The recently concluded collaborative European project "Robust optical clocks for international timescales" (ROCIT) tackled some of the key challenges on the roadmap towards a redefinition of the SI second. This paper gives an overview of progress made on improving the robustness and automation of optical clocks and verifying their uncertainty budgets through coordinated international comparison campaigns. It also presents work on the incorporation of optical clocks into time scales, covering both their use to steer local physical time scales and their use for evaluations of hydrogen masers contributing data for the computation of International Atomic Time (TAI). The overall objective of the project was to bring European optical clocks to the stage where they could be operated routinely as secondary frequency standards, regularly contributing to TAI.

We report on operation of a new caesium fountain primary frequency standard at the Astrogeodynamical Observatory of the Polish Space Research Centre. The device was assembled and tested at the National Physical Laboratory in Teddington and subsequently transported to Borowiec where it was fully commissioned in December 2016. We demonstrate its performance in terms of stability in short- and long-term and report preliminary measurements of the systematics effects.

The remote synchronization of a Very Long Baseline Interferometry (VLBI) station with a "virtual" atomic clock delivered via an optical fiber is described. The time and frequency signals are provided from UTC(AOS) laboratory located at a distance of 345 kilometers from the VLBI station. Evaluation of the remote synchronization carried out by Joint Institute for VLBI ERIC is presented. To our best knowledge, this is the first operational fiber-optic link synchronizing VLBI observations.

The OPTIME project creates an ultra-precise time and frequency signals dissemination system based on telecommunication networks. End users obtain access to these signals without incurring huge costs for the purchase of their own atomic clocks, and receive the service related to laboratories generating international atomic time scales, to which any precise time must be referred. This document describes the final stage of OPTIME project - which developed a self-calibrating, high precision dissemination system for time and frequency reference signals based on optical fiber links and ELSTAB devices developed at AGH University.

The OPTIME project creates an ultra-precise time and frequency signals dissemination system based on telecommunication networks. End users obtain access to these signals without incurring huge costs for the purchase of their own atomic clocks, and receive the service related to laboratories generating international atomic time scales, to which any precise time must be referred. OPTIME dissemination system is based on three main elements: reference time and frequency laboratories, local time and frequency repositories and fiber optical network with specialized transmission equipment to transfers signals between laboratories, repositories and end users. This article describes OPTIME system with particular emphasis on a new 330 km long dissemination line between Space Research Centre PAS, Astrogeodynamic Observatory (AOS) at Borowiec and National Laboratory of Atomic, Molecular and Optical Physics (KL FAMO) at Torun.

In the paper the genesis, current stage and perspectives of the OPTIME project are described. The main goal of the project is to demonstrate that the new-developed at AGH technology of fiber optic transfer of the atomic clocks reference signals is ready to be used in building the domestic Time and Frequency distribution network. In the first part we summarize the two-year continuous operation of 420 km-long link connecting the Laboratory of Time and Frequency at Central Office of Measures GUM in Warsaw and Time Service Laboratory at Astrogeodynamic Obserwatory AOS in Borowiec near Poznan. For the first time, we are reporting the two year comparison of UTC(PL) and UTC(AOS) atomic timescales with this link, and we refer it to the results of comparisons performed by GPS-based methods. We also address some practical aspects of maintaining time and frequency dissemination over fiber optical network. In the second part of the paper the concept of the general architecture of the distribution network with two Reference Time and Frequency Laboratories and local repositories is proposed. Moreover the brief project of the second branch connecting repositories in Poznan Polish Supercomputing and Networking Center and Torun Nicolaus Copernicus University with the first end-users in Torun such as National Laboratory of Atomic, Molecular and Optical Physics and Nicolaus Copernicus Astronomical Center is described. In the final part the perspective of developing the network both in the domestic range as far as extention with the international connections possibilities are presented.

