Logarithm of the water-production rate for different apparitions of comet 41P in 2001, 2006 and 2017 as a function of time to perihelion. Combi (2017) derived the production rates from hydrogen Lyman-α emission observed by the SWAN instrument onboard SOHO in 2001 (black circles) and 2006 (red squares). Our water-production rates (blue diamonds) were derived from the OH production rates using the relationship given in Cochran & Schleicher (1993). The water-production rates given in Bodewits et al. (2018) are derived from the Swift/UVOT observations of OH emissions (green triangles) and are in good agreement with the TRAPPIST ones.