Context :

Aims : Using a counter-dispersed slitless spectroscopy technique , we detect and measure the line-of-sight velocities of 187 planetary nebulae ( PNe ) around one of the nearest cD galaxies , NGC 1399 , with FORS1 on the VLT .

Methods : We describe the method for identifying and classifying the emission-line sources and the procedure for computing their J2000 coordinates and velocities .
The number of PN detections and the errors in the velocity measurements ( 37 km s ^ { -1 } ) indicate that this technique is comparable to other methods , such as that described by Teodorescu et al .
( 2005 ) .

Results : We present the spatial distribution of the PNe and a basic analysis of their velocities .
The PN two-dimensional velocity field shows marginal rotation consistent with other studies .
We also find a low-velocity substructure in the halo and a flatter velocity-dispersion profile compared to previous observations that extends to \sim 400″ .
The detection of a low-velocity subcomponent underscores the importance of discrete velocity tracers for the detection of un-mixed components .

Conclusions : The new velocity-dispersion profile is in good agreement with revised velocity dispersions for the red globular clusters in NGC 1399 , using the data of Schuberth et al .
( 2009 ) .
The outer parts of this profile are consistent with one of the dynamical models of Kronawitter et al .
( 2000 ) , which corresponds to a circular velocity of \simeq 340 km s ^ { -1 } and a rescaled B-band mass-to-light ratio of \simeq 20 at 7 ’ radius .
These measurements trace the kinematics of the outer halo and disentangle the heterogenous populations in the Fornax Cluster core .
The new data set the stage for a revised dynamical model of the outer halo of NGC 1399 .