  The rapid variability of blazars in almost all wavelengths is now well
established. Two days of observations were conducted at the Palomar Observatory
during the nights of 25 and 26 February 1997 with the 5-meter Hale telescope,
in order to search for rapid variability in the near-infrared (NIR) bands J, H,
Ks for a selection of eight blazars. With the possible exception of 1156+295
(4C 29.45), no intraday or day-to-day variability was observed during these two
nights. However, for these eight blazars, we have measured the NIR luminosities
and spectral indices. It has recently been reported that the gamma-ray emission
is better correlated with the near-infrared luminosity than with the X-ray
luminosity. This correlation is suggested as a general property of blazars
because hot dust is the main source of soft photons which are scattered off the
relativistic jets of electrons to produce the gamma rays by inverse Compton
scattering. We thus used this relationship to estimate the gamma-ray
luminosity.
