LT Optical Spectroscopy of AT2018cow/ATLAS18qqn

ATel #11732; Daniel Perley (Liverpool JMU)
on 19 Jun 2018; 00:23 UT
Credential Certification: Daniel Perley (d.a.perley@ljmu.ac.uk)

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We obtained spectroscopy of the bright transient AT2018cow (ATLAS18qqn; Smartt et al. ATel #11727) using SPRAT (Piascik et al. 2014) on the 2-m Liverpool Telescope. The spectrum, taken at 2018-06-18.951 UT, is very blue and hot, approximately described by a power-law in flux with F_lambda ~ lambda^(-3.2). There are no strong emission or absorption features visible across the observed wavelength range (between 402-800 nm, wavelength resolution ~2 nm). In particular, we observe no features either at z=0 or at z=0.0141 (the redshift of the coincident galaxy CGCG 137-068), with the exception of weak H-alpha at the galaxy redshift which could originate from the galaxy background.