GCN Circular 45873
EP261007b: J-band upper limit by SYSU 80cm infrared telescope
From: unknown
Issued: 2026-10-09 12:29 UTC
Type: X-ray Transient

Jing-Kai Sun, Jin-Ji Li, Zhong-Nan Dong, Jia-Qi Lin, Pu Lin, Yun Shi, Hao-Nan Yang, Rui-Chen Gao, Hao-Ran Zhang, P H Thomas Tam, Rong-Feng Shen, Bin Ma (Sun Yat-sen University) report on behalf of the SYSU 80cm infrared telescope team:

We observed the field of the X-ray transient EP261007b (Wen et al., GCN 45847) using the Sun Yat-sen University (SYSU) 80cm infrared telescope. Our observations were carried out on 2026 Oct 08 from 17:09 to 18:10 UT, 26.1 hours after the EP/WXT trigger, using stacked images in the J band (180 x 20 s, 1hr total exposure).

We do not detect any new source within the FXT localization (Wen et al., GCN 45847), nor at the position of the variable source reported by Quirola-Vasquez et al. (GCN 45864) at RA, Dec = 23:45:22.41, +11:20:25.8 (J2000), in our stacked J-band image. We obtain a 5-sigma upper limit of J ~ 20.0 mag (Vega).

Our non-detection is consistent with the non-detections reported by Ma et al. (GCN 45849), Zhang et al. (GCN 45860), Mohan et al. (GCN 45861), Shi et al. (GCN 45862), and Quirola-Vasquez et al. (GCN 45864).

The SYSU 80 cm infrared telescope is operated and managed by the Department of Astronomy, Sun Yat-sen University.

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