A very close Venus-Regulus conjunction (2 Oct 23 UT, minimum separation 5’) can be used to explore the naked-eye visibility of Regulus during dawn. In Europe, the Venus-star separation in the early morning of 3 Oct is 20’. The proposal is to determine the moment when the visibility of Regulus is lost in the sky background. This project is a follow-up from the previous attempt (2012), described in the appendix of my paper ‘Naked eye visibility of Sirius in broad daylight’ in broad daylight’ (Applied Optics 54, B1-B7 (2015), downloadable from this website.

Kommentar auf eine Behauptung das Merkur bei etwa halber Beleuchtung maximale Helligkeit habe.