J/AJ/133/2357 Relativistic jets in the RRFID database (Piner+, 2007)
Relativistic jets in the Radio Reference Frame Image Database.
I. Apparent speeds from the first 5 years of data.
Piner B.G., Mahmud M., Fey A.L., Gospodinova K.
<Astron. J., 133, 2357-2388 (2007)>
=2007AJ....133.2357P 2007AJ....133.2357P
ADC_Keywords: Radio sources ; QSOs ; Active gal. nuclei ; Morphology
Keywords: galaxies: active - galaxies: jets - radio continuum: galaxies
Abstract:
We present the results of an analysis of relativistic jet apparent
speeds from VLBI images in the Radio Reference Frame Image Database
(RRFID). The images are snapshot VLBI images at 8 and 2GHz using the
VLBA, plus up to 10 additional antennas that provide global VLBI
coverage. We have analyzed the 8GHz images from the first 5 years of
the database (1994-1998), for all sources observed at three or more
epochs during this time range. This subset comprises 966 images of 87
sources. The sources in this subset have an average of 11 epochs of
observation over the years 1994-1998, with the best-observed sources
having 19 epochs. About half of the sources in this RRFID kinematic
survey have not been previously studied with multi-epoch VLBI
observations. We have measured apparent speeds for a total of 184 jet
components in 77 sources, of which the best-measured 94 component
speeds in 54 sources are used in the final analysis.
Description:
Observations were made using the 10 antennas of the VLBA of the
National Radio Astronomy Observatory (NRAO),7 along with an array
consisting of up to seven geodetic antennas.
Eight intermediate frequencies (IFs) were recorded simultaneously,
each 8MHz wide, with four at S band (2.24, 2.27, 2.36, and 2.38GHz)
and four at X band (8.41, 8.48, 8.79, and 8.90GHz) for a total
bandwidth of 32MHz in each frequency band.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 32 87 Sources in the RRFID kinematic survey
table3.dat 77 2579 Gaussian Models
table4.dat 44 184 Apparent Component Speeds
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See also:
J/AJ/110/880 : Radio reference frame (Johnston+ 1995)
J/ApJS/128/17 : VLBA obs. of radio reference frame sources. III. (Fey+, 2000)
J/AJ/127/3609 : VLBI observations of southern ICRF sources (Ojha+, 2004)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- IERS IAU name (HHMM+DDd, IERS BHHMM+DDd in Simbad)
10- 17 A8 --- OName Other name
19- 20 I2 --- Nep Number of epochs observed
22- 26 A5 --- Class Optical class (1)
28- 32 F5.3 --- z ?=- Redshift
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Note (1): Optical class from Veron-Cetty & Veron (2003, Cat. VII/235)
as follows:
Q = quasar
B = BL Lac object
G = galaxy
HP = high polarization
U = unidentified
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- IERS IAU name (HHMM+DDd, IERS BHHMM+DDd in Simbad)
10- 15 F6.3 Jy S Component flux density at 8GHz
17- 22 F6.3 mas Rad Radial position of component center
24- 29 F6.1 deg PA [-180/180] Position angle of component center (1)
31- 35 F5.3 mas a Full-width at half maximum size of component
37- 41 F5.3 --- b/a Axial ratio of component
43- 47 F5.1 deg PAMA Position angle of major axis; if an elliptical
component (1)
49 I1 --- Type [1] DIFMAP component type (1 = Gaussian)
51- 57 F7.2 yr Epoch Epoch of observation
59- 60 I2 --- Comp ?=99 Component ID (2)
62- 66 F5.2 mas aBeam Beam major axis (3)
68- 71 F4.2 mas bBeam Beam minor axis (3)
73- 77 F5.1 deg PABeam Beam position angle (1,3)
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Note (1): All position angles are measured from north through east.
Note (2): The core is identified as component 0, and other jet components
are identified as components 1-6, from the outermost component inward.
An ID of '99' indicates a flagged component not used in the analysis.
Note (3): Beam parameters are computed using natural weighting specifically
'uvweight = 0,-1' in DIFMAP.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- IERS IAU name (HHMM+DDd, IERS BHHMM+DDd in Simbad)
10 I1 --- Comp [1/6] Component ID
12- 17 F6.3 mas/yr mu Proper motion
19- 23 F5.3 mas/yr e_mu Uncertainty in mu
25- 30 F6.2 --- beta Apparent speed in units of the speed of light
32- 36 F5.2 --- e_beta Uncertainty in beta
38 I1 --- xi The ξ value (1)
40 A1 --- DC [Y/N] Distinct component (2)
42 A1 --- Qual [EFGP] Overall quality code (3)
44 A1 --- 2cm [Y/N] In a 2cm (15GHz) survey (4)
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Note (1): Error bars on component positions were computed as a fraction
1/2ξ of the beam size, where ξ was a function of the average
flux of the component, see Section 4.1.
Note (2): Whether or not the component is a distinct feature. Y=Yes, N=No.
Note (3): Criteria definitions as follows:
E = Excellent; for motions that satisfy all three of the criteria.
G = Good; for motions that satisfy any two of the criteria.
F = Fair; for motions that satisfy only one of the criteria.
P = Poor; for motions that do not satisfy any of the criteria, or for
motions where the uncertainty in the fitted proper motion is
>0.15mas/yr (except for the ≥5σ cases mentioned in the text.
Note (4): Whether or not the source has an apparent speed measured from the
2cm survey (Kellermann et al., 2004, cat. J/ApJ/609/539). Y=Yes, N=No.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 01-Apr-2009