  A novel FPGA based online tracking algorithm for helix track reconstruction
in a solenoidal field, developed for the PANDA spectrometer, is described.
Employing the Straw Tube Tracker detector with 4636 straw tubes, the algorithm
includes a complex track finder, and a track fitter. Implemented in VHDL, the
algorithm is tested on a Xilinx Virtex-4 FX60 FPGA chip with different types of
events, at different event rates. A processing time of 7 $\mu$s per event for
an average of 6 charged tracks is obtained. The momentum resolution is about
3\% (4\%) for $p_t$ ($p_z$) at 1 GeV/c. Comparing to the algorithm running on a
CPU chip (single core Intel Xeon E5520 at 2.26 GHz), an improvement of 3 orders
of magnitude in processing time is obtained. The algorithm can handle severe
overlapping of events which are typical for interaction rates above 10 MHz.
