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The topology and polarization of subbeams associated with drifting subpulse emission of pulsar B0943+10 - VI. Analysis of an 8-hour GMRT observation

We report analysis of an 8 hr observation of PSR B0943+10 at 325 MHz performed at the Giant Metrewave Radio Telescope (GMRT) in India. B0943+10 is well known for displaying regular sub-pulse drifting and two emission modes. We investigate the modal behavior of B0943+10. By reconstructing an entire 'B' mode from two consecutive 'B' modes, we estimate that the pulsar spends roughly 7.5 hrs in the 'B' mode and about 2.2 hrs in the 'Q' mode, on average. Although the pulsar can switch modes within one pulse, the sub-pulse drift rate changes with a characteristic time of 1.2 hrs over the course of a 'B' mode. Under the subbeam carousel model we find the drift-rate changes are produced by a 10% increase in the average number of subbeams and a 16% increase in the carousel circulation time. We speculate that under the partially screened gap model the increase in circulation time should be related to a small increase in the neutron star surface temperature.