Gerald Kelleher wrote:
When it is sunset it is also star rise and when is star set is also
sunrise with just that short period of dawn and twilight when it is neither.

Completely wrong! Sirius is visible long after sunrise and before sunset

http://adsabs.harvard.edu/full/1984JBAA...94..221H

I knew Colin and he told me he eventually found he was not the first to see
Sirius in the daylight. An English female astronomer had reported this in
the 19th century.