2016A&A...587A.112T


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST16:26:29

2016A&A...587A.112T - Astronomy and Astrophysics, volume 587A, 112-112 (2016/3-1)

Long-term R and V-band monitoring of some suitable targets for the link between ICRF and the future Gaia celestial reference frame.

TARIS F., ANDREI A., ROLAND J., KLOTZ A., VACHIER F. and SOUCHAY J.

Abstract (from CDS):

The Gaia astrometric mission of the European Space Agency was launched on December 2013. It will provide a catalog of 500 000 quasars. Some of these targets will be chosen to build an optical reference system that will be linked to the International Celestial Reference Frame (ICRF). The astrometric coordinates of these sources will have roughly the same uncertainty at both optical and radio wavelengths, and it is then mandatory to observe a common set of targets to build the link. In the ICRF, some targets have been chosen because of their pointlikeness. They are quoted as defining sources, and they ensure very good uncertainty about their astrometric coordinates. At optical wavelengths, a comparable uncertainty could be achieved for targets that do not exhibit strong astrophysical phenomena, which is a potential source of photocenter flickering. A signature of these phenomena is a magnitude variation at optical wavelengths. The goal of this work is to present the time series of 14 targets suitable for the link between the ICRF and the future Gaia Celestial Reference Frame. The observations have been done systematically by robotic telescopes in France and Chile once every two nights since 2011 and in two filters. These time series are analyzed to search for periodic or quasi-periodic phenomena that must be taken into account when computing the uncertainty about the astrometric coordinates. Two independent methods were used in this work to analyze the time series. We used the CLEAN algorithm to compare the frequency obtained to those given by the Lomb-Scargle method. It avoids misinterpreting the frequency peaks given in the periodograms. For the 14 targets we determine some periods with a confidence level above 90% in each case. Some of the periods found in this work were not previously known. For the others, we did a comparative study of the periods previously studied by others and always confirm their values. All the periods given by the two methods are in good agreement with the difference always below 7.9% in the worst case. Finally we also present the structure functions for our two sets of objects (BL Lac and Seyfert galaxies). For all but one target, we find variations that could be the signature of periodic or quasi-periodic phenomena. Our time series could allow to bring some constraints on astrophysical models that could explain such variations. Binary black hole system, instabilities in the jet or in the accretion disk, changes in the torus structure are some of these astrophysical phenomena. They must be kept in mind when evaluating the uncertainty about the astrometric position of the targets suitable for the link between reference systems in a conservative way.

Abstract Copyright:

Journal keyword(s): reference systems - astrometry - quasars: general

VizieR on-line data: <Available at CDS (J/A+A/587/A112): sources.dat table5.dat table6.dat>

Simbad objects: 26

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Number of rows : 26

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 Mrk 1501 Sy1 00 10 31.0058529490 +10 58 29.505989476   15.96 15.40 12.22   ~ 639 0
2 QSO B0109+224 BLL 01 12 05.8246825085 +22 44 38.786096536   16.00 15.66 15.47   ~ 295 2
3 PKS 0405-123 Sy1 04 07 48.4309594137 -12 11 36.660481492   15.09 14.86 14.7   ~ 469 1
4 QSO B0420-0127 QSO 04 23 15.80072776 -01 20 33.0654034   17.50 17.00 16.28   ~ 1053 3
5 8C 0716+714 BLL 07 21 53.4484901266 +71 20 36.362058601   15.5 14.17 14.27   ~ 1131 1
6 QSO J0738+1742 BLL 07 38 07.39374766 +17 42 18.9982302   16.76 16.22 15.78   ~ 896 1
7 QSO B0823-223 BLL 08 26 01.57293454 -22 30 27.2032544   16.11 16.20     ~ 182 1
8 ICRF J092703.0+390220 Sy1 09 27 03.0139516273 +39 02 20.847968628   17.17 17.00 16.486   ~ 932 1
9 Ton 469 Sy1 09 58 20.94963113 +32 24 02.2095353   15.88 15.78 15.51   ~ 394 1
10 CTS 10 Sy1 11 03 31.5267293120 -32 51 16.692763487   16.29 16.30 16.4   ~ 102 1
11 7C 1147+2434 BLL 11 50 19.2119754161 +24 17 53.834754764   16.26 15.74 15.80   ~ 245 1
12 6C 121520+302351 BLL 12 17 52.0819140772 +30 07 00.636792927   16.07 15.62 13.47   ~ 405 1
13 QSO B1216+0216 QSO 12 18 55.8054045523 +02 00 02.144277567   17.69 17.40     ~ 29 0
14 3C 273 BLL 12 29 06.6996828061 +02 03 08.598846466   13.05 14.830 14.11   ~ 5316 1
15 3C 279 QSO 12 56 11.1664521013 -05 47 21.531840471   18.01 17.75 15.87   ~ 2702 2
16 ICRF J130533.0-103319 Sy1 13 05 33.0149111397 -10 33 19.430590671   15.18 15.23 14.46   ~ 496 1
17 7C 1424+2401 BLL 14 27 00.3918388878 +23 48 00.035406946 14.52 14.34 14.95 14.5   ~ 286 1
18 Mrk 877 Sy1 16 20 11.2800014833 +17 24 27.514065981   15.79 15.39     ~ 247 0
19 3C 345 QSO 16 42 58.8100340220 +39 48 36.999540578   16.81 16.59 16.84   ~ 1552 2
20 QSO B1722+119 BLL 17 25 04.34087 +11 52 15.4688   16.29 15.77 14.45   ~ 164 1
21 8C 1803+784 BLL 18 00 45.6831135718 +78 28 04.017792333   16.4 16.4 15.46   ~ 660 1
22 4C 56.27 BLL 18 24 07.06837771 +56 51 01.4908371   18.9 18.4 16.48   ~ 438 1
23 ICRF J192748.4+735801 Sy1 19 27 48.4944745594 +73 58 01.571908984     15.5 15.11   ~ 491 2
24 QSO B2155-304 BLL 21 58 52.0651817803 -30 13 32.120657891   13.36 13.09 12.62   ~ 1561 1
25 QSO B2254+0727 BLL 22 57 17.30312249 +07 43 12.3024770   17.07 16.36     ~ 284 1
26 ICRF J230343.5-680737 Sy1 23 03 43.5650270994 -68 07 37.443084908   16.26 16.38 17.68   ~ 76 1

    Equat.    Gal    SGal    Ecl

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2020.07.08-16:26:29

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