Radiation monitoring drones or UFO's?

I have been following all the news about the drones in NJ. I don't know if they are searching for a radioactive source of some kind. What I find quite puzzling is why they are doing this all at night and in the dark. If it were testing if the drones or searching for something then surely daylight would be considered an essential tool? From what I have seen and read they don't appear to be flying during the daytime at all. That's the strangest thing for me at the moment. Will just have to see where this goes.

With regards to detecting something it depends on two things; how active the source is (it's mass and type of radioactivity) and the shielding used. I'm not sure on the mass of weapons material needed for a nuclear missile, but it would probably fit in a suitcase. The whole warhead would not. Pu-240 is a alpha emitter and thus the alpha particles can be easily blocked, but it decays into U-236, which wouldn't be as easily blocked. I'm not suggesting it is a nuclear warhead at all, I'm simply using that as an example. How far could it be detected? That depends on many factors, the mass of the material, shielding, other background interference, the type of detection used. Someone that knew what they were doing could probably shield a source enough for it to not be noticed, but the shielding mass may be more than one could carry easily, but may be OK in a vehicle. The answer really is akin to 'how long is a piece of string?'

I noticed the site was going slow a couple of days ago. Dan had a look last night and the map was getting hammered. Dan disabled some of the tile rendering on the map that has cut a bit of slack, but not much. We didn't know if this was some attack or not. I described it to Dan 'as though many people had the map on display, and were constantly refreshing the page.' I guess now we know why there is an influx of traffic and looks like the little Pi can't handle all the requests and traffic.   The crazy thing is there is no need to refresh the map, the readings update dynamically. I may put a notice on the map page later today when I have time.

As I have heard this possible and supposed radioactive source was potentially in a suitcase, I asked chatGPT for some details.

The mass of the nuclear material in a Trident I SLBM warhead would be roughly 4-5kg. It is mainly Pu-240 and decays to U-236. This would require some 10cm of lead shielding, and some 10cm of polyethylene (hydrogen-rich material) around the lead. The radius of the outer shell of polyethylene would be around 30cm, making the entire diameter of the shell 60cm. So imagine a 60cm sphere, 10cm thisk, lined with another 10cm thick sphere of lead, and then the nuclear material in the center. That total mass would weigh around 400kg. So certainly too heavy for a suitcase. Unshielded it would be very detectable, completely shielded it wouldn't be detectable at all. It could also be anywhere in between.

If these drones were looking for a radioactive source of some kind, why look only at night? Radiation knows no time limits. I have thought long and hard about the drones flying only at night, and it makes no sense. If this were drone testing, daylight would be preferable. If these were drone taxis, daylight would be preferable. In every usage case point I can think, daylight would be preferable. So I think an equally important question to 'what are they looking for or doing?' is 'why only at night?'

Edit: I was incorrect about the Plutonium, it would be Pu-239, not 240.

I have also attached the brief ChatGPT conversation to this post, and here is a link if anyone wants:  https://chatgpt.com/share/67613a63-eaa0-800a-88ec-2ae4349a1f35