Cosmography: Supernovae Union2, Baryon Acoustic Oscillation, observational Hubble data and Gamma ray bursts

In this Letter, a parametrization describing the kinematical state of the universe via cosmographic approach is considered, where the minimum input is the assumption of the cosmological principle, i.e. the Friedmann-Robertson-Walker metric. A distinguished feature is that the result does not depend on any gravity theory and dark energy models. As a result, a series of cosmographic parameters (deceleration parameter q0, jerk parameter j0 and snap parameter s0) are constrained from the cosmic observations which include type Ia supernovae (SN) Union2, the Baryon Acoustic Oscillation (BAO), the observational Hubble data (OHD), the high redshift Gamma ray bursts (GRBs). By using Markov Chain Monte Carlo (MCMC) method, we find the best fit values of cosmographic parameters in 1σ regions: H0=74.299−4.287+4.932, q0=−0.386−0.618+0.655, j0=−4.925−7.297+6.658 and s0=−26.404−9.097+20.964 which are improved remarkably. The values of q0 and j0 are consistent with flat ΛCDM model in 1σ region. But the value of s0 of flat ΛCDM model will go beyond the 1σ region.