J/A+A/544/A28ivo://CDS.VizieR/J/A+A/544/A28doi:10.26093/cds/vizier.35440028CDSOdell A.2017-06-21T08:22:43Z2012-07-27T09:56:13ZCDS support team

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

cds-question@unistra.frvariable-starsvisible-astronomybroad-band-photometrymedium-band-photometryFor the past 25 years, BW Vulpeculae has been the topic of period analyses centered on a secular period change with a periodic variation superposed, presumed to be due to light time effects in a binary system. According to this paradigm, one would expect what seems like a period increase of about 0.5s during or soon after the year 2001. I have continued photometric monitoring through the year 2012, adding 40 new timings of maximum and minimum light. This expected change in period did not occur, which rules out that interpretation of the period variation. As of 2012, the observed timings are about two hours early compared to those predicted by the quadratic ephemeris, but are very close to those predicted by the linear ephemeris. In fact, the period has remained constant for the last 32 years, indicating that the previous epochs of constant period are almost certainly the correct interpretation, though the cause of the period changes is still not clear. Continued photometric monitoring of BW Vul leads to the conclusion that the period changes are abrupt, followed by epochs of constant period lasting between 12 and at least 32 years.2012A&A...544A..28Ohttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/544/A28CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/544/A28https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/544/A28http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/544/A28https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/544/A28https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/544/A28http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/544/A28GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap2.7751437095755416e-19 6.118840631666147e-19OpticaldefaultJ/A+A/544/A28/stromgrnDifferential magnitudes (BW Vul - HR 7996) in Stromgren b and y filtersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDb? Heliocentric Julian Day for b banddtime.epoch;pos.heliocentricdoublenullablePhaseb? Phase for b band (G1)time.phasefloatnullableDbmag? Differential Stromgren b magnitudemagphot.mag;em.opt.B;arith.difffloatnullableHJDy? Heliocentric Julian Day for y banddtime.epoch;pos.heliocentricdoublenullablePhasey? Phase for y band (G1)time.phasefloatnullableDymag? Differential Stromgren y magnitudemagphot.mag;em.opt.V;arith.difffloatnullableJ/A+A/544/A28/johnsonDifferential magnitudes (BW Vul - HR 7996) in Johnson V, B, and U filters (not all are included on each night)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDV? Heliocentric Julian Day for V banddtime.epoch;pos.heliocentricdoublenullablePhaseV? Phase for V band (G1)time.phasefloatnullableDVmag? Differential Johnson V magnitudemagphot.mag;em.opt.V;arith.difffloatnullableHJDB? Heliocentric Julian Day for B banddtime.epoch;pos.heliocentricdoublenullablePhaseB? Phase for B band (G1)time.phasefloatnullableDBmag? Differential Johnson B magnitudemagphot.mag;em.opt.B;arith.difffloatnullableHJDU? Heliocentric Julian Day for U banddtime.epoch;pos.heliocentricdoublenullablePhaseU? Phase for U band (G1)time.phasefloatnullableDUmag? Differential Johnson U magnitudemagphot.mag;em.opt.U;arith.difffloatnullableJ/A+A/544/A28/cometDifferential magnitudes (BW Vul - HR 7996) in three comet continuum filtersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDbc? Heliocentric Julian Day for blue banddtime.epoch;pos.heliocentricdoublenullablePhasebc? Phase for blue band (G1)time.phasefloatnullableDbcmag? Differential blue comet continuum magnitude 4450/4467{AA}magphot.mag;arith.difffloatnullableHJDgcHeliocentric Julian Day for green banddtime.epoch;pos.heliocentricdoublePhasegcPhase for green band (G1)time.phasefloatDgcmagDifferential green comet continuum magnitude 5260/5256{AA}magphot.mag;arith.difffloatHJDrc? Heliocentric Julian Day for red banddtime.epoch;pos.heliocentricdoublenullablePhaserc? Phase for red band (G1)time.phasefloatnullableDrcmag? Differential red comet continuum magnitude 7128/7158{AA}magphot.mag;arith.difffloatnullable