The rocket, launched at 2000 hours yesterday, was the last of the three sounding rocket launches intended to study the dynamics of the equatorial ionosphere during the occurrence of ``Spread-F phenomena'', an ISRO release said here today. It carried a total payload of about 127 kg to a predetermined altitude of 424 km.

The first rocket was launched on April 19, 1998. After evaluation of the data from this first launch, the second flight was conducted last week, the release said. All the three launches in the series were carried out under a commercial arrangement between ISRO and the German Space Agency, DLR.

The experiment was conducted during the occurrence of ``Spead-F phenomena'' specially during the period of equinox.

The scientific payloadswhich the rocket carried were, Resonance Cone payload of AWT, Freiburg; Radio beacon experiment of German Research Space Establishment (DLR); impedance probe and langmuir probe payloads developed by University of Kiel and precision magnetometer developed by Danish scientists. The Polish space centre, Warsaw, developed the antenna deployment systems for the radio beacon experiments.