I was sitting on the southwest edge of the baseball field behind westerly creek elementary in denver's stapleton neighborhood. i looked up from the game (north) because i saw a white teardrop shaped object climbing above the school's roofline as it flew from east to west. the object flew past the western edge of the school and continued to climb to maybe 1500 feet. at first i thought that it must be a drone because there were no visible propellors or strobe. i quickly realized that there was no easy way to ascertain size or distance, it was half the size of the plastic ball shaped head of one of those color push pins at arms length. the object rapidly circled a little bit closer toward me (south) as it climbed to perhaps 2000 feet and hovered. in full disclosure, i am an avid ufo nut, however i can only recall one other time in my life that i've seen an object that i couldn't explain. this is also a highly populated area and directly in line with the dia flight path. i thought that perhaps it could be a helicopter at a greater distance than i realized, but when you look on a google map i don't see any hospitals in close enough proximity to the flight path to explain the apparent size of the object. it is possible that someone could have flown a drone from central park in stapleton, but as you're about to hear that becomes doubtful. the sighting was brief, no more than 90 seconds and probably more like a minute. i knew that the object would be too small to resolve adequately on my cell phone, there was simply no point in recording something that might show up as a pixel in size when zoomed at best. i believe that the object may have rapidly swung from west to east at a distance of no more than a half a fist in width at arm's length. the object quickly arced to the west and climbing in altitude headed north. as the object approached the cloud ceiling (it seemed to be 3k-5k ft) i definitely saw it glint off the sun and it was just a bright white teardrop kind of shape. i had fought the urge to ask others around me if they saw what i was seeing and i swore that if it came back i would point it out. it did not return, it appeared to continue to fly due north of me at a high rate of speed quickly diminishing into a speck before it disappeared. in retrospect, it is possible that the object was faintly glowing or perhaps it had a faint dark halo around it. the luminance, speed and lack of visible aircraft attributes really caught my eye and i remember mentally searching for a rational explanation of what i was seeing. not ten minutes later i saw a guy walking around the softball game with an slr and a massive telephoto lens attachment. if i'd seen him during the sighting we would have either had a confirmed helicopter or intriguing images from a daylight sighting with traceable provenance.