I directly respond to the points raised by the referee below.

> We thank you for submitting a contribution of high quality to the proceedings of the 
> HEPRO-VIII conference. Your contribution has now been reviewed by a referee, who 
> recommends its publication in PoS after you have taken into consideration the following > remarks/corrections: 

> - in the abstract and at the beginning of Sec.3: "AGN blazars" -> "blazars"

I removed "AGN" at several places where it does not affect clarity for the
non-specialist reader.

> - page 6: "no contemporary data in the X-ray rang were available" -> "... range ..."

Corrected.

> - finally, the referee suggests that you add a few references to the work of various research groups to reflect the community's efforts in this area of research. 

11 new references from other groups have been added at various places.

I hope that the manuscript is now suitable for publication.