Near infrared monitoring of a sample of blazars with the Carlos Sanchez Telescope.

We present results of a program of near infrared monitoring of a sample of blazars and miniblazars observed during 1990 and 1991 with the Carlos Sanchez Telescope, in Teide Observatory, Tenerife. All of the objects in the sample show blazar activity during the course of the observations. Several of the objects in the sample have been monitored for rapid variations on timescales of a few hours; only one of them has not, to date, shown such activity. Markarian 421, Markarian 501, 3C273, and AO 0235+164 show evidence of possible color variations, although only in Markarian 501 and AO 0235+164 are these color changes beyond doubt. One object, 3C345, unlike other blazars, shows a flatter spectrum when fainter, confirming previously published results.

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