Monitoring EXO 2030+375 with RXTE

We propose regular monitoring observations of the 42-s accreting X-ray pulsar EXO 2030+375 to measure the spin frequency, pulsed flux, and orbital phase of the outburst peak. X-ray monitoring will be accompanied by optical/IR monitoring of the Be star. Our scientific objectives are to investigate if the pattern of global spin-up followed by spin-down observed with BATSE repeats and if it is related to the 10-15 yr precession cycle of the Be disk. PCA observations in 2003 showed that the pulsar is again spinning up and ASM observations indicated that the outbursts are brightening, suggesting that the pattern is repeating. We predict that our cycle 10 observations will monitor EXO 2030+375 as its spin state reverses if the pattern repeats, and in a bright, spin-up state if it does not.