I'm a police officer and was working an overtime shift 11-7 at Taunton State hosital due to a B&E the night before. I was stationed alongside the facilities power plant when at approx. 12:30 AM I observed a redish glowing object in the western sky that caught my attention. As the object aproached I was watching to see the norrmal Nav/ ID stobe lights on aircraft. As the object got closer I could still not see any apparent nav/strobe lights. Elsewhere in the sky ther were other aircraft and normal nav/strobe lights could be observed. Finding it odd that I could not see any navigation or ID safety stobe lights, I shut off my cruiser & stepped out. The object passed almost directly overhead my position at aprox. 2500 feet. aeared to be right belon the cloud ceiling. I could not make out any shape except for a glowing kind of oval / egg shape that pulsed slowley. The object passed overhead completely silently. There was no engine sounds, prop sounds, rotor sounds and even when it was directly overhead did I ever observe any normal navigation lights associated with aircraft. The object continued on past my position in an easterly heading until it passed out of sight. The entire event lasted no more then 2-3 min. I have to say that I'm 52 yrs of age. and a aircraft enthusiest, being very familer with known aircraft today, and until this morning I have never observed anythng that I could not identify as a recognizable, known aircraft. be it fixed, wing or rotory winged. This one left me baffled, and I could only say that for me it was a true unidentifed flying object. Thought you might be interestedThanks for readingJim R