Brightness predictions for comets

The total magnitude m1 of a comet, generally defined today as the integrated brightness of the coma, is a concept with an evolving history that arguably began in the early-modern era with Isaac Newton (1687, see also Cohen et al. 1999), though this concept was not analysed in detail until late in the 19th century (cf. Green 1996a). The quantity m1 gives information about the activity of comets and for many comets it provides virtually the only information on such activity, as spectrophotometric or spectroscopic information is not available for most of the historic comets (or even for most of the modern-day fainter comets). While there has been some debate about how to link m1 data to modelling of sublimation and dust release from the cometary nucleus, there is a continuing effort at seeking correlations between m1 data and flux information gathered in specific bandpasses at both optical and non-optical wavelengths.