We carried out a one-night optical V and near-infrared JHK monitoring observation of the least luminous Seyfert 1 galaxy , NGC4395 , on 2004 May 1 , and detected for the first time the intraday flux variations in the J and H bands , while such variation was not clearly seen for the K band .
The detected J and H variations are synchronized with the flux variation in the V band , which indicates that the intraday-variable component of near-infrared continuum emission of the NGC4395 nucleus is an extension of power-law continuum emission to the near-infrared and originates in an outer region of the central accretion disk .
On the other hand , from our regular program of long-term optical BVI and near-infrared JHK monitoring observation of NGC4395 from 2004 February 12 until 2005 January 22 , we found large flux variations in all the bands on time scales of days to months .
The optical BVI variations are almost synchronized with each other , but not completely with the near-infrared JHK variations .
The color temperature of the near-infrared variable component is estimated to be T = 1320 \sim 1710 K , in agreement with thermal emission from hot dust tori in active galactic nuclei ( AGNs ) .
We therefore conclude that the near-infrared variation consists of two components having different time scales , so that a small K -flux variation on a time scale of a few hours would possibly be veiled by large variation of thermal dust emission on a time scale of days .