What does it add to a masterpiece when astronomy can tell you the exact day it was made?

Astrophysical simulations suggest Van Gogh's The Starry Night was painted at dawn on 22 July 1889.

• A lot: it ties the painting to reality
• An interesting detail, but it changes nothing about the painting
• It takes the mystery out of the work
• I don't buy it, Van Gogh painted from imagination