TITLE:   GCN CIRCULAR
NUMBER:  45833
SUBJECT: EP261006a: NOT spectroscopy of a blue continuum
DATE:    26/10/07 12:40:15 GMT
FROM:    sqjiang at NAOC <sqjiang@bao.ac.cn>

S.Q. Jiang, D. Xu, J. An (NAOC), L. Lei, S.Y. Fu (HUST), L.B. He, X. Liu, Z.P. Zhu (NAOC), J.P.U. Fynbo (DAWN/NBI), E. Georgiou, A.S. Maartensson (NOT) report:

We performed the spectroscopy of the nucleus of the galaxy, Gaia DR3 2587044864659595392 (Hughes et al. 2022) with a photometric redshift of 0.184 (Duncan et al. 2022), which is within the EP-FXT error circle of EP261006a (Lao, et al., GCN 45826), using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 04:39:42 UT on 2026-10-07, i.e., 10.83 hr after the EP trigger, and 2 x 1200 s exposures were obtained, covering the wavelength range of ~ 3600 - 9200 AA.

The whole spectrum shows a clear blue continuum, without any prominent absorption or emission feature. The spectrum is different from the red one of the galaxy, which is close to an elliptical E0 type.

The spectral difference shows that the optical counterpart of EP261006a is at or very close to the nucleus of the galaxy, as reported in Eyles-Ferris et al. (GCN 45831).

The blue continuum spectrum would be consistent with an early transient such as TDE, FBOT, and so on (e.g., similar to EP260806a).

Further observations are planned.