Impact of Mg <scp>ii</scp> interstellar medium absorption on near-ultraviolet exoplanet transit measurements

Ultraviolet (UV) transmission spectroscopy probes atmospheric escape, which has a significant impact on planetary evolution. If unaccounted for, interstellar medium absorption (ISM) at the position of specific UV lines might bias transit depth measurements, and thus potentially affect (non-)detection features in spectra. Ultimately, this is connected to so called ``resolution-linked bias'' (RLB) effect. We present parametric study quantifying unresolved or unconsidered ISM measurements MgII h&k resonance (i.e. 2802.705 {\AA} 2795.528 respectively) near-ultraviolet spectral range. consider main-sequence stars different types vary shape amount chromospheric emission, absorption, as well their relative velocities. also evaluate role played by integration bin resolution. an open-source tool enabling one quantify measurements. further apply few already soon be observed systems. On average, we find that ignoring leads biases comparable uncertainties obtained from observations published date. However, considering induced become necessary when analysing with next generation space telescopes coverage (e.g. LUVOIR, HABEX), will provide spectra significantly smaller compared what current facilities HST).