thanks for the the measurement.
There is indeed a peak near 6200 A. In that region are some H2O+ lines. Hale-Bopp has been photographed with a 6199A +/- 7nm filter: https://agupubs.onli....1029/97GL03704
But my camera is blind in that region.
I derived some values from my pictures. Raw frames where only dark-current and flat-field corrected, stacked, downscaled by factor two an 5x5 pixel median filtered, i.e. 10x10 pixel noise filtered. (No background correction)
Brightness was measured on 12 coordinates in 3 groups. Each group (red, green, blue frames in the image below) consists in 4 coordinates which lay approximately on a line. The outer points where used for background measuring. Between the outer points background is approximated linearly. The frame depicts the area where the values where median filtered.
Here here the background corrected results of the inner points (#2 left inner frame which seems to be bluer in the image):
Red frame #2: red: 1.2 blue: 31.9
Red frame #3: red: 20.9 blue: 62.2
Green frame #2: red: 4.0 blue: 43,4
Green frame #3: red: 25.3 blue: 90,3
Blue frame #2: red: 4.1 blue: 47.0
Blue frame #4: red: 34.3 blue: 107.0
Units are e- per pixel an per second. Btw, background flux was 2903 e-/s for blue and 1350 e-/s for red.
So the red component is quite significant and not distributed equally in the ion tail. (Was not sure about that because the shape of the reddish component can also come from erroneous black level calibration)