J/AJ/162/21 PS1 photometry of 2863 ICRF3 quasars (Berghea+, 2021)
Optical variability of ICRF3 quasars in the Pan-STARRS 3π survey with
functional principal component analysis.
Berghea C.T., Makarov V.V., Quigley K., Goldman B.
<Astron. J., 162, 21-21 (2021)>
=2021AJ....162...21B 2021AJ....162...21B (SIMBAD/NED BibCode)
ADC_Keywords: QSOs; Radio sources; Photometry, infrared; Optical
Keywords: Space astrometry; Radio source catalogs; Quasars
Abstract:
We make use of individual (epoch) detection data from the Pan-STARRS
"3π" survey for 2863 optical ICRF3 counterparts in the five
wavelength bands g, r, i, z, and y, published as part of the Data
Release 2. A dedicated method based on the Functional Principal
Component Analysis is developed for these sparse and irregularly
sampled data. With certain regularization and normalization
constraints, it allows us to obtain uniform and compatible estimates
of the variability amplitudes and average magnitudes between the
passbands and objects. We find that the starting assumption of
affinity of the light curves for a given object at different
wavelengths is violated for several percent of the sample. The
distributions of rms variability amplitudes are strongly skewed toward
small values, peaking at ∼0.1mag with tails stretching to 2mag.
Statistically, the lowest variability is found for the r band and the
largest for the reddest y band. A small "brighter-redder" effect is
present, with amplitudes in y greater than amplitudes in g in 57% of
the sample. The variability versus redshift dependence shows a strong
decline with z toward redshift 3, which we interpret as the time
dilation of the dominant time frequencies. The colors of radio-loud
ICRF3 quasars are correlated with redshift in a complicated, wavy
pattern governed by the emergence of brightest emission lines within
the five passbands.
Description:
We analyze astrometric and photometric epoch data collected by the
Pan-STARRS DR2 (PS1-DR2) for a sample of 2863 International Celestial
Reference Frame (ICRF3) radio sources. PS1 is a wide-field imaging
system, with a 1.8m telescope and 7.7deg2 field of view, located on
the summit of Haleakala in the Hawaiian island of Maui. The 1.4Gpixel
camera consists of 60 CCDs with pixel size of 0.256arcsec. It uses
five filters (gP1, rP1, iP1, zP1, and yP1, hereafter grizy).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 59 13384 Catalog of ICRF3 variability parameters
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See also:
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
J/AJ/121/2308 : Sloan Digital Sky Survey quasar photometry (Richards+, 2001)
J/ApJ/633/638 : Variable quasar sample from SDSS (Wilhite+, 2005)
J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)
J/ApJ/698/895 : Variations in QSOs optical flux (Kelly+, 2009)
J/ApJ/835/L30 : Dislodged AGNs (Makarov+, 2017)
J/MNRAS/467/L71 : Significance of VLBI/Gaia position offsets (Petrov+, 2017)
J/ApJ/873/132 : ICRF3 radio-loud quasars with Gaia DR2 data (Makarov+, 2019)
J/MNRAS/485/1822 : AGN core shift measurements (Plavin+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- IVS IVS ID, IVS BHHMM+DDd
10- 12 I3 --- Nobs [6/150] Total number observations used in 5 filters
14- 17 F4.2 --- Scale [0.03/1.65] Scale, Γ
19- 23 F5.3 mag MAD [0/0.15] post-fit residual
25- 25 A1 --- Filt PS1 filter
27- 32 F6.3 mag mag [5.99/23.4] FPCA-fitted mean magnitude
34- 39 F6.3 mag AV [-3.04/60] FPCA-fitted amplitude of variability
41- 46 F6.3 mag momag [12.5/22.4] Median observed median magnitude
48- 52 F5.3 mag 3MAD [0.001/4.85] observed dispersion, MAD times 3
54- 59 F6.1 --- SNR [-60/7932] Signal-to-noise ratio
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 08-Nov-2021