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تسجيل مستخدم جديدH$alpha$ Luminosity of ATLAS18qtd Does Not Plateau in the Nebular Phase
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We present new spectroscopic and photometric observations of ATLAS18qtd/SN 2018cqj, a fast-declining Type Ia supernova with variable H$alpha$ emission in previously-published nebular phase spectra. ATLAS18qtd is undetected in both spectroscopic and photometric observations which occurred at $sim 540~rm d$ after maximum light and $sim 230~rm d$ after the last H$alpha$ detection. With these new non-detections, we place an upper limit on the H$alpha$ luminosity of $lesssim 1.1times 10^{36}~rm{erg}~rm s^{-1}$ indicating the H$alpha$ flux decreased by a factor of $gtrsim 4$ since the previous detection. This upper limit excludes H$alpha$ emission that plateaus or increases since the previous detection but cannot confirm that the H$alpha$ emission decay rate is equivalent to the supernova decay rate.
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We present optical photometry and spectroscopy of the Type Ia supernova SN2018cqj/ATLAS18qtd. The supernova exploded in an isolated region at $sim 65$~kpc from the S0 galaxy IC~550 at $z=0.0165$ ($Dapprox 74$~Mpc) and has a redshift consistent with a
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