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The wide span and high density of lines in its rovibrational spectrum render hydrogen cyanide a useful spectroscopic media for referencing absolute frequencies of lasers in optical communication and dimensional metrology. We determined, for the first time to the best of our knowledge, the molecular transitions' center frequencies of the H13C14N isotope in the range from 1526 nm to 1566 nm with 1,3e-10 fractional uncertainty. We investigated the molecular transitions with a highly coherent and widely tunable scanning laser that was precisely referenced to a Hydrogen maser through an optical frequency comb. We demonstrated an approach to stabilize the operational conditions needed to maintain the constantly low pressure of the hydrogen cyanide to carry out the saturated spectroscopy with the third-harmonic synchronous demodulation. We demonstrated approximately a fourtyfold improvement in the line centers' resolution compared to the previous result., Comment: 9 pp, 4 figures. Originally submited to Optics Letters. Version 2 - please note: the measured center frequencies of the spectroscopic features were refined compared to Version 1

The laser spectroscopy is a fundamental approach for the realisation of traceable optical frequency standards. In the $1.55\,\mu$m wavelength band, widely used in telecommunications, the acetylene is the typical and the most widespread absorption media. We present our investigation of using the hydrogen cyanide (HCN) as a cost-efficient and readily available alternative, that also provides a wider frequency span (from $1527\,$nm to $1563\,$nm). We have compared the practical aspects of using new absorption media in comparison to existing experience with the acetylene with an outlook to carry out an independent measurement of the entire spectra. The results should contribute to the future inclusion of the HCN spectroscopic data into the Mise en pratique, thus allowing for the use of HCN as a reference for the realisation of traceable laser standards., Comment: CPS 2018, Lednice, CZ, September 2018; 7 pages, 7 figures