The main goal of OPTIME project is to design and to create an infrastructure for a long range dissemination system for transfer of ultraprecise time scale and reference frequency signals in telecommunication networks. OPTIME dissemination system is based on three main elements: reference time and frequency laboratories, local time and frequency repositories and fiber optical network with specialized transmission equipment to transfers signals between laboratories, repositories and end-users. This article describes all elements of OPTIME system with particular emphasis on local time and frequency repositories. Moreover this article also describes experience gained during more than two years of experiments on fiber connection between Central Office of Measures (GUM) in Warsaw and the Astrogeodynamic Observatory (AOS) in Borowiec, which are reference laboratories in OPTIME system.

In this work the clock parameters determination of several timing receivers TTS-4 (AOS, PL), ASHTECH-Z-XII3T (PTB, USNO) and SEPTENTRIO POLARX4TR (ORB,) by use of the Precise Point Positioning (PPP) technique were presented. The clock parameters were determined for several time links based on the data delivered by time and frequency laboratories mentioned above. The computations cover the period from June 1 2012 to May 31, 2013 and were performed in two modes with 7-day and one-month solution for all links. All RINEX data files which include phase and code GPS data were recorded in 30-second intervals. All calculations were performed by means of Natural Resource Canada's GPS Precise Point Positioning (GPS-PPP) software based on high-quality precise satellite coordinates and satellite clock delivered by IGS as the final products. The received results were compared with the results obtained by GPS CV and TWSTFT. The used independent PPP technique is a very powerful and simple method which allows for better control of antenna positions in AOS and a verification of other time transfer techniques like GPS CV, GLONASS CV and TWSTFT. The precision of the PPP technique is only comparable to the glass fiber link PL-AOS realized at present by PL and AOS time labs. Currently PPP technique is one of the main time transfer methods used at AOS considerably improving and strengthening the quality of the Polish time scales UTC(AOS), UTC(PL), and TA(PL).

The OPTIME project creates a long range dissemination system for transfer ultraprecise time scale and the references frequency signals in telecommunication networks. The highest accuracy signal is available only on fiber optical networks, but other type of networks can be used to transfer of signals with lower accuracy to adapt it to the needs of different user groups. Article also describes experience gained during an over-a-year experiment of connection between Central Office of Measures (GUM) in Warsaw and the Astrogeodynamic Observatory (AOS) in Borowiec.

This paper concerns determination of clock readings and position of two geodetic receivers: TRIMBLE NetRS and TTS-4, connected to the same antenna of Dorne Margolin choke ring type (IGS BOR1 point) with the usage of precise point positioning (PPP) technique. The TTS-4 receiver was constructed and provided with its software by the time and frequency team from Borowiec Astrogeodynamical Observatory (AOS). Parameters of the receiver clocks and antenna coordinates were determined for the period from 1 to 30 April 2011. The collected data in RINEX format include code and phase observations from GPS constellation recorded with 30 second interval. The computed positions of the antenna based on RINEX data files from TRIMBLE NetRS and TTS-4 receivers are practically the same. The differences of estimated coordinates are from 0.6 to 1.6 mm. However, the accuracy of the clock parameters computed for TRIMBLE NetRS receiver are by one order lower than for TTS-4. It means that TRIMBLE NetRS receiver synchronized with internal quartz oscillator can not be used for timing applications. Currently the AOS laboratory works on the realization and development of the PPP method are in progress. Ultimately, the method will allow very precise comparison of atomic clocks and atomic time scales over great distances based on GNSS phase measurements. This method will increase the quality of comparisons of the atomic time scales carried out in the world, as well as, significantly strengthen the quality of the Polish Atomic Time Scale - TA (PL).

