According to Facebook graph API we can request a user profile picture with this (example):
https://graph.facebook.com/1489686594/picture
Bu
Yeah, "Location" response header tell you the actual image URL.
However, if you use the picture as the user's profile image on your site, I recommend you to use "https://graph.facebook.com/:user_id/picture" style URL instead of actual image URL. Otherwise, your users will see lots of "not found" images, or outdated profile images in the future.
You just put "https://graph.facebook.com/:user_id/picture" as the "src" attribute of "img" tag. They browser gets the updated image of the user.
ps. I have such troubles on my site with Twitter & Yahoo! OpenID now..