Shafaqna – The moon visibility map above shows that on 14 June 2018 the moon will be visible in some countries of the world by naked eye , but it will not be visible by the naked-eye in the UK and some other countries.
Please see the map, green areas are visible to the naked eye (A-easily, B-more difficult, C-after found with optical aid) however, the yellow D area is visible with telescopes:
With regard to determining the first day of Shawwal 1439, you should refer to your Marja’s fatwa as fatwas are different regarding whether moon visibility should be by naked eye or aided and also the required location of the visibility, whether it has to be in the location or country you live in or in another particular country.
According to astro.ukho.gov.uk the visibility of the New Crescent Moon (on 13, 14 and 15 June 2018) from selected locations in the UK, Mecca and Rabat are:
https://en.shafaqna.com/wp-content/uploads/2018/06/moon.jpg618800adminhttps://en.shafaqna.com/wp-content/uploads/2018/02/new-logo-s-2.pngadmin2018-06-10 16:29:012018-06-10 16:57:06Moon visibility map for 14 June 2018 (Thursday) UK / Globe