3.7 micron saturates at 312 K, saturated pixel is assigned -0.05 K

First image is a night time image, but can see transition into day. High clouds reflected by the sun in the night time part. Other two images are daytime, one being of the day following night time image.

Good band arithmetic choice is 03.70 image - 12.00 image, but can also see clouds. Therefore, create another condition to remove pixels in 12.00 image lower than a threshold cold temperature over clouds.

After applying algorithm to subset, apply to whole image, and see how many false fires are detected!

See burnt areas in the centre of the ring of fires in the daytime image.