Broadband r photometry (circles) of comet 2I/Borisov versus time from perihelion. The left vertical axis gives the magnitude, m, calibrated to the PS1-r system. The data are also converted to the cometary Afρ parameter and scaled by the phase function to a phase angle of 0° (squares). These values are given on the right vertical axis. The photometry shown in this figure is available as the data behind the figure.

(The data used to create this figure are available in the online article.)

(The data used to create this figure are available.)