Flux density and linear polarization measurements of variable radio sources at   9.00 mm (33.5 GHz)

Flett, A. M.; Henderson, C.

doi:10.1093/mnras/204.4.1285

Cited by 7 publications

(3 citation statements)

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“…4. In addition to the UMRAO and MRO data, these contain 33.5 GHz data of Flett & Henderson (1981, 1983) and 36.8 and 22 GHz data of Salonen et al (1987). We determined the long‐term trends via a linear interpolation across the local/global minima in 1981, 1986, 1994 and 2004.…”

Section: 2223−052 (3c 446)mentioning

confidence: 99%

Frequency-dependent time delays for strong outbursts in selected blazars from the Metsähovi and UMRAO monitoring data bases – II

Pyatunina

Kudryavtseva

Gabuzda

et al. 2007

Monthly Notices of the Royal Astronomical Society

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We analyse the radio light curves of the blazars 1308+326, 2223-052 and 2251+158 using University of Michigan Radio Observatory and Metsähovi Radio Observatory multifrequency monitoring data combined with high-resolution very long baseline interferometry (VLBI) observations in order to extract the properties of prominent outbursts. The outbursts are classified as 'core' and 'jet' events according to their behaviour at different frequencies and their associations with features appearing in the VLBI jet. We define the activity cycle for each blazar as the time interval between successive 'core' outbursts. The durations of the activity cycle derived in this way are >= 14 yr for 1308+326, similar to 12 yr for 2223-052 and 12.4 +/- 0.6 yr for 2251+158. We find an unusual frequency dependence for the time profiles for a major flare in 1308+326, which may provide evidence for acceleration or bending of the jet flow in the optically thick part of the emission region. Analysis of these activity cycles, combined with our earlier results, leads us to suggest that more luminous blazars possess shorter activity cycles, consistent with the accretion rates being higher in more powerful sources (relative to the Eddington rate)

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Section: 2223−052 (3c 446)mentioning

confidence: 99%

Frequency-dependent time delays for strong outbursts in selected blazars from the Metsähovi and UMRAO monitoring data bases – II

Pyatunina

Kudryavtseva

Gabuzda

et al. 2007

Monthly Notices of the Royal Astronomical Society

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“…For example, blazars produce relatively rapid and large amplitude variability in all wavebands. Long term observations of such objects show that increases in flux by a factor of up to a few over a time scale of years can be anticipated (Flett & Henderson 1983;Ennis et al 1982;Stevens et al 1994;Bower et al 1997). Observations of Zw 2 by Falcke et al (1999), provide an extreme example: a greater than 20-fold increase in brightness, from ∼0.1 Jy to ∼2 Jy, over a period of less than two years.…”

Section: Source Variabilitymentioning

confidence: 99%

First‐Year Wilkinson Microwave Anisotropy Probe ( WMAP ) Observations: Data Processing Methods and Systematic Error Limits

Hinshaw

Barnes

Bennett

et al. 2003

ASTROPHYS J SUPPL S

147

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We describe the calibration and data processing methods used to generate full-sky maps of the cosmic microwave background (CMB) from the first year of Wilkinson Microwave Anisotropy Probe (WMAP) observations. Detailed limits on residual systematic errors are assigned based largely on analyses of the flight data supplemented, where necessary, with results from ground tests. The data are calibrated in flight using the dipole modulation of the CMB due to the observatory's motion around the Sun. This constitutes a full-beam calibration source. An iterative algorithm simultaneously fits the time-ordered data to obtain calibration parameters and pixelized sky map temperatures. The noise properties are determined by analyzing the time-ordered data with this sky signal estimate subtracted. Based on this, we apply a pre-whitening filter to the time-ordered data to remove a low level of 1/f noise. We infer and correct for a small (∼1%) transmission imbalance between the two sky inputs to each differential radiometer, and we subtract a small sidelobe correction from the 23 GHz (K band) map prior to further analysis. No other systematic error corrections are applied to the data. Calibration and baseline artifacts, including the response to environmental perturbations, are negligible. Systematic uncertainties are comparable to statistical uncertainties in the characterization of the beam response. Both are accounted for in the covariance matrix of the window function and are propagated to uncertainties in the final power spectrum. We characterize the combined upper limits to residual systematic uncertainties through the pixel covariance matrix.

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“…The Crab nebula represents the most suitable candidate as absolute calibrator for the polarization angle and the linear polarization degree, given that it is the most intense polarized source in the microwave sky at angular scales of few arcminutes (Flett & Henderson 1979, 1981, 1983.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the Crab nebula polarization at 90 GHz as a calibrator for CMB experiments

Aumont

Conversi

Thum

et al. 2010

A&A

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Context. CMB experiments aiming at a precise measurement of the CMB polarization, such as the Planck satellite, need a strong polarized absolute calibrator on the sky to accurately set the detectors polarization angle and the cross-polarization leakage. As the most intense polarized source in the microwave sky at angular scales of few arcminutes, the Crab nebula will be used for this purpose. Aims. Our goal was to measure the Crab nebula polarization characteristics at 90 GHz with unprecedented precision. Methods. The observations were carried out with the IRAM 30 m telescope employing the correlation polarimeter XPOL and using two orthogonally polarized receivers. Results. We processed the Stokes I, Q, and U maps from our observations in order to compute the polarization angle and linear polarization fraction. The first is almost constant in the region of maximum emission in polarization with a mean value of α Sky = 152.1 ± 0.3 • in equatorial coordinates, and the second is found to reach a maximum of Π = 30% for the most polarized pixels. We find that a CMB experiment having a 5 arcmin circular beam will see a mean polarization angle of α Sky = 149.9 ± 0.2 • and a mean polarization fraction of Π = 8.8 ± 0.2%.

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Flux density and linear polarization measurements of variable radio sources at 9.00 mm (33.5 GHz)

Cited by 7 publications

References 0 publications

Frequency-dependent time delays for strong outbursts in selected blazars from the Metsähovi and UMRAO monitoring data bases – II

Frequency-dependent time delays for strong outbursts in selected blazars from the Metsähovi and UMRAO monitoring data bases – II

First‐Year Wilkinson Microwave Anisotropy Probe ( WMAP ) Observations: Data Processing Methods and Systematic Error Limits

Measurement of the Crab nebula polarization at 90 GHz as a calibrator for CMB experiments

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