J/AJ/154/231 Multi-epoch multi-band photometry of B1-392 (Saha+, 2017)
A hybrid algorithm for period analysis from multiband data with sparse and
irregular sampling for arbitrary light-curve shapes.
Saha A., Vivas A.K.
<Astron. J., 154, 231 (2017)>
=2017AJ....154..231S 2017AJ....154..231S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Photometry, ugriz
Keywords: methods: data analysis - stars: variables: general -
techniques: miscellaneous
Abstract:
Ongoing and future surveys with repeat imaging in multiple bands are
producing (or will produce) time-spaced measurements of brightness,
resulting in the identification of large numbers of variable sources
in the sky. A large fraction of these are periodic variables:
compilations of these are of scientific interest for a variety of
purposes. Unavoidably, the data sets from many such surveys not only
have sparse sampling, but also have embedded frequencies in the observing
cadence that beat against the natural periodicities of any object under
investigation. Such limitations can make period determination ambiguous
and uncertain. For multiband data sets with asynchronous measurements
in multiple passbands, we wish to maximally use the information on
periodicity in a manner that is agnostic of differences in the
light-curve shapes across the different channels. Given large volumes
of data, computational efficiency is also at a premium. This paper
develops and presents a computationally economic method for determining
periodicity that combines the results from two different classes of
period-determination algorithms. The underlying principles are
illustrated through examples. The effectiveness of this approach for
combining asynchronously sampled measurements in multiple observables
that share an underlying fundamental frequency is also demonstrated.
Description:
The data are from a multiband study of variable stars toward the Galactic
bulge, using imaging data with the DECam instrument (Flaugher et al.
2015AJ....150..150F 2015AJ....150..150F) on the Blanco 4 m telescope at CTIO. Multiband
(DECam bands u,g,r,i and z) multi-epoch observations of one of the
variables are listed in Table 1. There are 58 well-measured epochs in u,
68 in g, 69 in r, 94 in i, and 81 in z. This object, labeled B1-392 in
the DECam study, was observed and reported by Soszynski et al. (2014,
J/AcA/64/177) from the OGLE project as OGLE-BLG-RRLYR-11078, and shown
to be an ab-type RR Lyrae star with period P=0.5016240 days. The OGLE time
coverage is much more extensive than for our DECam data, and their derived
period is expected to be very reliable. The DECam data include observations
of a few nights in each of 2013 May, June, and August, followed by parts of
three nights in 2015 February. During the 2013 nights, up to four
observations were made on a night, covering a span of up to 7 hr. This
is thus an excellent real-world example of sparse sampling infected
with periodic patterns: diurnal, lunation, and a nearly two-year gap.
Objects:
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RA (ICRS) DE Designation(s)
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18 01 33.92 -29 07 14.6 B1-392 = OGLE BLG-RRLYR-11078
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 28 370 Multi-epoch multi-band photometry of B1-392
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See also:
II/213 : OGLE Galactic Bulge periodic variables (Udalski+ 1996)
J/ApJ/651/197 : OGLE Galactic Bulge fundamental-mode RR Lyrae (Collinge+, 2006)
J/ApJ/708/717 : Light curve templates of RR Lyrae stars (Sesar+, 2010)
J/AcA/61/1 : VI light curves of Galactic Bulge RR Lyrae (Soszynski+, 2011)
J/AcA/64/177 : VI light curves of Galactic Bulge RR Lyrae (Soszynski+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 F13.7 d HJD Heliocentric Julian Date (HJD-2400000.0)
15- 20 F6.3 mag omag [21.517/28.203] Instrumental CTIO/DECam magnitude
with common zeropoint
22- 26 F5.3 mag e_omag [0.01/0.259] rms uncertainty in the magnitude
28 A1 --- Filt [ugriz] Passband filter name
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 30-Jul-2018