Issue |
Astron. Astrophys. Suppl. Ser.
Volume 122, Number 3, May I 1997
|
|
---|---|---|
Page(s) | 441 - 445 | |
DOI | https://doi.org/10.1051/aas:1997335 | |
Published online | 15 May 1997 |
Optical astrometry of Benchmark radio sources
IV. New results in the southern hemisphere
Departamento de Astronomía, Universidad de Chile. Casilla 36-D Santiago, Chile
Received:
11
June
1996
Accepted:
5
August
1996
Optical positions relative to the International Reference Stars
Catalogue (IRS), and therefore in the system of the FK5, have been obtained
for the optical counterparts of 40 compact extragalactic radio sources south
of δ ∼ +6°. Many of these sources are being considered as
possible Benchmark objects for the establishment of a quasi-inertial unified
radio/optical reference frame. Precision levels as good as 0.1 in both
coordinates were achieved. A comparison with VLBI radio positions available
for these sources is presented. We give new evidence for the existence of an
offset in the origin of right ascension between the radio and optical
reference frames as defined at present.
Key words: astrometry / reference systems
© European Southern Observatory (ESO), 1997