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ATEL # 2660; J. L. Prieto (Carnegie Observatories), H. E. Bond (STScI), C. S. Kochanek, R. Khan, K. Z. Stanek, T. A. Thompson (Ohio State University)
on 4 Jun 2010; 19:04 UT
Password Certification: Jose L. Prieto (firstname.lastname@example.org)
Subjects: Infra-Red, Optical, Nova, Supernova, Transients
New optical and near-IR (BVRI + JHK) images of the transient SN 2010da in NGC 300 (CBET #2289, ATEL #2632, #2633, #2636, #2637, #2638, #2639, #2640, #2648, #2658) were obtained on 2010 June 3.4 (UT) by A. Miranda with the SMARTS 1.3m telescope at Cerro Tololo and the ANDICAM camera, as part of our follow-up campaign. The magnitudes of the transient in the optical are: B=17.40, V=16.97, R=16.40, I=16.24 (+/- 0.05 mag). These measurements show that the transient has faded by 0.5-0.7 mag in 9 days with respect to the magnitudes reported by H. E. Bond (ATEL #2640). This early fading is fast compared to the light curve of the 2008 transient in NGC 300 (Bond et al. 2009, ApJ, 695, 154).
We also detect SN 2010da in the near-IR in measurements made simultaneously with the optical observations. The near-IR magnitudes of the transient, measured with respect to a bright 2MASS star in the field, are: J=15.52, H=15.00, K=14.42 (+/- 0.10 mag). These measurements indicate a strong near-IR excess with respect to a simple black-body fit to the optical fluxes (L=5.5x10^5 Lsun, T=6300 K, R=3 AU), see Fig. 1. This suggests that some of the circumstellar dust around the enshrouded mid-IR progenitor (see ATEL #2632, #2638, #2648) was not destroyed by the initial optical/UV flash. These characteristics make it similar to the 2008 optical transient in NGC 300 (Bond et al. 2009; Prieto et al. 2009, ApJ, 705, 1425). The mid-IR fluxes of the progenitor (from ATEL #2632, #2638) can be well-fitted by a modified black-body (emissivity ~1/lambda) with L=1.3x10^4 Lsun, T=890 K, and R=22 AU (see fit in Fig. 1).