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ATEL # 2503; M. Modjaz, A. V. Filippenko, J. M. Silverman, I. K. W. Kleiser, and A. J. L. Morton (UC Berkeley)
on 24 Mar 2010; 9:05 UT
Password Certification: Maryam Modjaz (firstname.lastname@example.org)
Subjects: Nova, Supernova
We report spectroscopic analysis of the host galaxy SDSS J123527.19+270402.7 of the broad-lined SN Ic 2010ay (Drake et al. 2010, CBET 2224) based on the strong H II region emission lines superimposed on the SN spectrum obtained on March 22 UT with the 3-m Shane reflector (+ Kast) at Lick Observatory (range 340-1000 nm, see ATEL #2501). After subtracting the SN contribution using the same technique as in Modjaz et al. (2008, AJ, 135, 1136), we measure the intensities of host-galaxy emission lines of the Balmer series, as well as of [O III], [O II], and [N II]. The spectrum indicates reddening with E(B-V) = 0.3 mag as deduced from the observed H-alpha/H-beta intensity ratio. Furthermore, we compute the oxygen abundance in the following scales: Kewley & Dopita (2002): 12+log(O/H) = 8.4, Pettini & Pagel (2004, O3N2) 12+log(O/H) = 8.2. In each scale, the value of SN 2010ay's hostgalaxy is at the borderline between those of broad-lined SN Ic with and without observed long-duration GRBs shown by Modjaz et al. (2008, Figure 5), and thus we encourage further observations that may constrain the presence of an off-axis GRB associated with SN 2010ay. The measured abundance value corresponds to roughly 0.3 Z_sun using the Pettini & Pagel scale and the solar oxygen abundance of 12 + log(O/H) = 8.69 (Asplund et al 2009 ARA&A, 47,481). We also note that SN 2010ay is probably even more luminous than suggested by Prieto et al. (CBET 2224), since the SN is probably reddened; hence M_V(SN) < -19.4 mag.