TITLE:   GCN CIRCULAR
NUMBER:  36271
SUBJECT: LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
DATE:    24/04/24 03:54:34 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

X. Liu, Z.P. Zhu, S.Q. Jiang, J. An, S.Y. Fu, D. Xu (NAOC), J.P.U. Fynbo (DAWN/NBI), N. Koivisto, A. A. Djupvik (NOT) report: 

We observed the location of the Swift/XRT source 61 (labelled S240422ed_X61) at coordinates RA, Dec = 120.3245d, -28.1765d (J2000; https://gcn.gsfc.nasa.gov/other/S240422ed.counterpart), which is within the error region of the LIGO/Virgo/KAGRA event S240422ed (GCN 36236, GCN 36240). Observations started at 20:41:38.400 UT on 2024-04-23, i.e., ~ 23.11 hr after the LVK trigger time, and a series of frames were obtained in J-/H-/K- bands.

Preliminary data analysis shows that there is no credible source detected at the XRT position in the stacked J-band image, down to a limiting magnitude of J ~ 18 mag, calibrated with the 2MASS field.