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## Features of the SRT and RATAN-600 calibration

Transactions of IAA RAS, issue 47, 38–42 (2018)

Keywords: calibration measurements, SEFD, noise signal generator, space radio telescope, RATAN-600, RadioAstron, main antenna parameters, VLBI.

### Abstract

The general and specific questions on the flux density calibration of measurements and their decisions applied to the RATAN-600 radio telescope and the RadioAstron space telescope (SRT) are discussed. We analyzed the known calibration methods with using the System noise Equivalent Flux Density (SEFD=Fsys, Jy) and the Noise Signal generator (NS, Fns, Jy). In order to improve the accuracy of calibrations it is important to take into account the variability of the noise contribution from elements of the antenna-feeder tract with the losses (calibrating with SEFD) as well as to use the several independent noise generators to average their residual instability (calibrating with NS). We propose a new method of “self-calibration” for the RATAN-600 sectors which has been tested according to synchronous observations of a large number of quasi-point radio sources including strong variable objects and the secondary calibrators in the wide declination range. The first positive results of testing this method at wavelengths of 1.4, 2.7 and 6.2 cm using the North and South sectors simultaneously with a Flat reflector are presented. Observations have been done during 1-7th of December 2017. We observed ten secondary calibrators in the meridian and about 100 active galactic nuclei (like calibrators too, with fluxes greater than 1 Jy) from the RadioAstron survey sample in the declination range from minus 40 up to plus 49 degrees. Tuning the calibration was performed for the first time: 1) in the whole elevation range of the RATAN-600 from 6 up to 95 degrees, 2) for both antenna sectors, 3) independently on the variability of the source used. The RATAN-600 is a telescope with several antenna configurations. Because of the possibility to conduct observations with them synchronously, we realized the search and compensation of the systematic errors for the calibration curves in flux density measuring.

### Citation

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Yu. A. Kovalev, Yu. V. Sotnikova, A. K. Erkenov, A. V. Popkov, L. N. Volvach, V. I. Vasilkov, M. M. Lisakov, T. A. Semenova, P. G. Tsybulev. Features of the SRT and RATAN-600 calibration // Transactions of IAA RAS. — 2018. — Issue 47. — P. 38–42. @article{kovalev2018, abstract = {The general and specific questions on the flux density calibration of measurements and their decisions applied to the RATAN-600 radio telescope and the RadioAstron space telescope (SRT) are discussed. We analyzed the known calibration methods with using the System noise Equivalent Flux Density (SEFD=Fsys, Jy) and the Noise Signal generator (NS, Fns, Jy). In order to improve the accuracy of calibrations it is important to take into account the variability of the noise contribution from elements of the antenna-feeder tract with the losses (calibrating with SEFD) as well as to use the several independent noise generators to average their residual instability (calibrating with NS). We propose a new method of “self-calibration” for the RATAN-600 sectors which has been tested according to synchronous observations of a large number of quasi-point radio sources including strong variable objects and the secondary calibrators in the wide declination range. The first positive results of testing this method at wavelengths of 1.4, 2.7 and 6.2 cm using the North and South sectors simultaneously with a Flat reflector are presented. Observations have been done during 1-7th of December 2017. We observed ten secondary calibrators in the meridian and about 100 active galactic nuclei (like calibrators too, with fluxes greater than 1 Jy) from the RadioAstron survey sample in the declination range from minus 40 up to plus 49 degrees. Tuning the calibration was performed for the first time: 1) in the whole elevation range of the RATAN-600 from 6 up to 95 degrees, 2) for both antenna sectors, 3) independently on the variability of the source used. The RATAN-600 is a telescope with several antenna configurations. Because of the possibility to conduct observations with them synchronously, we realized the search and compensation of the systematic errors for the calibration curves in flux density measuring.}, author = {Yu.~A. Kovalev and Yu.~V. Sotnikova and A.~K. Erkenov and A.~V. Popkov and L.~N. Volvach and V.~I. Vasilkov and M.~M. Lisakov and T.~A. Semenova and P.~G. Tsybulev}, doi = {10.32876/ApplAstron.47.38-42}, issue = {47}, journal = {Transactions of IAA RAS}, keyword = {calibration measurements, SEFD, noise signal generator, space radio telescope, RATAN-600, RadioAstron, main antenna parameters, VLBI}, pages = {38--42}, title = {Features of the SRT and RATAN-600 calibration}, url = {http://iaaras.ru/en/library/paper/1891/}, year = {2018} } TY - JOUR TI - Features of the SRT and RATAN-600 calibration AU - Kovalev, Yu. A. AU - Sotnikova, Yu. V. AU - Erkenov, A. K. AU - Popkov, A. V. AU - Volvach, L. N. AU - Vasilkov, V. I. AU - Lisakov, M. M. AU - Semenova, T. A. AU - Tsybulev, P. G. PY - 2018 T2 - Transactions of IAA RAS IS - 47 SP - 38 AB - The general and specific questions on the flux density calibration of measurements and their decisions applied to the RATAN-600 radio telescope and the RadioAstron space telescope (SRT) are discussed. We analyzed the known calibration methods with using the System noise Equivalent Flux Density (SEFD=Fsys, Jy) and the Noise Signal generator (NS, Fns, Jy). In order to improve the accuracy of calibrations it is important to take into account the variability of the noise contribution from elements of the antenna-feeder tract with the losses (calibrating with SEFD) as well as to use the several independent noise generators to average their residual instability (calibrating with NS). We propose a new method of “self-calibration” for the RATAN-600 sectors which has been tested according to synchronous observations of a large number of quasi-point radio sources including strong variable objects and the secondary calibrators in the wide declination range. The first positive results of testing this method at wavelengths of 1.4, 2.7 and 6.2 cm using the North and South sectors simultaneously with a Flat reflector are presented. Observations have been done during 1-7th of December 2017. We observed ten secondary calibrators in the meridian and about 100 active galactic nuclei (like calibrators too, with fluxes greater than 1 Jy) from the RadioAstron survey sample in the declination range from minus 40 up to plus 49 degrees. Tuning the calibration was performed for the first time: 1) in the whole elevation range of the RATAN-600 from 6 up to 95 degrees, 2) for both antenna sectors, 3) independently on the variability of the source used. The RATAN-600 is a telescope with several antenna configurations. Because of the possibility to conduct observations with them synchronously, we realized the search and compensation of the systematic errors for the calibration curves in flux density measuring. DO - 10.32876/ApplAstron.47.38-42 UR - http://iaaras.ru/en/library/paper/1891/ ER -