Hatena::Groupkanatatmp

KANATA ObsLog

2009-04-30

[] PKS 1502+106 : Bright

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PKS 1502+106 is one of the brightest blazar in gamma-ray region. The figure shows the light curve in V band and the V-J color variation. The object has recently been bright since JD 2454850. The V-J color was about 2.4. Compared with the color during JD 2454700, the object has become redder.

[] SN 2009an: The light curve has already been a "Co decay" phase.

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We have performed B,V,Rc,Ic-band photometric observations for normal Type Ia SN 2009an. We showed the light curve in the figure. The all band magnitudes are decreasing according to a radioacitve decay of Co^56. We will continue the observation for this object.

[] SN 2009dc : Update

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The light curve of SN 2009dc was updated.

2009-04-29

[] GRS 1915+105 : H-band light curve

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We have started the 2009-season observation of a black hole X-ray binary GRS 1915+105 in near-infrared bands. The figure shows the H-band light curve from 2008(red dots) to 2009(blue dots). Our recent observations indicates that the object is in the low state in the near-infrared regime.

[] V1280 Sco : light curve update

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The optical fading trend continues accompanied with the reddening.

[] SN 2009dc : Update

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We update the light curve of peculiar Type Ia SN 2009dc. The I-band luminosity reached maximum light later than bluer band luminosity. Normally, the I-band first maximum come to earlier than the other bluer band maximum.

2009-04-28

[] BL Lacertae ; Data update

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The object had highly polarization degrees in last season. The polarization degree of the object in V band reached about 30 %. The figure shows the light curve and temporal variation of the polarization degree in V band. The brightness and the polarization degree was also highly variable.

[] S5 0716+714 ; brighten

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The figure shows the light curve of the object in V band and the V-J color variation. The object has recently been brightened and reached about V~13.5. The V-J color became bluer when the object was brightened.

[] Type II SN 2009dd : Observations Start

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We have started multicolor photometric observations of Type II SN 2009dd. We showed the light curve in the figure. The muticolor photometry shows that the object is highly reddened by host galactic dust. The light curve of this object seems flat. Such a behavior of the light curve indicated that the similar to that of Type II plateau. If SN 2009dd is Type II plateau supernova, we will conduct a polarimetric observations using HOWPol in order to research a shape of ejecta inner than hydrogen shell.

[] SN 2009dc : reached maximum light

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The brightness of this object seems to reach around maximum light. We will research how decline rate the object decreasing the luminosity in B,V,Rc,Ic-band, and whether the light curve shapes should be (or not) used as luminosity indicator for the peculiar bight Type Ia supernovae.

[] J1509-21: fading continues

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The fading and reddening trends continue. The object will probably return to the apparent quiescent state within a few days.

2009-04-27

[] OJ 287 : faded

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The figure shows the light curve in V band and V-J color variation of OJ 287. The object has recently been faded. The color became bluer. The object, thus, shows the feature of the redder-when-brighter trend.

[] SN 2009dc : Update

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We update the light curve of the peculiar Type Ia SN 2009dc. The light curve shows that the light curve around maximum light looks broad. We will continue the observations.

2009-04-24

[] SN 2009dc : Update

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We update the light curve of SN 2009dc. The brightness of this object reached around maximum light.

2009-04-23

[] SN 2009dc : Update

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We continued the photometric observations of peculiar Type Ia SN 2009dc. The figure shows the BVRcIc light curve.

[] J1509-21: update

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The monotonic fading and reddening trends continue.

2009-04-22

[] OJ 287 : Rising the Polarization Degree

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The figure shows the light curve of the object (red point) and the temporal variation of the polarization degree (blue point) in V band. The object had recently faded, and the polarization degree in V band rose. The polarization degree reached about 35 %.

[] SN 2009dc : Still Rising !!

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We performed photometric observations of peculiar Type Ia SN 2009dc. The preliminary results show that the brightness of SN 2009dc is still rising! We will continue more dense observations.

[] PKS 1510-089 : faded and bluered

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PKS 1510-089 had brightened since JD 2454900. The object reached about V~14.9. The object showed the feature of redder-when-brighter trend, which was redder when the object was bright. The object was faded at JD 2454940.

2009-04-21

[] J1509-21: fading trend continues

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The object keeps decaying with the reddening trend.

[][] HT Cam: high-speed photometry

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HT Cam is an intermediate polar, occationally showing a quite short (<1 day) outburst, like dwarf novae. An outburst of the object was reported on 17 Apr. We performed high-speed photometry with a time-resolution of 1 sec. Preliminary light curves are shown in the above figure. The figure also includes our result during the last outburst in Feb. 2008. On 17 Apr, the object was almost at maximum of the outburst. We can see possible 200-300-s periodic modulations seem to be rapidly evolving. Compared with the light curve on 7 Feb. 2008, the light curve on 17 Apr. 2009 might exhibit shorter time-scale variations. On 18 Apr, longer time-scale modulations were apparently dominant. No signal of white-dwarf pluses (514 s) was detected in all light curves we obtained.

[] J1509-21: high-speed photometry

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We performed high-speed photometry of this unidentified object on 18 Apr. The above light curve is an example of our 2-hour run. The time-resolution of the observation is 1 sec. We calculated the power spectrum using the light curve. No periodic variation was found. Short-term (2 sec - 100 sec) variations were weak. The light curve is apparently dominated by a white noise.

