The RadioAstron Green Bank Earth Station

Ford, H. A.; Anderson, Ron; Belousov, K. G.; Brandt, Joe; Ford, John; Kanevsky, B. Z.; Kovalenko, A. V.; Kovalev, Y. Y.; Maddalena, R. J.; Sergeev, Sergĕı; Smirnov, Alexander; Watts, Galen; Weadon, Timothy L.

doi:10.1117/12.2056761

Cited by 12 publications

(9 citation statements)

References 8 publications

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“…The data are recorded at a rate of 128 Megabits per second, providing a total bandwidth of up to 32 MHz per circular polarization channel (Andreyanov et al 2014). The satellite telemetry and science data are received and recorded at tracking stations in Puschino (Andreyanov et al 2014) and Green Bank (Ford et al 2014) and later transferred for correlation at one of the RadioAstron correlation facilities. Accurate reconstruction of the orbit and of the momentary state vector of the Spektr-R spacecraft is achieved by combining together radiometric range and radial velocity measurements made at the satellite control stations in Bear Lakes and Ussurijsk (Russia), Doppler measurements obtained at each of the tracking stations, and laser ranging and optical astrometric measurements of the spacecraft position in the sky Zakhvatkin et al 2014).…”

Section: Imaging With Radioastronmentioning

confidence: 99%

RadioAstron space VLBI imaging of polarized radio emission in the high-redshift quasar 0642+449 at 1.6 GHz

Lobanov

Gómez

Bruni

et al. 2015

A&A

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Context. Polarization of radio emission in extragalactic jets at a sub-milliarcsecond angular resolution holds important clues for understanding the structure of the magnetic field in the inner regions of the jets and in close vicinity of the supermassive black holes in the centers of active galaxies. Aims. Space VLBI observations provide a unique tool for polarimetric imaging at a sub-milliarcsecond angular resolution and studying the properties of magnetic field in active galactic nuclei on scales of less than 10 4 gravitational radii. Methods. A space VLBI observation of high-redshift quasar TXS 0642+449 (OH 471), made at a wavelength of 18 cm (frequency of 1.6 GHz) as part of the early science programme (ESP) of the RadioAstron mission, is used here to test the polarimetric performance of the orbiting Space Radio Telescope (SRT) employed by the mission, to establish a methodology for making full Stokes polarimetry with space VLBI at 1.6 GHz, and to study the polarized emission in the target object on sub-milliarcsecond scales. Results. Polarization leakage of the SRT at 18 cm is found to be within 9% in amplitude, demonstrating the feasibility of high fidelity polarization imaging with RadioAstron at this wavelength. A polarimetric image of 0642+449 with a resolution of 0.8 mas (signifying an ∼4 times improvement over ground VLBI observations at the same wavelength) is obtained. The image shows a compact corejet structure with low (≈2%) polarization and predominantly transverse magnetic field in the nuclear region. The VLBI data also uncover a complex structure of the nuclear region, with two prominent features possibly corresponding to the jet base and a strong recollimation shock. The maximum brightness temperature at the jet base can be as high as 4 × 10 13 K.

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Section: Imaging With Radioastronmentioning

confidence: 99%

RadioAstron space VLBI imaging of polarized radio emission in the high-redshift quasar 0642+449 at 1.6 GHz

Lobanov

Gómez

Bruni

et al. 2015

A&A

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“…For (Kardashev et al 2013;Ford et al 2014) in Puschino (21:30 -06:10 UT) and Green Bank (07:30 -13:00 UT), including some extended gaps required for cooling of the motor drive of the on board highgain antenna of the Spektr-R satellite. These gaps were used for the ground-only observations of BLLac at 15 and 43 GHz (see Section 2.2), as well as observations of several calibrator sources.…”

Section: Introductionmentioning

confidence: 99%

PROBING THE INNERMOST REGIONS OF AGN JETS AND THEIR MAGNETIC FIELDS WITH RADIOASTRON. I. IMAGING BL LACERTAE AT 21 μas RESOLUTION

Gómez

Lobanov

Bruni

et al. 2016

ApJ

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145

165

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We present the first polarimetric space very long baseline interferometry (VLBI) imaging observations at 22 GHz. BLLacertae was observed in 2013 November 10 with the RadioAstron space VLBI mission, including a ground array of 15 radio telescopes. The instrumental polarization of the space radio telescope is found to be less than 9%, demonstrating the polarimetric imaging capabilities of RadioAstron at 22 GHz. Ground-space fringes were obtained up to a projected baseline distance of 7.9Earth diameters in length, allowing us to image the jet in BLLacertae with a maximum angular resolution of 21 μas, the highest achieved to date. We find evidence for emission upstream of the radio core, which may correspond to a recollimation shock at about 40 μas from the jet apex, in a pattern that includes other recollimation shocks at approximately 100 and 250 μas from the jet apex. Polarized emission is detected in two components within the innermost 0.5 mas from the core, as well as in some knots 3 mas downstream. Faraday rotation analysis, obtained from combining RadioAstron 22 GHz and groundbased 15 and 43 GHz images, shows a gradient in rotation measure and Faraday-corrected polarization vector as a function of position angle with respect to the core, suggesting that the jet in BLLacertae is threaded by a helical magnetic field. The intrinsic de-boosted brightness temperature in the unresolved core exceeds 3 10 12 K, suggesting, at the very least, departure from equipartition of energy between the magnetic field and radiating particles.

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“…In 2011 the antenna underwent refurbishment and is currently an earth station for a space-based, radio astronomy satellite, Spektr-R, part of the RadioAstron program 5 . The system has the capability of both 1-way and 2-way links with the Spektr-R spacecraft.…”

Section: The 140 Foot Telescopementioning

confidence: 99%

Space situational awareness applications for radio astronomy assets

Watts

Ford

2015

SPIE Proceedings

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The National Radio Astronomy Observatory (NRAO) builds, operates, and maintains a suite of premier radio antennas, including the 100m aperture Green Bank Telescope, the largest fully-steerable antenna in the world. For more than five decades the NRAO has focused on astrophysics, providing researchers with the most advanced instruments possible: large apertures, extremely low-noise receivers, and signal processors with high frequency and time resolution. These instruments are adaptable to Space Situational Awareness (SSA) tasks such as radar detection of objects in near-Earth and cis-Lunar space, high accuracy orbit determination, object surveillance with passive methods, and uplink and downlink communications. We present the capabilities of antennas and infrastructure at the NRAO Green Bank Observatory in the context of SSA tasks, and discuss what additions and modifications would be necessary to achieve SSA goals while preserving existing radio astronomy performance. We also discuss how the Green Bank Observatory's surrounding topography and location within the National Radio Quiet Zone will enhance SSA endeavors.

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The RadioAstron Green Bank Earth Station

Cited by 12 publications

References 8 publications

RadioAstron space VLBI imaging of polarized radio emission in the high-redshift quasar 0642+449 at 1.6 GHz

RadioAstron space VLBI imaging of polarized radio emission in the high-redshift quasar 0642+449 at 1.6 GHz

PROBING THE INNERMOST REGIONS OF AGN JETS AND THEIR MAGNETIC FIELDS WITH RADIOASTRON. I. IMAGING BL LACERTAE AT 21 μas RESOLUTION

Space situational awareness applications for radio astronomy assets

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