Astronomy & Astrophysics

All Tables

Table 1: Summary of IDV observations of J 1128+5925. The table lists the observation dates (Col. 1), the radio telescopes (Col. 2, "E'' for Effelsberg, "U'' for Urumqi), the frequencies (Col. 3), the total observation time (Col. 4), and the mean time sampling for the flux measurements of J 1128+5925 (Col. 5). Letters shown in the last column (Col. 6) refer to the corresponding variability curve, shown in Fig. 4.
Table 2: Primary calibrators and their flux densities at the three observing frequencies.
Table 3: The variability parameters of J 1128+5925 measured by the Effelsberg telescope and with the Urumqi telescope between 2004 and 2006. The letters in Col. 1 refer to the subplots of Fig. 4. Column 2 shows the starting date of the observation, Col. 3 the observing frequency, Col. 4 the observing telescope ("E'' for Effelsberg, "U'' for Urumqi). In Col. 5 the modulation index of the non-variable secondary calibrator is displayed, in Col. 6 the number of flux-density measurements for J 1128+5925. The mean flux density, its standard deviation, the variability amplitude, and the modulation index of J 1128+5925 are given in Cols. 7-10, respectively. In Col. 11 the reduced $\chi ^2$ ( $\chi _{\rm r}^2$ ) is shown. In Cols. 12-14 the measured variability times-scales are given. They were derived directly from the light-curves (Col. 12), using structure functions (Col. 13), and autocorrelation functions (Col. 14). In some light-curves, the peaks and troughs are not well-defined. In these cases we do not give an error for $t_{\rm lc}$ and the time-scales are given in parenthesis in Col. 12.
Table 4: Fit parameters for the annual modulation models shown in Fig. 6. Column 1 show labels used for the different fit curves. Columns 2 and 3 give the velocity components of the screen in Right Ascension and Declination direction. Column 4 shows the scintillation length scale, Col. 5 the axial ratio, and Col. 6 the position angle of the scintillation pattern. In Col. 7 we give the reduced $\chi ^2$ for the fits. For details of calculation of $\chi ^2_{\rm r}$ see text.
Table 5: Lower limits to the screen distance (Col. 2) and upper limits to the source size (Col. 3). In the calculations we used the scattering length scale as derived from the annual modulation model, the frequency dependence of the source size, which was derived from the frequency dependence of the modulation index, and we assumed 2.70 GHz as the upper limit to the transition frequency between weak and strong scattering. In Col. 1, the letters refer to the different annual modulation curves, see Table 4 and Fig. 6. In Col. 4, for comparison, we list the Fresnel angle at 4.85 GHz at the distance of the screen. Column 5 gives the estimated scattering measure for a transition frequency of 2.70 GHz.