You can contact 911 but they most likely won't believe you and ignore your call.
I was once a 911 dispatcher. Since there is no law against being a blob of light in the sky, there was nothing for 911 to do. So contacting 911 is useless. I suggest contacting your local airport.
I am assuming you mean "alien spacecraft". Aliens are Immigration's problem. I suggest contacting the Federal Immigration people, as it seems that local laws mirroring Federal Laws are unconstitutional, but somehow the Federal laws aren't.
We have not yet made contact with any aliens.
We do not know. We have not made contact with any aliens.
We do not know. We have not made contact with any aliens.
We do not know. We have not made contact with any aliens.
We do not know. We have not made contact with any aliens.
We do not know. We have not made contact with any aliens.
We have not made contact with any space aliens.
We have not yet made contact with any aliens.
We do not know. We have not made contact with any aliens.
Aliens are not known to actually exist, so your question is unanswerable.
The aliens tried to avoid human contact.
We do not know. We have not made contact with any aliens.