Abstract: | Based on four previous studies with standard-candle quasars and using the correct formula for the luminosity distance, we obtain an improved determination of the deceleration parameter, q0 = +2.07. From the new catalog of quasars, we find the statistical relation and hence the mean quasar luminosity or and its rates of change and . Finally, we discuss the question whether there is a Malmquist effect in our sample and the question of the dichotomy of published q0-values. |