J/A+A/500/917ivo://CDS.VizieR/J/A+A/500/917doi:10.26093/cds/vizier.35000917CDSSzulagyi J.Kovacs G.Welch D.L.2017-07-04T07:08:04Z2009-08-18T16:08:51ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frvariable-starsmagellanic-cloudsphotometryBecause of the strong effect of systematics/trends in variable star observations, we apply the Trend Filtering Algorithm (TFA) to a subset of the MACHO database and search for variable stars. TFA has been applied successfully in planetary transit searches, where weak, short-lasting periodic dimmings are sought in the presence of noise and various systematics (due to, e.g., imperfect flat fielding, crowding, etc). These latter effects introduce colored noise in the photometric time series that can completely overwhelm the signal. By using a large number of available photometric time series of a given field, TFA utilizes the fact that the same types of systematics appear in several/many time series of the same field. As a result, we attempt to reproduce each target time series by a linear combination of templates, optimized by least-squares. After a signal has been identified in the residuals between the original time series and the systematics computed by TFA, we reconstruct the signal by employing the full model, including the signal, systematics and noise. We apply TFA to the brightest ~5300 objects from subsets of each of the MACHO Large Magellanic Cloud fields #1 and #79. We find that the Fourier frequency analysis performed on the original data detects some 60% of the objects as trend-dominated. This figure decreases essentially to zero after using TFA. In total, we detect 387 variables in the two fields, 183 of which would have remained undetected without using TFA. Where possible, we give preliminary classification of the variables found.2009A&A...500..917Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/500/917CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/247 : Variable Stars in the Large Magellanic Clouds (MACHO, 2001)J/A+A/313/841 : MACHO LMC No.1 microlensing event (Dominik+, 1996)J/AJ/114/326 : MACHO Variables V. (Alcock+ 1997)J/ApJ/542/257 : MACHO LMC first-overtone RR Lyrae (Alcock+, 2000)J/AJ/127/334 : MACHO LMC first-overtone RR Lyrae variables (Alcock+, 2004)J/ApJ/562/337 : High proper-motion stars from MACHO astrometry (Alcock+, 2001)J/AJ/124/2039 : LMC blue variable stars from MACHO (Keller+, 2002)J/ApJ/598/597 : Frequency analysis of fundamental-mode RR Lyrae (Alcock+ 2003)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/500/917https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/500/917http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/500/917https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/500/917https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/500/917http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/500/917GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/500/917/stars (Variable stars in the Macho fields 1 and 79)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/500/917/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/500/917/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/500/917/stars?GETtext/xml+votable180.050000true75.3323333-69.35230560.0055555555555555566/33077 33098 331203.322582951404819e-19 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/500/917?format=asciiOpticaldefaultJ/A+A/500/917/starsVariable stars in the Macho fields 1 and 79recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFldSimbad column added by the CDSobs.fieldintnullableNameName, HHMMSSss+DDMMSSsmeta.id;meta.maincharVmagAverage Johnson V magnitudemagphot.mag;em.opt.VfloatV-RcAverage Johnson V minus Cousins R colormagphot.color;em.opt.V;em.opt.RfloatFreqFrequency (1/P, where P is the dominant period) (1)d**-1em.freqdoubleSNRSignal-to-noise ratio (2)stat.snrfloatVTypeVariable type (4)meta.code;src.varcharTFA[0/1] Discovery type (3)meta.codeint_RASimbad column added by the CDSdegpos.eq.ra;meta.main_DESimbad column added by the CDSdegpos.eq.dec;meta.main