# A New Online Service for the Validation of Multi-GNSS Orbits Using SLR
## 3 Results
### Assessment of the Orbit Quality
Station characteristics included in a title in order: place, detector type, max repetition rate (Hz), timer type, pulse width (ps), max energy (m). The quality and quantity of SLR observations made by various stations are unquestionably different. Observations collected by particular stations equipped with different detector types should be individually analyzed. The problem of individual station behavior should lead to attempts of modeling the systematic biases and residual dependencies as an aim to improve both the overall SLR dataset as well as the overall geometry of observations, which is one of the main issues of the past, current, and future SLR network. Only a certain proportion of the current dataset of SLR residuals to GNSS satellites seems to be clearly unbiased and provides clear information about the orbit quality. Lack of knowledge and consciousness about the particular stations' performance and the dependency arising from, e.g., the type of the detector, may lead to misjudgment of the whole orbit quality or single satellite behavior as the range biases can achieve values of several centimeters. Since 6 August 2017, CODE orbits include the antenna thrust and albedo models for Galileo and QZSS satellites, in addition to previously included GPS and GLONASS models. The first visible differences in SLR residuals caused by this change are presented in Table 4. The month preceding the change was compared with the month following the change. Despite a limited time span, the improvement is clearly visible (see Figure 8). The mean offset decreased mostly for all Galileo satellites. The offsets have changed from \(-38\) to \(0\), from \(-44\) to \(-1\), and from \(-57\) to \(-8\) mm, whereas standard deviations are changed from \(40\) to \(20\), from \(18\) to \(23\), and from \(30\) to \(21\) mm for Galileo FOC, FOC\({}^{*}\) and IOV, respectively (see Figure 8). The improvement of the core statistics for GLONASS-M and K1 is smaller than for Galileo satellites but also noticeable (see Table 4). The increase of the standard deviation for GLONASS-K1 is caused by the individual problems of the satellite at the end of August 2017. Some anomalous positive biases of +30 mm are also visible for GLONASS-M+. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**System**} & \multirow{2}{*}{**Type**} & \multicolumn{3}{c}{**July 2017**} & \multicolumn{3}{c}{**August 2017**} \\ \cline{3-8}  & & **AVG** & **STD** & **OBS** & **AVG** & **STD** & **OBS** \\ \hline \multirow{3}{*}{GALILEO} & FOC*(ext.) & \(-38\) & \(40\) & \(1592\) & \(0\) & \(20\) & \(1880\) \\  & FOC*(ext.) & \(-44\) & \(18\) & \(354\) & \(-1\) & \(23\) & \(361\) \\  & IOV & \(-57\) & \(30\) & \(609\) & \(-8\) & \(21\) & \(714\) \\ \hline \multirow{3}{*}{GLONASS} & K1 & \(-18\) & \(16\) & \(545\) & \(8\) & \(61\) & \(560\) \\  & M & \(-19\) & \(26\) & \(3486\) & \(-9\) & \(25\) & \(3643\) \\ \cline{1-1}  & M+ & \(12\) & \(23\) & \(288\) & \(30\) & \(16\) & \(343\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: SLR residual offset (AVG) and standard deviations (STD) for the period 1 July 2017–31 August 2017. Values are in mm. Abbreviations used: AVG, average; STD, standard deviation; OBS, number of observations. Figure 7: Relationship between local time on the laser station and both average SLR residuals and number of generated observations on selected laser stations; Dataset from October 2015–July 2017, consisted of only SLR residuals related to GLONASS-M satellites with uncoated LRA. Abbreviations used: No. Obs., number of observations.