2. Observations

The observations were performed between August and October 1984 and August and September 1991. We used at 102 MHz the Large Phased Array Radio Telescope of the Lebedev Physical Institute at Pushchino (Russia), at 230, 408, 610, and 1380 MHz the 76-m Lowell radio telescope of the Jodrell Bank Radio Observatory (UK) and at 1400, 4700 and 10500 MHz the 100-m radio telescope of the Max-Planck-Institut für Radioastronomie at Effelsberg (Germany). Additional measurements with higher resolution were made in 1994/96 at the Large Phased Array (Kuzmin & Losovsky 1996).

Two circular polarizations were received at all frequencies, except at 102 MHz, where the telescope accepted linear polarization. The distorting effect of the polarization at 102 MHz on the pulse profile was smoothed out by interstellar Faraday rotation across the receiver band and by averaging several observing sessions. The resulting profiles are expected to represent nearly total intensity, depending on the number of days used for the mean profiles.

The sampling interval was selected individually for each pulsar depending on the pulse period and the dispersion smearing. At Effelsberg the sampling interval was normally choosen to be 1/1024-th of the observing period. The influence of dispersion was removed by use of filter banks. The main characteristics of the receivers and the dispersion smearing for are listed in Table 1 (click here). The amount of smearing due to the sampling interval and due to dispersion is indicated for each pulsar in Fig. 2 (click here) by horizontal bars.

Between 62 and 7600 single pulses were added synchronously to obtain the integrated profiles. The master clocks of all observatories were synchronized to better than 0.1 ms against the respective national main time standards.

 

Frequency Bandwidth DM = 1 pc cm^-3

(GHz) (kHz) (ms)

0.102 0.154 0.039

0.23 0.085

0.408 0.015

0.61 0.0045

1.38 1000 0.0032

1.4 0.002 4.7

10.5 500 MHz 0.0036