Context : Massive stars are important for the chemical enrichment of the universe .
Since internal mixing processes influence their lives , it is very important to place constraints on the corresponding physical parameters , such as core overshooting and the internal rotation profile , so as to calibrate their stellar structure and evolution models .
Although asteroseismology has been shown to be able to deliver the most precise constraints so far , the number of detailed seismic studies delivering quantitative results is limited .

Aims : Our goal is to extend this limited sample with an in-depth case study and provide a well-constrained set of asteroseismic parameters , contributing to the ongoing mapping efforts of the instability strips of the \beta Cep and slowly pulsating B ( SPB ) stars .

Methods : We derived fundamental parameters from high-resolution spectra using spectral synthesis techniques .
We used custom masks to obtain optimal light curves from the original pixel level data from the Kepler satellite .
We used standard time-series analysis tools to construct a set of significant pulsation modes that provide the basis for the seismic analysis carried out afterwards .

Results : We find that KIC 10526294 is a cool SPB star , one of the slowest rotators ever found .
Despite this , the length of Kepler observations is sufficient to resolve narrow rotationally split multiplets for each of its nineteen quasi-equally spaced dipole modes .
The number of detected consecutive ( in radial order ) dipole modes in this series is higher than ever before .
The observed amount of splitting shows an increasing trend towards longer periods , which – largely independent of the seismically calibrated stellar models – points towards a non-rigid internal rotation profile .
From the average splitting we deduce a rotation period of \sim 188 \mathrm { days } .
From seismic modelling , we find that the star is young with a central hydrogen mass fraction X _ { c } > 0.64 ; it has a core overshooting \alpha _ { ov } \leq 0.15 .

Conclusions :