UFO Sighting in Massachusetts on 2018-06-17 00:00:00 - Flashing light in sky

I walked out of my house at approximately 11 am. as i was walking in my yard and into my driveway, i looked up into the sky and witnessed a flashing light. i observed it for like about 15 minutes and then decided to pull out my iphone to video record the flashing light. i was able to zoom in very well and recorded 3 short videos of approximately 30-40 seconds. the whole event lasted for about 30-40 minutes. the whole entire time the unknown object was moving north at a very slow pace. then i had to leave to go run an errand. when i returned home, the unknown was not present.