Time is an important characteristic of the information you are looking at. In almost all social media outlets there is a time stamp indicating when the message was sent. This will tell you something about the possible location of the person sending the message as you might be able to determine if the source was actually present when an event occurred.
In this conversation, Pegah claims to have seen a celebrity football player at 1:02am, and that he had sunglasses on. Sara points out her inconsistency.
Check the time stamp on the message sent to you from the source. Is the time close to the time of the information you are verifying? If yes, the source may be a primary source or someone following information very closely. If no, the source may still be a primary source but did not have immediate access to communication means, or they are a secondary or tertiary source.