■ [blazar] S5 0716+714 : detection of a flare
We update the data of S5 0716+714. We can see a flare clearly between JD=2454747 and 4760. Also the color V-J was blue when the object was brightening.
■ [blazar] PKS 0048-097 : Bright
The figure shows the light curve of the object in V band (red point) and the time variation of the V-J color (green point). The object has become bright since JD=2454757, and the magnitude of the object reached about 14.9 mag. In addition, the color has become blue. The feature is called as the "bluer-when-brighter".
■ [blazar] PKS 2155-304 : light curve & color
We report our observation of PKS 2155-304. The figure shows the light curve of the object in V band and V-J color variation. The object shows a fading trend but the color still remains blue.
■ [blazar] AO 0235+164 ; faded
We have continued to observe AO 0235+164. The figure shows the light curve of the object in V band. The magnitude of the flare in JD=2454755 was reached in about 15 mag. After the peak of the flare, the magnitude was faded to 15.7 mag in 6 days. The object is, however, still in the bright state.
■ [blazar] PKS 0048-097 : remain active
We started observation PKS 0048-097 on 2008 Oct. 2. The mag. of the object in V band is 15.2-15.7 during our 1-month observation. It has been recorded as 17.3 mag.(by SIMBAD). Once the object reached a maximum on Oct. 9. After that the object tended to become faint but it tend to become bright again in these 4 days.
We have observed 3C 371 since 7 July 2008. The figure shows the light curves of the object in V, J and Ks bands. The amplitudes of variations in V and Ks bands might be larger than those of J band. That behavior is mysterious if the optical-infrared emission is dominated by a single component of the synchrotron emission. The object tend to be bright.
■ [blazar] PKS 1749+096 : variation of color
The figure shows the light curve of PKS 1749+096 in V band and a V-J color. The color of the second flare is bluer than that of the first flare. In the recent 7 days, the magnitude of the object faded but the color is still blue.
As noticed by Dr. Yamaoka in vsnet-alert 10580, the black hole X-ray binary, V4641 Sgr is currently active in X-rays. The above figures show the light curves of our observation (the red points) and the model of the ellipsoidal modulation (the green lines) (Upper panel: 7 - 17 Oct, lower panel: 16 - 26 Aug). On 14 and 16 Oct, the object was ~0.1-0.15 mag brighter than its quiescent level, although it was on the quiescent ellipsoidal modulation on 9 Oct and in August. The object is, thus, active also in the optical regime.
On 15 Oct, it was rather close to its quiescent level, as can be seen in the upper figure. At that time, the object was in the secondary minimum of the ellipsoidal modulation. In that phase, the secondary star of V4641 Sgr can hide the active region in the accretion disk around the black hole. The relatively low level on 15 Oct may be due to the partial eclipse of the central active region.
■ [blazar] AO 0235+164 : Fermi and our data
The figure shows the light curves of AO 0235+164 in GeV gamma-ray region and V band. These light curves in both gamma-ray and optical regions are variable by a factor of four and sixteen. The optical variation is, hence, larger than the gamma-ray one. The gamma-ray and optical light curves seem not to show a clear positive correlation.
■ [blazar] PKS 2155-304 ; fading trend
PKS 2155-304 is the one of the brightest and famous blazars. We have observed the object since 9 Jul. 2008. The figure shows a light curve in V band and a V-J color variation. The magnitude of the object faded and the amplitude was about 0.7 mag.. There were some short flares which tended to be blue. The color has gradually become red except for the flares.
■ [blazar] PKS 0048-097 ; brightening
The figure shows the light curve of PKS 0048-097 in V band and the time series of the polarization degree in the same band. The object became bright, and the magnitude of the object reached about 15.3 mag. on 7 Oct. 2008 in V band. The object is usually at about 16 mag. in V band. It is now in a bright state. The average of the polarization degree was about 5 %. The polarization degree was variable.
We have been observed 3C 66A since 9 Jul. 2008. Although the magnitude of this object had gradually decreased until 19 Sep., the object have become bright. Atel #1755 also reported this behaviour. The V-J color became bluer when the object became bright. We continue to observe the object.