Failing to see Halley's comet one last time

Except for the gibbous moon, conditions are fine. I search the sky beneath Sagittarius, and then in broader sweeps. Far, dim stars wink in the field glasses. No comet. Beneath clusters of lights, distant towns sleep, dreaming of planting and unicorns. Moonlight flashes on the river below like a whirl of fireflies. Through the glasses, it fills the eyes, transmuting disappointment, by sleight of sight, into the ores of perception, promises kept -- how many of them. And, comet, as you withdraw in your obscure integrity, racing back out through the orbits of our system, you too kept your appointment, shyly but without ambiguity, like this cardinal now just waking, in the dark bushes, whistling its readiness for dawn.