J/AJ/150/58 VLBI ICRF2 (Fey+, 2015)
The Second Realization of the International Celestial Reference Frame by Very
Long Baseline Interferometry.
Fey A.L., Gordon D., Jacobs C.S., Ma C., Gaume R.A., Arias E.F., Bianco G.,
Boboltz D.A., Bockmann S., Bolotin S., Charlot P., Collioud A.,
Engelhardt G., Gipson J., Gontier A.-M., Heinkelmann R., Kurdubov S.,
Lambert S., Lytvyn S., MacMillan D.S., Malkin Z., Nothnagel A., Ojha R.,
Skurikhina E., Sokolova J., Souchay J., Sovers O.J., Tesmer V., Titov O.,
Wang G., Zharov V.
<Astron. J., 150, 58 (2015)>
=2015AJ....150...58F 2015AJ....150...58F (SIMBAD/NED BibCode)
ADC_Keywords: Interferometry ; VLBI ; Positional data
Keywords: astrometry - catalogs - quasars: general - radio continuum: galaxies -
reference systems - techniques: interferometric
Abstract:
We present the second realization of the International Celestial
Reference Frame (ICRF2) at radio wavelengths using nearly 30 years of
Very Long Baseline Interferometry observations. ICRF2 contains precise
positions of 3414 compact radio astronomical objects and has a
positional noise floor of ∼40µas and a directional stability of the
frame axes of ∼10µas. A set of 295 new "defining" sources was
selected on the basis of positional stability and the lack of
extensive intrinsic source structure. The positional stability of
these 295 defining sources and their more uniform sky distribution
eliminates the two greatest weaknesses of the first realization of the
International Celestial Reference Frame (ICRF1). Alignment of ICRF2
with the International Celestial Reference System was made using 138
positionally stable sources common to both ICRF2 and ICRF1. The
resulting ICRF2 was adopted by the International Astronomical Union as
the new fundamental celestial reference frame, replacing ICRF1 as of
2010 January 1.
Description:
We present the second realization of the International Celestial
Reference Frame (ICRF2) at radio wavelengths using nearly 30 years of
Very Long Baseline Interferometry observations. The earliest
observations used are from 1979 August and the latest are from 2009
March. ICRF2 consists of accurate positions of 295 new "defining"
sources and positions of 3119 additional compact radio sources to
densify the frame. ICRF2 has more than 5 times as many sources as
ICRF1 (Ma et al. 1997, cat. I/251), is roughly 5-6 times more
accurate, and is nearly twice as stable in the orientation of its
axes.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 130 295 Coordinates of the 295 International Celestial
Reference Frame (ICRF2) "defining" sources
table6.dat 130 922 Coordinates of 922 ICRF2 non-Very Long Baseline
Array (VLBA) Calibrator Surveys (VCS) sources
table7.dat 130 2197 Coordinates of 2197 ICRF2 (VCS-only) sources
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See also:
I/323 : International Celestial Reference Frame 2, ICRF2 (Ma+, 2009)
J/AJ/136/580 : Sixth VLBA calibrator survey: VCS6 (Petrov+, 2008)
J/AJ/131/1872 : Fourth VLBA calibrator survey: VCS4 (Petrov+, 2006)
J/AJ/130/2529 : Southern ICRF sources 8.4GHz VLBI observations (Ojha+, 2005)
J/AJ/129/1163 : Third VLBA calibrator survey: VCS3 (Petrov+, 2005)
J/AJ/127/3609 : VLBI observations of southern ICRF sources (Ojha+, 2004)
J/AJ/127/3587 : VLBI ICRF. II (Fey+, 2004)
J/ApJS/141/13 : VLBA calibrator survey: VCS1 catalog (Beasley+, 2002)
J/ApJS/128/17 : VLBA obs. of radio reference frame sources. III. (Fey+, 2000)
J/MNRAS/445/845 : Implications of Galactic aberration for CRF (Malkin, 2014)
Byte-by-byte Description of file: table[567].dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [ICRF]
6- 21 A16 --- ICRF2 Designation in International Celestial Reference
Frame (ICRF2) (1)
23- 30 A8 --- IERS Designation in International Earth Rotation and
Reference Systems Service (IERS) (2)
32- 33 I2 h RAh Hour of Right Ascension (J2000)
35- 36 I2 min RAm Minute of Right Ascension (J2000)
38- 48 F11.8 s RAs Second of Right Ascension (J2000)
50 A1 --- DE- Sign of the Declination (J2000)
51- 52 I2 deg DEd Degree of Declination (J2000)
54- 55 I2 arcmin DEm Arcminute of Declination (J2000)
57- 66 F10.7 arcsec DEs Arcsecond of Declination (J2000)
68- 77 F10.8 s e_RAs Uncertainty in RAs
79- 87 F9.7 arcsec e_DEs Uncertainty in DEs
89- 94 F6.3 --- Corr [-1/1] Correlation between estimates of RA and DE
96-102 F7.1 d MJD [47002.2/54818.7] Modified Julian date of
observation mean (JD-2400000.0)
104-110 F7.1 d MJD0 [44090.1/54818.7] Modified Julian date of
observation start (JD-2400000.0)
112-118 F7.1 d MJD1 [48162.4/54907.9] Modified Julian date of
observation end (JD-2400000.0)
120-123 I4 --- Nexp [1/4068] Number of experiments
125-130 I6 --- Nobs [3/337322] Number of observations
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Note (1): Constructed from the source coordinates with the format
ICRF JHHMMSS.s+DDMMSS or ICRF JHHMMSS.s-DDMMSS; they follow the
recommendations of the IAU Task Group on Designations.
Note (2): Previously constructed from B1950 coordinates; the complete format,
including acronym and epoch in addition to the coordinates, is
IERS BHHMM+DDd or IERS BHHMM-DDd.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 18-Jan-2016