4 Conclusion

We have observed flux densities of 53 extragalactic radio sources with the Effelsberg 100-m telescope in the frequency range from 1.4 GHz to 32 GHz around the time of detection by EGRET on board CGRO and afterwards until the end of 1995 or the beginning of 1996. Nearly 2500 individual measurements have been made. The results are available in electronic form.

The radio database will be helpful to clarify the relation of the $\gamma$-ray variability to the radio variability. First studies by Mücke et al. (1996, 1997) indicate that the correlation of the light curves is rather complex and a statistical analysis needs to take into account the coarse sampling and limited dynamic range of the EGRET data.

Acknowledgements

We thank the Effelsberg telescope operators for qualified support.