Sciences (VeUAS) has developed an 800 m single-baseline interferometer consisting of 32 m (IR) and 16 m (IB) radio telescopes with 15 arcseconds of angular resolution. Irbene radio telescopes are operating at C/M/X-band (4.5-8.8 GHz). Raw telescope data are correlated with the Software FX Correlator (SFXC) [1] and output visibilities are calibrated with a ParselTongue * pipeline. Data processing techniques provide a velocity resolution of 0.088 𝑘𝑚𝑠 −1 and spectral resolution of 0.002 MHz and enabling observations to approach the theoretical sensitivity limit of the interferometer, at about 6 mJy for a 120 s integration. We propose to use the Irbene interferometer for discoveries in a new age of transient astrophysics. In this paper, we will show correlation and calibration schema and initial monitoring results.
Modern scientific research particularly radio astronomi- cal spectroscopic observations cannot be imagined without appropriate software suite. That is necessary because of two reasons 1) data are in digital form and 2) data processing is a complex multi-step process. In this paper created in VIRAC data processing suite for a single radio telescope, space maser observations are presented. Software Defined Radio (SDR) backend data processing is described. Implementation of the frequency switching algorithm, acquisition of observation data and their format for storing are discussed. Multiple ways to display the observation results are highlighted.
The variability study of 6.7 GHz methanol masers has become a useful way to improve our understanding of the physical conditions in high-mass star-forming regions. Based on the single-dish monitoring using the Irbene telescopes, we selected three sources with close sky positions.We imaged them using the European Very Long Baseline Interferometer Network and searched available data on VLBI archives to follow detailed changes in their structures and single maser spot variability. All three targets show a few groups of maser cloudlets of a typical size of 3.5 mas and the majority of them show linear or arched structures with velocity gradients of order 0.22 km s−1 mas−1. The cloudlets and overall source morphologies are remarkably stable on time scales of 7-15 yr supporting a scenario of variability due to changes in the maser pumping rate.
We analyze calibration errors that occur during the single-dish observations at the Irbene RT-32 radio telescope when calibration is done using noise diode. Only frequency switched mode of spectral line observations is considered. The purpose of the article is to find possible values of noise diode temperature Tcal and period of switching oscillator frequency 2tq. For this, we have analyzed the formula for calculating the antenna temperature of the source. It is shown that noise diode temperature affects the standard deviation of source antenna temperature σTs and the error of source antenna temperature δTs caused by instability of system temperature. tq affects the stability of the characteristics of the receiving system. In this article, the dependencies between Tcal, tq, σTs and δTs were found and analyzed. Based on these dependencies, possible values of Tcal and tq are found.
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