A dear friend from Switzerland sent me this question: “Do you know when and where this photo was taken and are there more from this jam?”
Answer: There are no other photos known to exist of this jam, or at least not in my collection.
The answer to the date can befound in Hendrix 1969: Day By Day, page 146-149:
18 and 19 March: Jimi jams with Lonnie Youngblood and his backing band the Blood Brothers at Small’s Paradise in Harlem, New York City.
More on these jams here: