SIMBAD references

We present multiwavelength analyses of an active optical transient AT2021fxu which shows the appearance of previously absent broad emission lines in a recent optical spectrum, suggesting a Changing-look Active Galactic Nucleus (AGN). During the spectral transition, the brightness in the individual photometric bands increased up to ≈0.6 in the optical bands and up to ≈1.1 mag in the UV bands. The brightening was accompanied by a blueward shift of the optical spectrum. AT2021fxu shows high X-ray (0.3-10 keV) flux variability before and after the outburst, with the average X-ray flux increasing by a factor of ≈2 post-outburst. However, the X-ray spectral shape remains roughly the same, with no significant change in the line-of-sight column density. AT2021fxu's overall properties are consistent with an accretion-rate-driven transition from a Type-II to a Type-1 AGN.