J/MNRAS/466/1567 Sou323 ICRF reference sample (Liu+, 2017)
Test of source selection for constructing a more stable and uniform
celestial reference frame.
Liu N., Liu J.-C., Zhu Z.
<Mon. Not. R. Astron. Soc., 466, 1567-1574 (2017)>
=2017MNRAS.466.1567L 2017MNRAS.466.1567L (SIMBAD/NED BibCode)
ADC_Keywords: Fundamental catalog ; Positional data ; VLBI
Keywords: catalogues - astrometry - reference systems
Abstract:
We aim to evaluate the possibility of improving the International
Celestial Reference System realization starting from the ICRF2
catalogue by investigating the coordinate time series of radio sources
observed by the very long baseline interferometry between 1979 and
2016. Sources with long observational history are selected as the
candidates and the least-squares fits with special handling of the
weights are performed to derive the linear drifts of the source
coordinates. Then the sources are sorted, based on the normalized
linear drift (i) over the whole sky, and (ii) in four homolographic
areas divided by declinations. The axial stability of the reference
system and sky distribution defined by the selected sources are
evaluated, which are acted as the criterion for the final source
lists. With our improved source selection scheme, two groups of
sources are proposed and considered suitable for defining a more
stable and homogeneous celestial reference system compared to the
second version of the current International Celestial Reference Frame
(ICRF2). The number of sources in the final lists are 323 and 294,
respectively, and the global rotations of the axes derived from
apparent motion of the sources are about two times better th
Description:
With the coordinate time series over 30yr, some of ICRF2 defining
appear to be unstable and not suitable for defining a celestial frame.
We have applied an improved selection scheme to pick out suitable
sources as candidates.
Finally, two sets of sources that show improved axial stability and
sky distribution are recommended (Sou323 and Sou294).
Only Sou323 is available.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 101 323 Time-series statistical information of sources
in Sou323
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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- 4 A4 --- --- [ICRF]
6- 21 A16 --- ICRF ICRF designation (JHHMMSS.s+DDMMSS)
24- 31 A8 --- IERS IERS source name (HHMM+DDd, B1950)
36- 39 F4.2 --- pm/e_pm Ratio of proper motion on proper motion error
42- 47 F6.1 uas/yr dpmRA* Liner drift in pmRA*cosDE
50- 55 F6.1 uas/yr dpmDE Liner drift in pmDE
60- 63 F4.2 mas WdevRA* Weighted standard deviation in RA*cosDE
68- 71 F4.2 mas WdevDE Weighted standard deviation in DE
76- 79 F4.2 mas WAdevRA* Weighted Allan deviation in RA*cosDE
84- 87 F4.2 mas WAdevDE Weighted Allan deviation in DE
92- 95 F4.1 yr Tobs Observation span
98-101 I4 --- Nses Number of seasons
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 15-Oct-2019