Probst, Rafael A.Rafael A.ProbstMilaković, DinkoDinkoMilakovićToledo-Padrón, BorjaBorjaToledo-PadrónLo Curto, GaspareGaspareLo CurtoAvila, GerardoGerardoAvilaBRUCALASSI, ANNAANNABRUCALASSICanto Martins, Bruno L.Bruno L.Canto Martinsde Castro Leão, IzanIzande Castro LeãoEsposito, MassimilianoMassimilianoEspositoGonzález Hernández, Jonay I.Jonay I.González HernándezGrupp, FrankFrankGruppHänsch, Theodor W.Theodor W.HänschKellermann, HannaHannaKellermannKerber, FlorianFlorianKerberMandel, OlafOlafMandelManescau, AntonioAntonioManescauPozna, EszterEszterPoznaRebolo, RafaelRafaelRebolode Medeiros, José R.José R.de MedeirosSteinmetz, TiloTiloSteinmetzSuárez Mascareño, AlejandroAlejandroSuárez MascareñoUdem, ThomasThomasUdemUrrutia, JosefinaJosefinaUrrutiaWu, YuanjieYuanjieWuPasquini, LucaLucaPasquiniHolzwarth, RonaldRonaldHolzwarth2025-02-122025-02-1220202397-3366http://hdl.handle.net/20.500.12386/35917Laser frequency combs (LFCs) are well on their way to becoming the next-generation calibration sources for precision astronomical spectroscopy. This development is considered key in the hunt for low-mass rocky exoplanets around solar-type stars whose discovery with the radial-velocity method requires cm/s Doppler precision. In order to prove such precise calibration with an LFC, it must be compared to another calibrator of at least the same precision. Being the best available spectrograph calibrator, this means comparing it to a second fully independent LFC. This test had long been pending, but our installation of two LFCs at the ultra-stable spectrograph HARPS presented the so far unique opportunity for simultaneous calibrations with two separate LFCs. Although limited in time, the test results confirm the 1 cm/s stability that has long been anticipated by the astronomical community.ELETTRONICOenArticle10.1038/s41550-020-1010-x2-s2.0-85079451853https://arxiv.org/abs/2002.08868https://ui.adsabs.harvard.edu/abs/2020NatAs...4..603Phttps://www.nature.com/articles/s41550-020-1010-x2020NatAs...4..603PFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_17 Instrumentation – telescopes, detectors and techniques