Common-clock very long baseline interferometry using a coherent optical fiber link

Year: 2020

Authors: Clivati C., Aiello R., Bianco G., Bortolotti C., De Natale P., Di Sarno V., Maddaloni P., Maccaferri G., Mura A., Negusini M., Levi F., Perini F., Ricci R., Roma M., Amato Santamaria L., Siciliani de Cumis M., Stagni M., Tuozzi A., Calonico D.

Autors Affiliation: Ist Nazl Ric Metrol INRIM, Str Cacce 91, I-10135 Turin, Italy; CNR, INO, Via Campi Flegrei 34, Pozzuoli, Italy; Complesso Univ MS Angelo, Sez Napoli, INFN, Via Cintia, Naples, Italy; ASI, Ctr Geodesia Spaziale G Colombo, CGS, Matera, Italy; INAF, IRA, Ist Radioastron, Via Gobetti 101, Bologna, Italy; ASI, Rome, Italy.

Abstract: Among the most powerful techniques for the exploration of the Universe is very long baseline interferometry (VLBI), which is based on the simultaneous observation of radio sources in the sky with arrays of distant ground-based antennas. One of the effects currently limiting its ultimate sensitivity is the phase-instability of the reference clocks adopted at each antenna. This termcan be made negligible delivering the same clock signal to multiple telescope sites using optical fibers. We realized such an infrastructure by disseminating a coherent optical frequency signal to two distant radio telescopes using a 1739-km-long fiber.We performed a 24 h geodetic VLBI campaign in which the same clock reference was used at both telescopes and analyzed it using standard VLBI procedures. The results were consistent with the expectations, confirming that the proposed approach is feasible and configures as a novel tool for studying the role of clocks, troposphere, and systematic effects in the ultimate VLBI resolution.

Journal/Review: OPTICA

Volume: 7 (8)      Pages from: 1031  to: 1037

More Information: Ministero dellŽIstruzione, dellŽUniversita e della Ricerca (20152MRAKH), (MetGeSp); Agenzia Spaziale Italiana (DTF-Matera); European Metrology Programme for Innovation and Research (EMPIR-17IND14-WRITE), (EMPIR-18SIB06-TIFOON).
KeyWords: FREQUENCY; GEODESY; BAND
DOI: 10.1364/OPTICA.393356

Citations: 47
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