EP250101a
GCN Circular 38785
Subject
EP250101a: Xinglong optical upper limit
Date
2025-01-03T03:28:53Z (5 months ago)
From
Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) <xinglong@nao.cas.cn>
Via
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Yu-Zhang(NAOC), Junjie-Jin(NAOC), Haiyang-Mu(NAOC), Yuguang-Sun(NAOC), Zheng-Jie (NAOC), Zhou-Fan(NAOC), Hong-Wu(NAOC) report on behalf of a large collaboration:
Following the detection of EP250101a by EP-WXT (Y. F. Liang et al., GCN 38778), we observed the field of EP250101a using the 80cm telescope at Xinglong Observatory, NAOC. We obtained 11x400s clear-band frames with a median time of 2025-01-03T01:08:55 i.e., 43 hr after the EP trigger. No uncatalogued optical transient is detected in the stacked images within the 3.2 arcmin EP/WXT error circle (Y. F. Liang et al., GCN 38778), down to 5-sigma limiting magnitudes of clear ~ 20.1, calibrated with Pan-STARRS sources in the field. Also, there is no apparent brightening for the catalogued sources within the error circle.
GCN Circular 38801
Subject
EP250101a: Liverpool Telescope optical upper limit
Date
2025-01-03T16:39:44Z (5 months ago)
From
A. Bochenek at Liverpool John Moores University <a.m.bochenek@2023.ljmu.ac.uk>
Via
Web form
A. Bochenek and D. A. Perley (LJMU) report:
We observed the field of the fast X-ray transient EP250101a (Liang et al., GCN 38778) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 6x200s exposures in the SDSS i’ filter starting at 2025-01-02 22:39:43 UT, approximately 1.7 days after the trigger. Four of the images had to be discarded due to autoguider issues.
We do not detect any new sources in the EP/WXT confidence region (Liang et al., GCN 38778). The 3-sigma limiting magnitude on the stacked images is i > 21.6 mag, calculated using the nearby PanSTARRS secondary standards as reference. The photometry was not corrected for extinction.