NOT ABSOLUTELY SURE IT IS NOT A FORM OF "CHROMATIC ABERATION". INVESTIGATING.

Shot taken at 36x with addon of teleconverter Olympus TCON-14B(1.4x) and -17(1.7x) stacked and ND400 filter.
?BLUE/Violet FLASH?: ON DISAPPEARING EDGE. [0.3]PERSONAL RANKING ON A SCALE OF 0.0~6.0.
THIS WAS NOT VIEWED WITH THE EYES PRIMARILY BECAUSE OF THE DISK BRIGHTNESS BUT WAS RECORDED BY THE CAMERA.
WX AT VIEW LOCATION. ___________________________________ (see 4_06-10 sunset for total view).
HORIZON ESTIMATED AT 15 MILES - MT. MONADNOCK HEIGHT AT 'POINT OF CONTACT" (est. 2200 ft elevation) FROM AN OUTLOOK AT 1300 FEET.