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I/341 PMA Catalogue (Akhmetov+, 2017)
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The PMA Catalogue: 420 million positions and absolute proper motions.
Akhmetov V.S., Fedorov P.N., Velichko A.B., Shulga V.M.
<Mon. Not. R. Astron. Soc. 469, 763 (2017)>
=2017MNRAS.469..763A (SIMBAD/NED BibCode)
=2017yCat.1341....0A
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ADC_Keywords: Positional data ; Proper motions
Keywords: catalogues - astrometry - proper motions - reference systems -
Galaxy: kinematics and dynamics
Abstract:
We present a catalogue that contains about 420 million absolute proper
motions of stars. It was derived from the combination of positions
from Gaia DR1 and 2MASS, with a mean difference of epochs of about
15yr. Most of the systematic zonal errors inherent in the 2MASS
Catalogue were eliminated before deriving the absolute proper motions.
The absolute calibration procedure (zero-pointing of the proper
motions) was carried out using about 1.6 million positions of
extragalactic sources. The mean formal error of the absolute
calibration is less than 0.35mas/yr. The derived proper motions cover
the whole celestial sphere without gaps for a range of stellar
magnitudes from 8 to 21mag. In the sky areas where the extragalactic
sources are invisible (the avoidance zone), a dedicated procedure was
used that transforms the relative proper motions into absolute ones.
The rms error of proper motions depends on stellar magnitude and
ranges from 2-5mas/yr for stars with 10mag<G<17mag to 5-10mas/yr for
faint ones. The present catalogue contains the Gaia DR1 positions of
stars for the J2015 epoch. The system of the PMA proper motions does
not depend on the systematic errors of the 2MASS positions, and in the
range from 14 to 21mag represents an independent realization of a
quasi-inertial reference frame in the optical and near-infrared
wavelength range. The Catalogue also contains stellar magnitudes taken
from the Gaia DR1 and 2MASS catalogues. A comparison of the PMA proper
motions of stars with similar data from certain recent catalogues has
been undertaken.
Description:
The idea for creating the catalogue is very simple. The PMA catalogue
has been derived from a combination of two catalogues, namely 2MASS
and Gaia DR1. The difference of epochs of observations for these
catalogues is approximately 15 yr. The positions of objects in the
Gaia DR1 catalogue are referred to the reference frame, which is
consistent with ICRF to better than 0.1 mas for the J2015.0 epoch. The
positions of objects in 2MASS are referred to HCRF, which, as was
shown in Kovalevsky et al. (1997A&A...323..620K), is aligned with the
ICRF to within +/-0.6 mas at the epoch 1991.25 and is non-rotating
with respect to distant extragalactic objects to within +/-0.25mas/yr.
By comparing the positions of the common objects contained in the
catalogues, it is possible to determine their proper motions within
their common range of stellar magnitudes by dividing differences of
positions over the time interval between their observations. Formally,
proper motions derived in such a way are given in the ICRF system,
because the positions of both Gaia DR1 stars and those of 2MASS
objects (through Hipparcos/Tycho-2 stars) are given in the ICRF and
cover the whole sphere without gaps. We designate them further in this
paper as relative, with the aim of discriminating them from absolute
ones, which refer to the reference frame defined by the positions of
about 1.6 million galaxies from Gaia DR1.
After elimination of the systematic errors, the root-mean-squared
deviation of the coordinate differences of extended sources is about
200mas, and the mean number of galaxies inside each pixel is about
1300, so we expect the error of the absolute calibration to be
0.35mas/yr.
We compared the proper motions of common objects from PMA and from the
TGAS and UCAC4 catalogues. Knowing the mean-square errors of
(PMA-TGAS) and (PMA-UCAC4) proper motion differences in each
pixel, the appropriate errors in PMA vary from 2 to 10mas/yr,
depending on magnitude, which are consistent with the errors
calculated above.
In case of any problems or questions, please contact by e-mail
V.S. Akhmetov (akhmetovvs(at)gmail.com or akhmetov(at)astron.kharkov.ua).