In our case, Chile has two different time zones (Continental and Easter Island, with 2 hours of difference). Of course, 99,9% of the population is concentrated in one time zone, but we decided in order to avoid any problem, to put in the bylaws of the contest that we are going to use the Continental time zone (UTC-4 at the beggining, UTC-3 at the end of the contest) just to be sure.

2012/8/24 Tomasz W. Kozłowski <odder.wiki@gmail.com>
Hi Yaroslav,
the problem we face here is that there are no technical means to use
this scheme.

Firstly, there is only one UploadCampaign for the US (same for Canada,
the Netherlands, and Russia) - and secondly, the current CentralNotice
and GeoNotice systems do not (truly) enable us to set up different
campaigns for respective administrative divisions of a country (in
this case, mainly the US and Canada).

And just like you wrote, it would be a nightmare to track
post-deadlines pictures: how would you tell if a user uploaded a
picture from California or from New York? What would matter: the
location of the object (based on geo-coordinates and GPS data, for
example) or the real-life location of the user at the time of upload?
;-))

I believe that besides the countries you mentioned - Canada, France,
the Netherlands, Russia and the US - also Mexico uses different time
zones. (Any countries I missed?) I would love to hear from people from
those countries what they think as to what should be done here.

--
Tomasz W. Kozłowski
a.k.a. [[user:odder]]