J/A+A/559/A75 43GHz observation of the blazar Mrk 421 (Blasi+, 2013)
The TeV blazar Markarian 421 at the highest spatial resolution.
Blasi M.G., Lico R., Giroletti M., Orienti M., Giovannini G., Cotton W.,
Edwards P.G., Fuhrmann L., Krichbaum T.P., Kovalev Y.Y., Jorstad S.,
Marscher A., Kino M., Paneque D., Perez-Torres M.A., Piner B.G.,
Sokolovsky K.V.
<Astron. Astrophys. 559, A75 (2013)>
=2013A&A...559A..75B 2013A&A...559A..75B
ADC_Keywords: BL Lac objects ; Active gal. nuclei ; Radio sources
Keywords: galaxies: active - BL Lacertae objects: individual: Markarian 421 -
galaxies: jets
Abstract:
We report the results obtained for the AGN Markarian 421 by
model-fitting the data in the visibility plane, studing the proper
motion of jet components, the light curve, and the spectral index of
the jet features. We compare the radio data with optical light curves
obtained at the Steward Observatory, considering also the optical
polarization information.
Mrk 421 has a bright nucleus and a one-sided jet extending towards the
north-west for a few parsecs. The model-fits show that brightness
distribution is well described using 6-7 circular Gaussian components,
four of which are reliably identified at all epochs; all components
are effectively stationary except for component D, at ∼0.4mas from
the core, whose motion is however subluminal. The analysis of the
light curve shows two different states, with the source being brighter
and more variable in the first half of 2011 than in the second half.
The highest flux density is reached in February. A comparison with the
optical data reveals an increase of the V magnitude and of the
fractional polarization simultaneous with the enhancement of the radio
activity.
Description:
File table3 contains all the parameters about Gaussian components,
resulting from the model-fit analysis. For each component Flux density
(with uncertainties), radius (with uncertainties) and position angle
in polar coordinates of the component's center with respect to the
core, FWHM of the circular Gaussian component.
The other three files are FITS file from which we produced images in
Fig.1 (J1104NovBG207.FITS and J1104AprBm303.FITS), and the image in
Fig.3 that shows the gaussian components obtained model-fitting the
July image (J1104Jul_comp.FITS).
Objects:
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RA (2000) DE Designation(s)
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11 04 27.31 +38 12 31.8 Mrk 421 = LEDA 33452
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 62 141 Model-fit analysis details
list.dat 132 3 List of FITS files
fits/* . 3 Individual FITS files
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See also:
J/A+A/545/A117 : Monitoring of Mrk 421 at 15 and 24 GHz (Lico+, 2012)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 11 A11 "date" ObsDate Observation date
13- 18 A6 --- ExpCode Experiment code (AANNNa)
20- 23 A4 --- Comp ID Label of each component ("Core" or C1,...)
26- 30 F5.1 mJy Stot Flux density at 43GHz
34- 37 F4.1 mJy e_Stot Uncertainty on Stot
40- 43 F4.2 mas r ?=- Distance from the core
46- 49 F4.2 mas e_r Uncertainty on r
52- 56 F5.1 deg PA [-90/180]?=- Position angle of the component's
center with respect to the core (1)
59- 62 F4.2 mas a FWHM of the circular Gaussian component
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Note (1): The angle is measured from North through East.
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 24 E5.1 arcsec/pix Scale Scale of the image (0.02mas/pix)
26- 28 I3 pix Nx [301] Number of pixels along X-axis
29 A1 --- --- [x]
30- 32 I3 pix Ny [301] Number of pixels along Y-axis
34- 46 A13 --- FileName Name of FITS file in subdirectory fits
48-132 A85 --- Title Title of the file
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Acknowledgements:
Maria Grazia Blasi, mariagrazia.blasi87(at)gmail.com
(End) Maria Grazia Blasi [INAF, Bologna], Patricia Vannier [CDS] 03-Oct-2013