The Herald of the Night of Burning Stars appears to be an astrolabe composed entirely of mummified animal parts — paws, legs, digits, and the like. It is considered sacred to the mummies of the Radioactive Desert, as well as any who worship Nyarlathotep, as it is believed to be an artifact of the eventual ascendance of the Crawling Chaos.
The Herald requires a short invocation chant to activate (although some claim it can also be activated by destroying it, as well). When activated, the user can summon a meteor swarm, as per the spell. The Herald of the Night of Burning Stars only works once, becoming inert thereafter.
(For anybody wanting D&D 4e rules, activating the Herald allows the user to make an area burst within 20 attack at +18 vs. Reflex. The Herald causes 5d6 fire damage (half on a miss). This is a consumable object, and only works once.)
Persistent rumor places the Herald of the Night of Burning Stars within the armory of a crashed Space Alien vessel somewhere in hex 1804 on the Carcosa map. There is another rumor that a party of adventurers from Sigil accidentally activated and destroyed the device, but who knows if either of those rumors are true?