Ground based in situ observations of online_gc at Chilbolton Observatory (GB1055R). These measurements are gathered as a part of the following projects EMEP and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: 2-methylbutane in air (mass_fraction_of_2_methylbutane_in_air), 2-methylpropane in air (mass_fraction_of_2_methylpropane_in_air), benzene in air (mass_fraction_of_benzene_in_air), ethane in air (mass_fraction_of_ethane_in_air), ethene in air (mass_fraction_of_ethene_in_air), ethylbenzene in air (mass_fraction_of_ethylbenzene_in_air), ethyne in air (mass_fraction_of_ethyne_in_air), m-p-xylene in air (mass_fraction_of_m_p_xylene_in_air), n-butane in air (mass_fraction_of_butane_in_air), n-pentane in air (mass_fraction_of_pentane_in_air), o-xylene in air (mass_fraction_of_o_xylene_in_air), propane in air (mass_fraction_of_propane_in_air), propene in air (mass_fraction_of_propene_in_air), toluene in air (mass_fraction_of_toluene_in_air)