>>1928087 (lb)
I use a screencap tool for Linux called Shutter that automatically names the file with a timestamp in a format specified by me. Unfortunately automatic Zulu timestamping is not an option; my timestamps will be MDT or MST. It has a built-in quick editor so one can annotate easily without using high-end graphics tools. A REG # has to be typed manually when saving, but that is do-able.
Getting organized here...
Do you have a spreadsheet list of target REG #s? Manual note-taking system has already gotten overwhelmed by the number of planes we are tracking.