We analize the light curve of comet P/Halley resulting from 187 observations made by amateurs. We try to derive some constraints on the physical properties of the comet through the application of the semi-empirical photometric model (SEPM) developped by R.L. Newburn.

The m1 (Fig. 2) and V(1,0) light curves show a clear transition phase in the pre-perihelion apparition, between ~ 1.9 and ~ 1.2 A.U. which supports the division into 3 parts made by Hasegawa. It is remarkable to find that the light curve obtained by amateurs is so close to those obtained by experienced observers.

We derive an effective equivalent radius of β = 4.9 ± 0.8 (1σ) km, and a geometrical albedo of pυ = 0.06 ± 0.02 (1σ) using the method suggested by Delsemme and Rud.