Improving pointing of Toruń 32-m radio telescope: effects of rail surface irregularities

Lew, Bartosz

doi:10.1007/s10686-018-9573-6

Cited by 11 publications

(5 citation statements)

References 37 publications

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“…The full-beam width at half maximum of the antenna at 6.7 GHz was 5. 8, and the pointing error was ∼25 before mid-2016 and ∼10 later (Lew 2018). The system temperature ranged from 25 to 40 K. The data were dual-polarisation taken in frequency switching mode.…”

Section: Single-dish Observationsmentioning

confidence: 99%

Discovery of recurrent flares of 6.7 GHz methanol maser emission in Cepheus A HW2

Durjasz

Szymczak

Олеч

et al. 2022

A&A

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Context. Class II methanol masers at 6.7 GHz originate close to high-mass young stellar objects (HMYSOs). Their high sensitivity to local condition variations makes them a useful marker of the activity of the emerging massive stars. Aims. We aim to closely examine the variability of the 6.7 GHz CH3OH masers in Cep A HW2 using the new and archival single-dish and high-resolution Very-Long-Baseline Interferometry (VLBI) datasets. Methods. We monitored 6.7 GHz methanol masers towards the target between 2009 and 2021 using the Torun 32m radio telescope, and analysed nine datasets of VLBI observations taken over 16 yr. Results. Faint, extremely redshifted maser emission located close to the presumed central star position and coincident with the radio jet shows flaring activity with a period of ~5 yr. Flares have an asymmetric profile with a rise-to-decay time ratio of 0.18 and relative amplitude higher than 10. The velocity of the flaring cloudlets drifts at a rate of 3–4 × 10−5 km s−1 d−1 for about 11.5 yr of the monitoring. The time-lag between the peaks of the two flaring features implies a propagation speed of the exciting factor of ~1000 km s−1. Synchronised and anticorrelated variations of the flux density of blue- and redshifted features begin ~2.5 yr after flares of the extremely redshifted emission. Conclusions. Our observations suggest that the recurrent flares are the response of low-gain unsaturated maser regions to a relatively low increase in luminosity, which has little effect on the behaviour of most maser regions of higher gain.

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Section: Single-dish Observationsmentioning

confidence: 99%

Discovery of recurrent flares of 6.7 GHz methanol maser emission in Cepheus A HW2

Durjasz

Szymczak

Олеч

et al. 2022

A&A

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show abstract

“…The new observations were carried out from February 2013 to October 2018. The beam full width at half maximum of the antenna at 6.7 GHz was 5.8 arcmin and rms pointing error was ∼25 arcsec but it was reduced to 10 arcsec from mid-2016 (Lew 2018). The system temperature was between 25 and 40 K. The data were dual polarization taken in frequency switching mode using a 1 MHz shift.…”

Section: Observationsmentioning

confidence: 99%

A highly variable methanol maser in G111.256–0.770

Durjasz

Szymczak

Олеч

2019

Monthly Notices of the Royal Astronomical Society

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G111.256−0.770 is a high-mass young stellar object associated with a weak 6.7 GHz methanol maser showing strong variability. We present results of a multi-epoch monitoring program of the target, conducted with the Torun 32 m telescope for more than a decade. We found that the isotropic maser luminosity varied by a factor 16 on a timescale of 5−6 yr and individual features showed small amplitude short-lived (∼0.2 yr) bursts superimposed on higher amplitude slow (>5 yr) variations. The maser integrated flux density appears to be correlated with the near-infrared flux observed with the (NEO)WISE, supporting radiative pumping of the maser line.

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“…The research has made use of the SIMBAD data base, operated at CDS (Strasbourg, France), as well as NASA's Astrophysics Data System Bibliographic Services. This research made use of Astropy 4 , a community-developed core Python package for Astronomy (Astropy Collaboration et al 2013, 2018…”

Section: Acknowledgementsmentioning

confidence: 99%

Discovery of recurrent flares of 6.7 GHz methanol maser emission in Cepheus A HW2

Durjasz,

Szymczak,

Olech

et al. 2022

Preprint

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Context. Class II methanol masers at 6.7 GHz originate close to high-mass young stellar objects (HMYSOs). Their high sensitivity to local condition variations makes them a useful marker of the activity of the emerging massive stars. Aims. We aim to closely examine the variability of the 6.7 GHz CH 3 OH masers in Cep A HW2 using the new and archival single-dish and high-resolution Very-Long-Baseline Interferometry (VLBI) datasets. Methods. We monitored 6.7 GHz methanol masers towards the target between 2009 and 2021 using the Torun 32 m radio telescope, and analysed nine datasets of VLBI observations taken over 16 yr. Results. Faint, extremely redshifted maser emission located close to the presumed central star position and coincident with the radio jet shows flaring activity with a period of ∼ 5 yr. Flares have an asymmetric profile with a rise-to-decay time ratio of 0.18 and relative amplitude higher than 10. The velocity of the flaring cloudlets drifts at a rate of 3-4 × 10 −5 km s −1 d −1 for about 11.5 yr of the monitoring. The time-lag between the peaks of the two flaring features implies a propagation speed of the exciting factor of ∼ 1000 km s −1 . Synchronised and anticorrelated variations of the flux density of blue-and redshifted features begin ∼ 2.5 yr after flares of the extremely redshifted emission. Conclusions. Our observations suggest that the recurrent flares are the response of low-gain unsaturated maser regions to a relatively low increase in luminosity, which has little effect on the behaviour of most maser regions of higher gain.

show abstract

Improving pointing of Toruń 32-m radio telescope: effects of rail surface irregularities

Cited by 11 publications

References 37 publications

Discovery of recurrent flares of 6.7 GHz methanol maser emission in Cepheus A HW2

Discovery of recurrent flares of 6.7 GHz methanol maser emission in Cepheus A HW2

A highly variable methanol maser in G111.256–0.770

Discovery of recurrent flares of 6.7 GHz methanol maser emission in Cepheus A HW2

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