Online at the
Bundesarchiv, the nearest order of battle is for 22 June 1940 in file RL 2-III/707b. Screenshot attached: squares are aircraft, circles are pilots; solid shading = ready for operations, x = not ready.
The Stab JG 77 diary covering 21 June 1940 is Bundesarchiv file RL 10/301 but that doesn't cover what happened in the II. Gruppe, it just says "no special events".
The Western Front sitrep for 21 June 1940 is online here:
Russisch-deutsches Projekt zur Digitalisierung deutscher Dokumente in den Archiven der Russischen Föderation | Akte 96. Lageberichte West des Führungsstabes der Luftwaffe (1c).
On page 6 of that report (my translation): "Between 1600 and 1700 hours in the sea area west of Hardanger Fjord, one attack by British aircraft on one of our fleet units took place, directed in the first instance against the battleship
Scharnhorst. 3 Lockheed Husons and 4 Hampden-Herefords were shout down by the fighter units deployed. After being fired on, one Sunderland pulled away burning into the clouds. In addition six aircraft were shot down by ships' Flak."
If you scroll on to the bottom of page 11 of that report, there's a discussion of how to attack a Hampden and where its vulnerable points are.
The Bundesarchiv also has the log of the
Scharnhorst for April–September 1940 in file RM 134/179 which can be viewed online and downloaded. The entries for 21 June begin on page 351.