J/A+A/587/A112 Long term R and V band monitoring of AGN (Taris+, 2016)
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 J., Roland A., Klotz A., Vachier S., Souchay J.
<Astron. Astrophys. 587, A112 (2016)>
=2016A&A...587A.112T 2016A&A...587A.112T (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Active gal. nuclei ; Magnitudes
Keywords: reference systems - astrometry - quasars: general
Abstract:
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.
Description:
The files table5.dat and table6.dat contain the name of the sources,
their observation dates, the location of the telescope used, the
filter names, the magnitudes and their corresponding uncertainties.
The observations have been carried out between 2011 and 2015 with the
TAROT Telescopes.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 71 14 Studied sources
table5.dat 50 4625 List of observations in R filter from 2011 to 2015
table6.dat 50 4756 List of observations in V filter from 2011 to 2015
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Byte-by-byte Description of file: sources.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name IERS name (BHHMM-DDd)
11- 18 A8 --- MType Object type
20- 29 F10.6 deg RAdeg LQAC2 right ascension (J2000)
31- 40 F10.6 deg DEdeg LQAC2 declination (J2000)
42- 46 F5.2 mag <Rmag> Average Cousins R magnitude
48- 51 F4.2 mag e_<Rmag> rms uncertainty on <Rmag>
53- 57 F5.2 mag <Vmag> Average Cousins V magnitude
59- 62 F4.2 mag e_<Vmag> rms uncertainty on <Vmag>
64- 71 F8.6 --- z Redshift
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Byte-by-byte Description of file: table5.dat table6.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Target Target name, BHHMM+DDd-F-OOO (1)
17- 30 F14.6 --- JD Julian date of observation
32- 38 F7.4 --- mag Magnitude in Filter
40- 44 F5.3 --- rms Uncertainty of the magnitude determination
46 A1 --- Filt [RV] Filter (V or R Cousins)
47 A1 --- --- [-]
48- 50 A3 --- Obs Observatory code (ESO or OCA)
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Note (1): The target name is composed by the target Id, the filter used
(R or V Cousins) and the telescope location where the image has been obtained
(ESO; European Southern Observatory, OCA; Observatoire de la Cote d Azur).
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Acknowledgements:
Francois Taris, francois.taris(at)obspm.fr
(End) Francois Taris [Obs. Paris, France], Patricia Vannier [CDS] 15-Dec-2015