2. Radio data
The radio data presented here come from three principal sources, at frequencies of 4.85, 2.42 and 1.40 GHz. Characteristics of these data are given in Table 1.
Table 1. Details of the radio observations of RX J0852.0-4622. Note that the PMN survey data contain no information on scale-sizes of and larger. The rms noise is quoted per beam area.
First, 4.85-GHz data have been obtained from the Parkes-MIT-NRAO (PMN) survey images (Griffith & Wright 1993). These images were observed using the 64-m Parkes radio telescope, and have an angular resolution of approximately . Processing of the PMN observations has removed large-scale information () from the data. Nevertheless, the PMN images are a useful source of higher resolution information, and are often able to trace structures of large angular size through associated smaller-scale emission components (e.g. Duncan et al. 1997).
Second, 2.42-GHz data surrounding RX J0852.0-4622 have been observed as part of a larger survey presented by Duncan et al. (1995). These data have a resolution of and include linear polarisation information. Some results from these data pertaining to the Vela region have been presented by Duncan et al. (1996). These data were used by Combi et al. (1999) to make the radio detection of RX J0852.0-4622.
Third, 1.40-GHz observations of the region containing the remnant were obtained in 1996 September, as part of a larger survey of the Vela region at this frequency. Some of these data have already been used by other authors (e.g. Sault et al. 1999).
The observing procedure employed for these 1.40-GHz data was analogous to that used for the 2.42-GHz survey (Duncan et al. 1995). The telescope was scanned over a regularly-spaced coordinate grid, at a rate of per minute, until the region of interest had been completely covered. This procedure was then repeated, scanning the telescope in the orthogonal direction. Stokes-I, Q and U data were recorded. The source PKS B1934-638 was used as the primary gain calibrator for the observations. The flux density of this source was assumed to be 14.90 Jy at a frequency of 1.40 GHz. The source 3C138 was also observed, in order to calibrate the absolute polarisation position-angles. The intrinsic polarisation position-angle of 3C138 is (Tabara & Inoue 1980). After the calculation and subtraction of appropriate "baselevels" from each scan, each pair of orthogonally-scanned maps was combined.
© European Southern Observatory (ESO) 2000
Online publication: January 29, 2001