Access rss feed for private folders?

There is an rss function included in gallery 3. I can access to the rss link ( e.g the latest or a specific folder ) for public folders. I want to use this rss feed to import items into drupal 7 with feeds. For public folders this works fine, but if it is a private folder, the import fails.

My question - where do i have to do the authentication to access the rss feed. I can open the rss feed in the same browser, if I am a logged in user with the proper permissions. I can't access from a different browser.

It would be kind if someone can explain to me how to authenticate or use the rss feed links for private galleries.

Thanks katasun