The35Cl nuclear quadrupole resonance spin echo nutation spectroscopy method was used to determine asymmetry parameters,η, of the electric field gradient tensor in cyanuric chloride, 1,3,5-trichloro-cyanuric acid and 1,3-dichloro-5,5-dimethylhydantoin. For comparison of advantages and drawbacks of some data processing methods we have tried integral transforms of nutation interferogram (pseudo-FID) data (Hankel and Hartley transforms) alternative to the Fourier transform. Another processing method, which provides a power spectrum estimated from time-domain data, is the maximum entropy method (MEM), and we applied the Burg algorithm version of it. We found that MEM gives the best enhancement of the nutation spectrum resolution and the signal-to-noise ratio, provided the number of autocorrelation coefficients is chosen for optimum performance of the Burg algorithm, otherwise estimated singularities in the nutation spectrum can be obscured by multiple spurious peaks or the spectrum resolution is low. In the Hankel transform with the first-order Bessel functions the improvement in resolution is achieved at the expense of the overall signal-to-noise ratio and for noisy experimental data this transform did not show reliable results. The Hartley transform gives a resolution better than the Fourier transform but worse than the two other methods. Unlike the Hankel transform after the Hartley transform the signal-to-noise ratio is not degraded. Theη parameter determined by MEM for cyanuric chloride was 18%, which is close to previously reported values. For 1,3,5-trichloro-cyanuric acidη = 20% and for the two chlorine sites in 1,3-dichloro-5,5-dimethylhydantoinη = 0 and 12% respectively. These values are in substantial agreement with the anticipated double bond character of N-Cl bonds in the two last compounds.

Pyridine N-oxides form two types of crystalline complexes with phentachlorophenol, with 1:1 and 1:2 base-to-acid ratios. The 1:2 complex of 2,6-dimethylpyridine N-oxide with pentachlorophenol crystallizes in space group P1̄ with a = 7.335(1) Å, b = 11.324(2) Å, c = 15.824(2) Å, α = 100.38(1)°, β = 94.63(1)°, γ = 106.60(1)°, V = 1226.7(6) Å3 and Z = 2. The structure has been refined to R = 0.046 for 3408 observed Mo Kα reflections. The oxygen atom of the N-oxide group accepts hydrogen bonds from two molecules of pentachlorophenol, with Otctdot;O distances of 2.639(5) and 2.642(5) Å and OHO angles of 141.2° and 157.6°, respectively. Both NOtctdot;HO bridges are formed in, or near, the directions of the electron lone-pairs of the N-oxygen atom. The two pentachlorophenol rings (A and B) are nearly parallel to each other and they are almost perpendicular to the pyridine ring. FTIR spectra of eleven 1:2 complexes in the solid state are similar and independent of the proton acceptor properties of the N-oxides. Five lines in the 35Cl NQR spectra of the 1:2 complexes provide evidence that both molecules of pentachlorophenol are equivalent. In CHCl3 solution, all the 1:2 complexes exist as a mixture of the 1:1 complex and pentachlorophenol.

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The presence of four resonance peaks from two nitrogen atoms in the 14N nuclear quadrupole resonance (NQR) spectrum of 1,8-bis(dimethylamino)naphthalene (DMAN) confirms the asymmetry of this molecule in the crystal. Spectroscopic parameters such as transition frequencies as well as the asymmetry parameters of the electric field gradient (EFG) tensors and differences in sigma bond occupation numbers have been assigned to particular nitrogen atoms in the molecule.

The force needed to press the key in a simple reaction time task was measured as a function of stimulus intensity for visual and auditory stimuli in three experiments using a total 45 male and female human subjects. Intensity ranged from 0.316 to 1995 cd/m2 for visual stimuli and from ranged from 47 to 102 dB for auditory stimuli. We found, in agreement with Angel's (1973) original study, that for auditory stimuli higher intensity is accompanied by a larger force. Surprisingly, in the case of visual stimuli the intensity does not influence the force. These findings are explained by the assumption that the changes of force reflect the changes of unspecific activation level evoked by immediate arousal. Thus, the different behaviour of force for these two modalities is in agreement with the common view that loud auditory stimuli are arousing while intense visual ones are not.

Low-temperature 13C and 1H MAS NMR and 14N NQR spectra of solid 1,8-bis(dimethylamino)naphthalene (DMAN) have been measured. X-Ray diffraction shows that the molecule is more symmetric than at room temperature. The low-temperature geometry of DMAN is very similar to the ab initio optimized geometry. Solid-state NMR and nuclear quadrupole resonance (NQR) confirm the symmetry of the molecule at low temperature despite the asymmetry of intermolecular interactions in the crystal. Experimental values of the principal components of electric field gradients at 14N, which characterize the properties of the lone pair electrons of the nitrogen atoms, are in good agreement with the ab initio calculated values.