given by Patterson (1998, private communication):\

$ HJD ~~ \, 2\,444\,782.9168(2) + 0.014519035(2)\,E +$

$ 7.002(7)\,10^{-13}\,E^{2} -  1.556(2)\,10^{-18}\, 
E^{3}$                        (1)

The UV rotational pulses lag the optical by $\Delta \Phi_{\rm rot} =0.186$. Such colour effect will be discussed in more detail in sect.5.

Furthermore, the time of coherence between spin and beat modulations is found to be $HJD_{\rm co}$ = 2449971.2335 $\pm$ 0.0070 in both UV and optical. Throughout this paper the Patterson et al.’s orbital ephemeris will be used but $\Phi_{\rm orb}$ = 0.0 will refer to the orbital maximum. Hence, phase coherence occurs at $\Phi_{\rm orb} = 0.90\pm$0.03. i.e. close to the orbital maximum, whilst in 1988 and 1990 it was found close to the orbital minimum (Osborne & Mukai 1989; Paper1). Such phase changes are not uncommon for FOAqr (Semeniuk & Kaluzny 1988; Hellier et al. 1990).

The rotational modulation
=========================

UV continuum, zero-order light, and UV emission line fluxes as well as their V/R ratios have been folded in 56 phase bins along $\rm P_{spin}$. The spin pulses, pre-whitened from all other frequency variations, are shown in Fig.3 together with the optical B band pulses folded in 28 phase bins. A strong colour effect is observed 