | 60*10s | Clear 


The Burst Optical Observer and Transient Exploring System (BOOTES, is a completed world-wide network of robotic telescopes led at IAA-CSIC (Spain) which aims at following-up transients and other astrophysical sources in the sky for which the first station was installed in 1998 (Castro-Tirado et al. 1999). The fourth station of the BOOTES Network, BOOTES-4/MET, is located at the Lijiang Observatory of the Yunnan Observatories of China (Xiong et al. 2020). See also Hu et al. (2021). We acknowledge the support of BOOTES-4 technical staffs. ==================================================================
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