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GCN Circular 35935

X-ray transient EP240315a: Nanshan/HMT optical upper limit
2024-03-17T06:52:41Z (4 months ago)
Dong Xu at NAOC/CAS <>
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S.Q. Jiang, Z.P. Zhu, X. Liu, J. An, S.Y. Fu, T.H. Lu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report on behalf of a large collaboration:

We observed the field of EP240315a detected by Einstein Probe (EP, Zhang et al., GCN 35931) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. We obtained 30 x 90 s frames without any filter.

No uncatalogued optical transient is detected within or near the EP/WXT error circle, down to a limiting magnitude of r ~ 20.9 at a median time of 20.44 hr post-trigger, calibrated with the nearby PanSTAR field.

The previously reported ATLAS optical counterpart candidate, AT2024eju, (Srivastav et al., GCN 35932) is not present in the HMT co-added image, indicating that it has decayed significantly. Our non-detection is consistent with that from LT (Srivastav et al., GCN 35933). 
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