As has been mentioned, it
is possible for a normal CMOS-type camera to see the
short wavelength radiation from
very hot items that aren't hot enough to be
incandescent and thus be visible to the naked eye. Here's a backyard example.
I had been burning some wood waste in my garden brazier earlier in the day, only leaving it after the flames had died down. Some hours later, well after dark, I was surprised to see it apparently glowing brightly on my security camera. It's just a cheap visible / near-IR auto-switch camera, nothing special, but it saw the heat from the brazier. Virtually nothing was visible to the naked eye; it wasn't even glowing dim-red. This implies it was cooler than the
Draper Point (~525°C, 977°F); as has been noted elsewhere, anything over about 400°C begins to emit a small amount of energy in the wavelengths that can be detected by silicon sensors (ie about 1.1µm or 1100nm).