Project Abstract: The main objective of this project is to improve the VLBI estimation accuracy of Universal Time (UT1). For this purpose, New UT1 parameters, with an improved accuracy relatively to those produced by the IVS Intensive standard analyse, were estimated by means of assimilating the troposphere zenith delays, troposphere gradients, and polar motion components from Global Navigation Satellite Systems (GNSS) into the analysis of VLBI Intensive sessions. The New UT1 series were then be made publicly available through Hacettepe University servers as the outcomes of the project. The novelty of this project is improving the accuracy of UT1 estimate of VLBI by means of incorporating certain GNSS parameters into the analysis of VLBI Intensive sessions. In four different types of newly developed analyze methods, UT1 estimation was carried out by means of assimilating GNSS parameters into the analysis of VLBI Intensive sessions in different variations. The new analyze method of which New UT1 product fits best to GNSS length‑of‑day time series is used for continuous and automatic UT1 estimation. For the first time in Turkey, the daily time series of one of the Earth orientation parameters i.e. Universal Time (UT1) was produced routinely and made publicly available. The mean accuracy improvement of the UT1 estimates derived from the new analyze methods w.r.t. the IVS standart analyze method is found about 2 to 3 microseconds per day considering over a 10 years of data set from 2008 till 2018. The New UT1 product of the project would be used by the space agencies, institutes of geodesy and astronomy, International VLBI Service for Geodesy and Astrometry (IVS), International GNSS Service (IGS), International Earth Rotation and Reference Systems Service (IERS), and Earth and space science research and application centers. The New UT1 product is expected to provide a basis for new researches.
Publications of the project
K. Teke, M.F. Öcal, M. Nohutcu, G.O. Ahi (2017) VLBI Intensive Oturumlarının Analizi ile Evrensel Zamanın (UT1) İzlenmesi, Afyon Kocatepe Üniversitesi Fen ve Mühendislik Bilimleri Dergisi, 17 (3), 1004-1018, doi: 10.5578/fmbd.66171. >> View article
K. Teke, M.F. Öcal (2017) Yüksek-Frekanslı Yer Dönme Parametrelerinin IVS-CONT14 Kampanyasının Analizi ile Kestirimi ve IERS2010 Modeli ile Karşılaştırılması, Afyon Kocatepe Üniversitesi Fen ve Mühendislik Bilimleri Dergisi, 17 (2), 628-637, doi: 10.5578/fmbd.58667. >> View article
UT1-UTC series as the final products of the project:
Standard IVS Analysis (Analysis1: StandartUT1(A1))
Analysis with a priori gradients from GNSS (Analysis2: NewUT1(A2))
Analysis with a priori polar motion coordinates from GNSS (Analysis4: NewUT1(A4))
Project Staff
Supervisor: Kamil Teke
Scholar: Mehmet Fikret Öcal
Researchers: Metin Nohutcu ve Gonca Okay Ahi
Advisors: Mahmut Onur Karslıoğlu ve Orhan Akyılmaz
Project Duration: 3 years (15 October 2015 - 15 October 2018)