Strange pattern on roof of my car

Strange pattern Yesterday before i go to sleep, i looked through the window and found strange circle on roof of my car. Day was very sunny and first i thought that something dark (like a leaf) fell on roof, heated it and melted snow. But edges was very sharp and it looked like accurate circle, next guess was that somebody forget something on my car or it just a prank. With these thoughts i fell asleep. At the morning i want to the car and found frozen water streams on the windshield and grounded battery. After that i remember that last sunday i tuned shock sensor and used lamp attached to roof inside the car. I remember that i swiched it off, but this lamp have strange complicated construction and i was not turned of it completely. The final surprise was that the car could not be opened with a remote control and  all locks on doors was blocked by dust (because i never used it before), but WD-40 saved the situation.