The Morning Glory's ATP is determined by this formula: ATP = 500 + (.beat time / 4)
Now, the interesting thing is this... when you're online, .beat time is universal. That is, everyone has the same .beat time no matter where they are in the world. The .beat time is kept on the PSO servers and is sent to the clients when they connect. However, when you play offline, the .beat time is determined by your local system settings. For whatever reason, they decided that (offline) 8:00am = 000 beats.
Incidentally, to get the most out of my Morning Glory in an online game, I have to play around 3:00pm local time. So I guess mine is an Afternoon Glory. ;p
Kind of a neat idea for a weapon... but if it were me, I would have made the ATP rise and fall smoothly (like the sun?) instead of falling off abruptly when you go from 999 to 000 beats. I guess ST didn't want to mess with Sine functions.

Whee-hoo!!