Ground support for the $\gamma$-ray observatories by monitoring the 200
strongest flat-spectrum AGN at 22 and 37 GHz.


Ter\"asranta H.$^1$ 

$^1$Mets\"ahovi Radio Observatory, 02540 Kylm\"al\"a, Finland\newline


The monitoring of the brightest AGN with the Mets\"ahovi Radio telescope
has continued over 20 years. We have currently about 85 sources in our
primary source list, which should be observed monthly at 22 and 37 GHz.
For a better ground support for this decades space borne $\gamma$-ray and
millimeter observatories; INTEGRAL, AGILE, GLAST and PLANCK, we have
expanded the source list to about 200 sources. The source list now includes
all flat spectrum ($\alpha>-0.4$, from 5 to 22 GHz) Northern AGN which have
a flux greater than 0.5 Jy at 22 GHz on average. Also included in the list 
are the $\gamma$-ray AGN detected by EGRET north of declination -13 degrees.
The flat spectrum to higher frequencies, from 20 GHz upwards, seems to be
a dominant charasteristic in the $\gamma$-ray detected sources. Therefore
while looking for new candidates to $\gamma$-ray sources, special attention
should be put to their mm-wavelength properties.