2009-04-20

[] Peculiar Type Ia SN 2009dc : Still rising !

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We have started the B,V,Rc,Ic-band photometric obserrvations of Type Ia SN 2009dc since Apr 17. The spectra of SN 2009dc exhibits the much low line velocity of SiII6355 and the profile was similar to that of SN 2006gz (Hicken et al. 2007, Ap.J. 669, L17), which was reported in CBET 1768 by Harutyunyan et al. We derived preliminarily apparent multicolor magnitudes of SN 2009dc, using the USNO-catalogue magnitudes of a comparison star around SN. The preliminary light curve shows the still rising to maximum light in all band. We will observe this object.

2009-04-17

[] J1509-21: fading continues with a reddening trend

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The nature of the object is still unknown. It keeps fading, with a clear reddening trend. The average fading rate remains almost constant at 0.05 mag/day. The raddening rate of V-J can be calculated to be +0.17/day. At quiescence, the object is V=11.229 (Tycho-2), J=10.536(2MASS), and hence, V-J=0.693. If the fading and reddening rates are constant, the object returned to the quiescent level within two weeks.

2009-04-15

[] ASAS J150946-2147.7 (J1509-21): gradual fading & no rapid fluctuation

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The outburst of an unidentified object, ASAS J150946-2147.7 (J1509-21), was reported on 6 Apr. We started monitoring of the object on 9 Apr. The object showed small (<0.1 mag), but clear modulations with time-scale of hours. It is now gradually fading with an average rate of ~0.05 mag/day. We also performed high speed photometry on 11 Apr, while no significant rapid variation (10 - 1000 sec) was seen.

2009-04-13

[] J1028-08: the rapid fading stopped

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The rapid fading apparently stopped before it reached the quiescent level. The figure shows the light curve of J1028-08. The red and green symbols denote photometric points and their nightly averaged points, respectively. According to the USNO B1.0 catalog, the object is R~18.9 at quiescence. The object, hence, now remains at a state 1-mag brighter than the quiescence. It may be a sign of possible rebrightening events.

2009-04-10

[] J1028-08: rapid fading

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Our last night observation showed that the suspected V485-Cen like object, J1028-08, has just entered a rapid fading stage from the superoutburst. Note that EI Psc, a possibly similar system, experienced a rebrightening after superoutburst.

2009-04-09

[] SN 2009an : Secondary maximum in I-band

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We update the light curve of Type Ia SN 2009an. The secondary maximum day of SN 2009an is estimated as around 24 days after B-band maximum, which suggests that SN 2009an categorized to normal SNe Ia (Branch et al.(1993)). The secondary maximum of I-band magnitude would be thought to be luminosity indicator, though there are a small uncertainty of maximum day. In order to determine absolute magnitude, we require to derive the more reliable parameter using B-band light curve. We will continue the observations.

2009-04-03

[] Type IIP SNe 2008ij and 2008in have just come in the rapidly decreasing luminosity phase

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figure(a) : Light curve of SN 2008ij

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figure(b) : Light curve of SN 2008in

We show the light curves of two Type IIP supernovae (SNe IIP) 2008ij and 2008in in figure(a) and figure(b), respectively. The "TRI" and "HOW" mean that the data was obtained using TRISPEC and HOWPol, respectively. The two SNe has begun to rapidly decrease the luminosity, and the color of two SNe rapidly become red. The outer hydrogen layer of SNe IIP expanded and became optically thin. The spectral might show that the Balmer series of hydrogen lines weaken.

[] J1028-08 : humps with a very short period, confirmed

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OT J102842.9-081927 (J1028-08) was discovered by the Catalina Sky Survey on 31 March 2009. .

Due to the detection of possible superhumps with a quite short period (0.0381~d), the object is suspected to be a rare object, such as V485 Cen and EI Psc, or AM CVn stars (double-white dwarf system) (vsnet-alert 11149).

We performed time-series photometric observations of J1028-08 with KANATA last night (2 Apr). We confirmed the humps whose period is roughly consistent with the reported one. We found that the V-J color is quite blue (V-J~-0.6). The V-J color is usually between -0.2 and 0.2 in normal dwarf novae in superoutburst. In our past observations, CR Boo, an AM CVn star, exhibited a similar color during its superoutburst.

Although the S/N of our J-band data is low, phase-averaged light curves suggest that the hump amplitude is larger in V-band than that in J-band. The temperature of the hump component is probably higher than that of an underlying stationary component.

2009-04-01

[] PKS 1510-089 : Brightening

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Top figure shows the light curve in V band and V-J color variation of the object. The object has brightened since JD 2454900 and V-J color has become redder. Bottom figure shows the light curve in V band and temporal variations of the polarization degree in V and J band. Polarization degree in J band has always been higher than that in V band.

[] V1280 Sco : The light curve

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V1280 Sco is a classical nova which formed dust shell in the early phase of its eruption. The optical flux have recovered since autumn 2007 from V~17 to 11 due to the termination of the dust condensation. After the recovery, fluxes in V and J gradually increased for a year. Our recent V- and J-band light curves show that the brightness of the nova slightly decrease. This might indicate that the oncet of the "final decline" of V1280 Sco due to stop of the Hydrogen burning on the white dwarf.