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 Siriusin broad daylight’(Applied
Optics 54, B1-B7 (2015),
downloadable from this website.