Craft appeared as faint dot of light, flared to intense luminosity, dimmed back down, and departed at high speed

Stargazing at 10:30 pm local time, facing north, my attention was drawn to a faint light I saw traveling high in NE sky (about 70 [seventy] degrees).
The light appeared initially like a common satellite in terms of brightness and size as it approached from the east. Then, it slowed and seemed to descend, tracing out a path in the shape of the number 5. In other words, it slowed, continued to travel east-to-west, then dipped straight down, and then traced an arc (again, imagine the shape of a number 5).
As it traced the arc, it increased in brightness until about midway through the arc's completion, it was as bright as an approaching airliner's landing lights, whereupon it began to decrease in luminosity.
When the arc was completed, the light was back at its original luminosity. At this point, it accelerated in a straight path directly to the north and was gone in about five seconds.