J/A+A/611/A52 Gaia DR1 QSO magnitude (Taris+, 2018)
Variability of extragalactic sources: its contribution to the link
between ICRF and the future Gaia Celestial Reference Frame.
Taris F., Damljanovic G., Andrei A., Souchay J. Klotz, A., Vachier F.
<Astron. Astrophys. 611, A52 (2018)>
=2018A&A...611A..52T 2018A&A...611A..52T (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Photometry, RI
Keywords: reference systems - quasars: general - galaxies: photometry -
methods: data analysis
Abstract:
The first release of the Gaia catalog is available since 14 September
2016. It is a first step in the realization of the future Gaia
reference frame. This reference frame will be materialized by the
optical positions of the sources and will be compared with and linked
to the International Celestial Reference Frame, materialized by the
radio position of extragalactic sources.
As in the radio domain, it can be reasonably postulated that quasar
optical flux variations can alert us to potential changes in the
source structure. These changes could have important implications for
the position of the target photocenters (together with the evolution
in time of these centers) and in parallel have consequences for the
link of the reference systems.
A set of nine optical telescopes was used to monitor the magnitude
variations, often at the same time as Gaia, thanks to the Gaia
Observation Forecast Tool. The Allan variances, which are statistical
tools widely used in the atomic time and frequency community, are
introduced.
Description:
The files table3.dat contains the name of the sources together with
the location of the telescope used, their observation dates in Julian
day, the magnitudes and their corresponding uncertainties.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 64 60 List of observed QSOs
table3.dat 43 3958 List of observations in R filter
from 2013 to 2016
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See also:
I/323 : International Celestial Reference Frame 2, ICRF2 (Ma+, 2009)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name QSO name (IERS BHHMM+DDd)
16- 27 A12 --- OCA Target name for OCA observation in table3
29- 31 I3 --- o_OCA ? Number of OCA measuements in table3
33- 44 A12 --- TJO Target name for TJO observation in table3
46- 47 I2 --- o_TJO ? Number of TJO measuements in table3
49- 61 A13 --- VBRL Target name for VBRL observation in table3
63- 64 I2 --- o_VBRL ? Number of VBRL measuements in table3
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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- 13 A13 --- Obs Target name (1)
17- 29 F13.5 --- JD Julian date of observation
31- 36 F6.3 mag Rmag R magnitude
39- 43 F5.3 mag e_Rmag rms uncertainty of the magnitude determination
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Note (1): The target name is composed by the telescope location where the image
has been obtained (OCA; Observatoire de la Cote d Azur;
TJO for Telescope Joan Oro; VBRL for Vidojevica-Belogradchik-Rozhen-LFOA) and
the target Id, as OCA_HHMM+DDd, TJO_HHMM+DDd or VBRL_HHMM+DDd.
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Acknowledgements:
Francois Taris, francois.taris(at)obspm.fr
(End) Francois Taris [Obs. Paris, France], Patricia Vannier [CDS] 29-Nov-2017