SIMBAD references

An extensive search for the linear C₂N radical towards the circumstellar envelope IRC+10216 has been performed. Eight frequency bands of the rotational transitions J=7/2-5/2 up to 13/2-11/2 and 17/2-15/2 up to 23/2-21/2 of the C₂N molecule including their λ-doubling components have been probed, using the IRAM 30 m telescope at Pico Veleta, Spain. However, there is no evidence for the existence of the C₂N radical towards IRC+10216. Instead, a new upper limit N_T=3.8x10^–12cm^–2 for the column density of C₂N was estimated. Additionally, at least ten yet unidentified lines have been found.