12p 20230722 223658 ndj

This image was taken 21.15 hours after the previous one and the coma has expanded from 26 to 36 arcsec diameter. That is a change in radius of 0.24 arcsec/hour. The current distance of 12P is 3.5 au which is 530 million km which is around 2,500 km per arcsec so the expansion velocity looks to be around 160 m/s. The total magnitude is constant in an expanding aperture which is what would be expected from a large impulsive release of material into the coma.