Over the last few years a number of software and hardware improvements have been implemented to the 32-m Cassegrain radio telescope located near Toruń. The 19-bit angle encoders have been upgraded to ...29-bit in azimuth and elevation axes. The control system has been substantially improved, in order to account for a number of previously-neglected, astrometric effects that are relevant for milli-degree pointing. In the summer 2015, as a result of maintenance works, the orientation of the secondary mirror has been slightly altered, which resulted in worsening of the pointing precision, much below the nominal telescope capabilities. In preparation for observations at the highest available frequency of 30-GHz, we use One Centimeter Receiver Array (OCRA), to take the most accurate pointing data ever collected with the telescope, and we analyze it in order to improve the pointing precision. We introduce a new generalized pointing model that, for the first time, accounts for the rail irregularities, and we show that the telescope can have root mean square pointing accuracy at the level < 8
″
and < 12
″
in azimuth and elevation respectively. Finally, we discuss the implemented pointing improvements in the light of effects that may influence their long-term stability.
We utilize ground-based, balloon-borne and satellite climatology data to reconstruct site and season-dependent vertical profiles of precipitable water vapour (PWV). We use these profiles to solve ...radiative transfer through the atmosphere, and derive atmospheric brightness temperature (Tatm) and optical depth (t) at centimetre wavelengths. We validate the reconstruction by comparing the model column PWV with photometric measurements of PWV, performed in clear sky conditions pointed towards the Sun. Based on the measurements, we devise a selection criteria to filter the climatology data to match the PWV levels to the expectations of the clear sky conditions. We apply the reconstruction to the location of a Polish 32-metre radio telescope, and characterize Tatm and t year round, at selected frequencies. We also derive the zenith distance dependence for these parameters, and discuss the shortcomings of using planar, single-layer and optically thin atmospheric models in continuum radio-source flux-density measurement calibrations. We obtain PWV-Tatm and PWV-t scaling relations in clear sky conditions, and constrain limits to which the actual Tatm and t can deviate from those derived solely from the climatological data. Finally, we suggest a statistical method to detect clear sky that involves ground-level measurements of relative humidity. Accuracy is tested using local climatological data. The method may be useful to constrain cloud cover in cases when no other (and more robust) climatological data are available.
Exp Astron (2018) pp 1-25 Over the last few years a number of software and hardware improvements have
been implemented to the 32-m Cassegrain radio telescope located near Toru\'n.
The 19-bit angle ...encoders have been upgraded to 29-bit in azimuth and elevation
axes. The control system has been substantially improved, in order to account
for a number of previously-neglected, astrometric effects that are relevant for
milli-degree pointing. In the summer 2015, as a result of maintenance works,
the orientation of the secondary mirror has been slightly altered, which
resulted in worsening of the pointing precision, much below the nominal
telescope capabilities.
In preparation for observations at the highest available frequency of 30-GHz,
we use One Centimeter Receiver Array (OCRA), to take the most accurate pointing
data ever collected with the telescope, and we analyze it in order to improve
the pointing precision.
We introduce a new generalized pointing model that, for the first time,
accounts for the rail irregularities, and we show that the telescope can have
root mean square pointing accuracy at the level ${<}8"$ and ${<}12"$ in azimuth
and elevation respectively. Finally, we discuss the implemented pointing
improvements in the light of effects that may influence their long-term
stability.
We present 30-GHz Sunyaev-Zel'dovich (SZ) observations of a statistically complete sample of galaxy clusters with the One Centimetre Receiver Array-prototype (OCRA-p). The clusters are the 18 most ...X-ray luminous clusters at z > 0.2 in the ROSAT Brightest Cluster Sample. We correct for contaminant radio sources via supplementary observations with the Green Bank Telescope, also at 30 GHz, and remove a cluster that is contaminated by an unresolved X-ray source. All 17 remaining clusters have central SZ effects with Comptonization parameter y
0 exceeding 1.9 × 10−4, and 13 are detected at significance ≥3σ. We use our data to examine scalings between y
0 and X-ray temperature, X-ray luminosity and the X-ray mass proxy Y
X, and find good agreement with predictions from self-similar models of cluster formation, with an intrinsic scatter in y
0 of about 25 per cent. We also comment on the success of the observations in the face of the contaminant source population, and the implications for upcoming cm-wave surveys.
We constrain radio source clustering towards \(Planck\)-selected galaxy clusters using the NVSS point source catalogue. The constraint can be utilised for generating realistic Sunyaev-Zeldovich ...effect (SZE) mocks, and for predicting detectable clusters count and quantifying source confusion in radio surveys.
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