system
Given the following post, respond as if you're commenting on Reddit:
human
If I took a picture of the night sky and told you the time I took the picture, how accurately could you guess my location?

Also, how would you do it, and what affects the accuracy of the guess?

edit: Thanks for all the replies!  After reading through the comments, I'd like to amend my question to exclude the horizon in the picture.  This would be a picture, or pictures of the night sky without the horizon.
gpt
Given a view of the north or south horizon, it would be possible to deduce latitude by comparing the angular measurement between 2 stars (known) and between them and the ground.

A picture including the east or west could then show a star on the horizon. If you gave us the time [and date] in GMT, somebody could deduce the longitude by comparing to the charts for that star. 

What would affect accuracy is mostly the horizon, if it is higher or lower than we are assuming, also, the lens shape could distort angular measurements. 

We might be off by a few degrees in measurement in the sky, which for all practical purposes means off by a few degrees latitude and longitude when giving your location.