V354 Cephei

The SIMBAD astronomical portal prefers to restrict that usage to AT Persei and has devised a different unique acronym for V354 Cephei.

[16] The Gaia Early Data Release 3 parallax is 0.2161±0.0388 mas, implying a larger distance.

Both Gaia results carry significant statistical margin of error, as well as indicators that the astrometric excess noise is far beyond acceptable levels so that the parallax should be considered unreliable.

Despite it, larger sizes and luminosities have been published for few other galactic red supergiants, such as VV Cephei A and the peculiar star VY Canis Majoris at 1,200–1,900 R☉ and more than 3,000 R☉.

[3][5] Other more recent published data assumes the smaller Gaia distance, and hence derives lower luminosities.