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The magnetic Cataclysmic Variable (mCV) V1432 Aql (RX 1940.1-1025) belongs tothe four-member subclass of near-synchronous polars with a slightnon-synchronism (<2 %) between the spin period of the white dwarf and thebinary period. In these systems the accretion geometry changes periodicallywith phase of the beat cycle. We present the application of a dipole accretionmodel for near-synchronous systems developed by Geckeler & Staubert (1997a) toextended optical and X-ray data. We detect a significant secular change of thewhite dwarf spin period in V1432 Aql of dP_spin/dt = -5.4 (+3.7/-3.2) 10-9 s/sfrom the optical data set alone. This corresponds to a synchronization timescale tau_sync = 199 (+441/-75) yr, comparable to the time scale of 170 yr forV1500 Cyg. The synchronization time scale in V1432 Aql is in excellentagreement with the theoretical prediction from the dominating magnetic torquein near-synchronous systems. We also present period analyses of optical CCDphotometry and RXTE X-ray data, which argue against the existence of a 4000 speriod and an interpretation of V1432 Aql as an intermediate polar. The dipoleaccretion model also allows to constrain the relevant parameters of theaccretion geometry in this system: the optical data allow an estimate of thedimensionless parameter (R_t0'/R_wd)1/2 sin(beta) = 3.6 (+2.7/-1.1), with alower limit for the threading radius of R_t0' > 10 R_wd (68% confidence).

The near-synchronous polar V1432 Aql (RX J1940.1–1025): Accretion geometry and synchronization time scale