We update the light curve of SN 2010db. The color of this object is very red comparing to that seen in a typical supernova. Adding to the photometry of R and I bands, we also present the z'+Y-band light curve. The z'-band luminosity support that the color index is very high.
■ [dwarf nova] J2138+26: gradually fading
After the rapid fading stopped, the object is now gradually fading. The V-J color index is ~1.2, close to that observed in GW Lib just after its superoutburst. J2138+26 is now very red.
We have started the photometric observations of SN 2010dn. SN 2010dn was discovered of 17.5 mag in NGC 3184 on May 31.5 by K. Itagaki (CBET 2299). The photometric points seem to be increased as a supernova in the pre-maximum light. Alternatively, in CBET 2300, the spectroscopy was performed by Vinko et al.(2010), and the object was identified as a luminous blue variable (LBV) from the narrow H-alpha emission line and no broadened absorption features. we will continue the observations of this object.
■ [dwarf nova] J2138+26: a rapid fading stopped
J2138+26 is a new WZ Sge-type dwarf nova, discovered by Dae-Am Yi on May 7 (CBET 2273). The superoutburst entered a rapid fading stage on May 30 (vsnet-alert 12013). The object is suggested to be similar to GW Lib, another WZ Sge star outbursting in 2007, in terms of a low inclination angle and apparent brightness.
We have monitored this object with standard optical and near-infrared imaging and high-speed photometry with a time-resolution of 1 sec. The upper figure shows the V and J-band light curves we obtained. The V-J color during the superoutburst is quite similar to that observed in GW Lib (V-J~-0.2 -- +0.1). The rapid fading was confirmed in our observation on 31 May. At the same time, the V-J color increased to ~0.8, which is also analogous to GW Lib at the same phase. The lower figure shows the result of our high-speed photometry on 31 May. The rapid fading trend seems to be stopped, and small humps with an amplitude of ~0.1 mag can be seen. In the case of GW Lib, the rapid fading was not stopped like J2138+26, and continued until it reached V~15 and V-J~1.5.
The termination of the rapid fading implies that the object could experience a rebrightening in the next couple of days.