2 The observation and reduction

There are 384 stars which are from FK5/FK4 Supp. in 12 fundamental groups. The observations of radio stars were placed in the reference group of stars. The residuals of the radio stars are calculated applying the corrections of astronomical time, latitude and zenith distance found from fundamental group observations. Then the mean values of the residuals of radio stars are calculated by weighted average.

Assuming $V_{\rm e}$ and $V_{\rm w}$ are the residuals reduced to the mean instrumental system after adding the group corrections of reference groups at both eastern and western transits, the position corrections of the radio stars are determined in right ascension and declination from double transits by the formulas:

$$\Delta\alpha = \frac{V_{\rm e} - V_{\rm w}}{30\cos\varphi_0\vert\sin A\vert},$$ (1)

and

$$\Delta\delta = -\frac{V_{\rm e} + V_{\rm w} -2K}{2\cos q},$$ (2)

where

$\varphi_0$ - the adopted value of latitude at the site of the instrument;

A - the azimuth of a star observed, measured eastwards from north;

q - the parallactic angle of a star as it transits the almucantar of the astrolabe.

We used the stars with $\vert\cos q\vert<0.2$ to calculate 2K by averaging

$$K =\frac{1}{2}(V_{\rm e} + V_{\rm w}),$$ (3)

and obtain $2K=0.018'' \pm0.003''$.