Its the best site for photos. THE BEST! Otto is a U2 photo genius! [see Otto/RS photo thread]
If you're using photos for a class project and downloading them from his site, I would say just send him an email to let him know. He does have access to email while on the road. However, he does not have access to a scanner so any new pictures from the last leg of the tour are going to be up after its all over. It may be awhile to wait but it will be well worth it.
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"Things will not be the same in this city for us." -Bono, Dublin, February 1980