J/ApJ/817/73 QSOs and RR Lyrae in Pan-STARRS1 3π Data (Hernitschek+ 2016)
Finding, Characterizing, and Classifying variable sources in multi-epoch sky
surveys: QSOs and RR Lyrae in PS1 3π data
Hernitschek N., Schlafly E.F., Sesar B., Rix H.-W., Hogg D.W., Ivezic Z.,
Grebel E.K., Bell E.F., Martin N.F., Burgett W.S., Flewelling H.,
Hodapp K.W., Kaiser N., Magnier E.A., Metcalfe N., Wainscoat R.J., Waters C.
<Astrophys. J., 817, 73 (2016)>
=2016ApJ...817...73H 2016ApJ...817...73H
ADC_Keywords: Surveys ; Stars, variable ; QSOs
Description:
In area and depth, the Pan-STARRS1 (PS1) 3π survey is unique among
many-epoch, multi-band surveys and has enormous potential for the
all-sky identification of variable sources. PS1 has observed the sky
typically seven times in each of its five bands (grizy) over 3.5
years, but unlike SDSS, not simultaneously across the bands. We
developed a new approach for quantifying statistical properties of
non-simultaneous, sparse, multi-color light curves through light curve
structure functions, effectively turning PS1 into a ∼35-epoch
survey. We use this approach to estimate variability amplitudes and
timescales for point sources brighter than rP1=21.5 mag in the
survey. On this basis we provide a catalog of all likely variable
point sources and likely QSOs in PS1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 74 2 List of available catalogs
catpv3.dat 124 76804905 Catalog of variable sources in PS1 3π, with
PV3 version
catpv3.fits 2880 1600105 Catalog of variable sources in PS1 3π, with
PV3 version, fits version
catalog.dat 111 25409009 The catalog of variable sources in PS1 3π
table4.fits 2880 529357 The catalog of variable sources in PS1 3π,
FITS table (table4 of the paper)
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- FileName Name of the catalog
13- 20 I8 --- Nsources Number of sources
22- 74 A53 --- Title Title of the file
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Byte-by-byte Description of file: catpv3.dat
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Bytes Format Units Label Explanations
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1- 11 F11.7 deg RAdeg Right ascension (J2000) (RAdeg)
13- 23 F11.7 deg DEdeg Declination (J2000) (DECdeg)
25- 36 E12.6 --- chi2 [-7/26040] Variability quantity χ2-hat,
(chi2_hat) (G1)
38- 43 F6.4 --- omega [0.01/3.16] Amplitude parameter (omega_best) (G2)
45- 51 F7.2 --- tau [0.04/5000] Timescale parameter (tau_best) (G2)
53- 61 F9.4 mag gmag ?=9999.9902 mean gP1 (errorweightedmeanmag_g)
63- 71 F9.4 mag rmag ?=9999.9902 mean rP1 (errorweightedmeanmag_r)
73- 81 F9.4 mag imag ?=9999.9902 mean iP1 (errorweightedmeanmag_i)
83- 91 F9.4 mag zmag ?=9999.9902 mean zP1 (errorweightedmeanmag_z)
93-101 F9.4 mag ymag ?=9999.9902 mean yP1 (errorweightedmeanmag_y)
103-112 F10.4 mag W2 ?=-9999.9902 WISE W2 magnitude (W2)
114-118 F5.3 --- pQSO [0/1] Probability of QSO pQSO (p_QSO)
120-124 F5.3 --- pRRL [0/1] Probability of RR Lyr pRRL (p_RRLyrae)
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Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
-------------------------------------------------------------------------------
1- 11 F11.7 deg RAdeg Right ascension, J2000 (RAdeg)
13- 23 F11.7 deg DEdeg Declination J2000 (DECdeg)
25- 36 E12.5 --- chi2 [-4/106570] Variability quantity χ2-hat,
(chi2_hat) (G1)
38- 43 F6.4 mag omega [0.01/3.16] amplitude parameter (omega_best) (G2)
45- 51 F7.2 d tau [0.04/5000] timescale parameter (tau_best) (G2)
53- 59 F7.4 mag gmag ?=- mean gP1 (errorweightedmeanmag_g)
61- 67 F7.4 mag rmag ?=- mean rP1 (errorweightedmeanmag_r)
69- 75 F7.4 mag imag ?=- mean iP1 (errorweightedmeanmag_i)
77- 83 F7.4 mag zmag ?=- mean zP1 (errorweightedmeanmag_z)
85- 91 F7.4 mag ymag ?=- mean yP1 (errorweightedmeanmag_y)
93- 98 F6.3 mag W12 [-2.8/6.7]?=- WISE W1-W2 color (W12)
100-104 F5.3 --- pQSO [0/1] Probability of QSO pQSO (p_QSO)
106-110 F5.3 --- pRRL [0/1] Probability of RR Lyr pRRL (p_RRLyrae)
111 A1 --- fd [*] Flag (*) indicating 2 solutions (G3)
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Global notes:
Note (G1): the variability is defined by Eq.(1):
χ2 = [ χ2source - Ndof ] / sqrt(2.Ndof)
Ndof = degrees of freedom N - n, where
N = number of photometric points in all bands
n = number of filters
χ2source = quadratic sum of normalized differences
of all photometric points for one object across all bands
Note (G2): best fit structure function parameters of the damped random walk
(DRW) function:
ω = r-band variability amplitude) on log-spaced grid
{tau } = decorrelation timescale parameter on log-spaced grid
Note (G3): Flag added at CDS to the 2742 sources having identical positions
but 2 solutions are given.
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Author's address:
Nina Hernitschek <hernitschek(at)mpia.de>
History:
* 03-May-2016: first version with accurate position (25411665 records):
NHqsorrlyraecandidatescatalog_highprecpos.fits
* 05-Aug-2016: version with duplicates fixed (25409009 records):
NHqsorrlyraecandidatescataloguniquehighprecpos.fits, where
- true duplicates are removed
- the few duplicates which are not removed are indeed different objects
in the database (usually same or very close RA,Dec but a different
obj_id that usually differs only by 1)
(End) Nina Hernitschek [MPIA Heidelberg] 25-Apr-2016