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Results of Monitoring OH Maser Emission at Frequency 1665 MHz in Sources W3, W49, W51 and W75 using RT-32 Radio Telescope at Svetloe Observatory

A. V. Ipatov, I. A. Rahimov, S. A. Grenkov, N. E. Kol’tsov

Transactions of IAA RAS, issue 60, 27–38 (2022)

Keywords: cosmic maser, hydroxyl radio emission, maser variability, spectrometer, spectral analysis of radio emission, calibration of spectrums

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Abstract

The main goal of this article is to reveal the long-term variability of the spectra of cosmic maser radio emission from interstellar hydroxyl over the period 2009–2020 in sources W3(OH), W49, W51 and W75 at the frequency of 1665.402 MHz in two circular polarizations. These sources have been observed within the Ru-OH observing program at the RT-32 radio telescope in the “Svetloe” observatory since 2006. It is supposed that long-term variations in cosmic maser emission may be caused by variations in the internal properties of the sources. For this reason generalized data on the variability of individual components of maser sources may be an area of interest to astrophysicists when constructing mathematical models of space masers and analyzing the physical conditions in star-forming regions. Оbservations and processing technique. Observations of hydroxyl masers are carried out using a standard receiver of the L band radio telescope RT-32, spectrometer and down converters. Registration of the emission source spectra is carried out according to the “On source – Off source” method with calibration of the flux amplitude by a stable calibration source of radio emission in the continuum. Spectral profiles are being recorded over a specified time interval (about 180–600 s). Afterwards they are thoroughly culled depending on distortion by interference and/or instrumental effects and then statistically processed. As a result of the statistical processing the dependences of radio emission intensity are derived, which enable to reveal trends towards amplification or attenuation of components of the spectral profiles and in some cases to reveal long-term amplification or attenuation of these components during flare activity of maser sources. Main results. Regular spectral observations of the regions of OH maser sources in W3(OH), W49, W51 and W75 at a frequency of 1665 MHz carried out by the RT-32 radio telescope at the “Svetloe” observatory made it possible to trace and reveal the variability of discrete components of their emission based on homogeneous data.

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A. V. Ipatov, I. A. Rahimov, S. A. Grenkov, N. E. Kol’tsov. Results of Monitoring OH Maser Emission at Frequency 1665 MHz in Sources W3, W49, W51 and W75 using RT-32 Radio Telescope at Svetloe Observatory // Transactions of IAA RAS. — 2022. — Issue 60. — P. 27–38.

@article{ipatov2022,
  abstract = {The main goal of this article is to reveal the long-term variability of the spectra of cosmic maser radio emission from interstellar hydroxyl over the period 2009–2020 in sources W3(OH), W49, W51 and W75 at the frequency of 1665.402 MHz in two circular polarizations. These sources have been observed within the Ru-OH observing program at the RT-32 radio telescope in the “Svetloe” observatory since 2006. It is supposed that long-term variations in cosmic maser emission may be caused by variations in the internal properties of the sources. For this reason generalized data on the variability of individual components of maser sources may be an area of interest to astrophysicists when constructing mathematical models of space masers and analyzing the physical conditions in star-forming regions. 
Оbservations and processing technique. Observations of hydroxyl masers are carried out using a standard receiver of the L band radio telescope RT-32, spectrometer and down converters. Registration of the emission source spectra is carried out according to the “On source – Off source” method with calibration of the flux amplitude by a stable calibration source of radio emission in the continuum. Spectral profiles are being recorded over a specified time interval (about 
180–600 s). Afterwards they are thoroughly culled depending on distortion by interference and/or instrumental effects and then statistically processed.
As a result of the statistical processing the dependences of radio emission intensity are derived, which enable to reveal trends towards amplification or attenuation of components of the spectral profiles and in some cases to reveal long-term amplification or attenuation of these components during flare activity of maser sources.
Main results. Regular spectral observations of the regions of OH maser sources in W3(OH), W49, W51 and W75 at a frequency of 1665 MHz carried out by the RT-32 radio telescope at the “Svetloe” observatory made it possible to trace and reveal the variability of discrete components of their emission based on homogeneous data.},
  author = {A.~V. Ipatov and I.~A. Rahimov and S.~A. Grenkov and N.~E. Kol’tsov},
  doi = {10.32876/ApplAstron.60.27-38},
  issue = {60},
  journal = {Transactions of IAA RAS},
  keyword = {cosmic maser, hydroxyl radio emission, maser variability, spectrometer, spectral analysis of radio emission, calibration of spectrums},
  pages = {27--38},
  title = {Results of Monitoring OH Maser Emission at Frequency 1665 MHz in Sources W3, W49, W51 and W75 using RT-32 Radio Telescope at Svetloe Observatory},
  url = {http://iaaras.ru/en/library/paper/2117/},
  year = {2022}
}

TY  - JOUR
TI  - Results of Monitoring OH Maser Emission at Frequency 1665 MHz in Sources W3, W49, W51 and W75 using RT-32 Radio Telescope at Svetloe Observatory
AU  - Ipatov, A. V.
AU  - Rahimov, I. A.
AU  - Grenkov, S. A.
AU  - Kol’tsov, N. E.
PY  - 2022
T2  - Transactions of IAA RAS
IS  - 60
SP  - 27
AB  - The main goal of this article is to reveal the long-term variability
of the spectra of cosmic maser radio emission from interstellar
hydroxyl over the period 2009–2020 in sources W3(OH), W49, W51 and
W75 at the frequency of 1665.402 MHz in two circular polarizations.
These sources have been observed within the Ru-OH observing program
at the RT-32 radio telescope in the “Svetloe” observatory since 2006.
It is supposed that long-term variations in cosmic maser emission may
be caused by variations in the internal properties of the sources.
For this reason generalized data on the variability of individual
components of maser sources may be an area of interest to
astrophysicists when constructing mathematical models of space masers
and analyzing the physical conditions in star-forming regions.
Оbservations and processing technique. Observations of hydroxyl
masers are carried out using a standard receiver of the L band radio
telescope RT-32, spectrometer and down converters. Registration of
the emission source spectra is carried out according to the “On
source – Off source” method with calibration of the flux amplitude by
a stable calibration source of radio emission in the continuum.
Spectral profiles are being recorded over a specified time interval
(about   180–600 s). Afterwards they are thoroughly culled depending
on distortion by interference and/or instrumental effects and then
statistically processed.  As a result of the statistical processing
the dependences of radio emission intensity are derived, which enable
to reveal trends towards amplification or attenuation of components
of the spectral profiles and in some cases to reveal long-term
amplification or attenuation of these components during flare
activity of maser sources.  Main results. Regular spectral
observations of the regions of OH maser sources in W3(OH), W49, W51
and W75 at a frequency of 1665 MHz carried out by the RT-32 radio
telescope at the “Svetloe” observatory made it possible to trace and
reveal the variability of discrete components of their emission based
on homogeneous data.
DO  - 10.32876/ApplAstron.60.27-38
UR  - http://iaaras.ru/en/library/paper/2117/
ER  -