J/A+A/574/A38ivo://CDS.VizieR/J/A+A/574/A38doi:10.26093/cds/vizier.35740038CDSOpitom C.Jehin E.Manfroid J.Hutsemekers D.Gillon M.Magain P.2017-06-13T11:08:49Z2015-01-21T07:42:39ZCDS support team

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

cds-question@unistra.frcometsspectroscopyWe report the results of the long-term narrowband photometry and imaging monitoring of comet C/2012 F6 (Lemmon) with the robotic TRAPPIST telescope (La Silla observatory). Observations covered 52 nights pre- and post-perihelion between December 11, 2012 and June 11, 2013. We followed the evolution of the OH, NH, CN, C_3_ and C_2_ production rates computed with the Haser model as well as the evolution of the A({theta})f_{rho}_ parameter as a proxy for the dust production. All five gas species display similar slopes for the heliocentric dependence. An asymmetry about perihelion is observed, the rate of brightening being steeper than the rate of fading. The chemical composition of the comet's coma is changing slightly along the orbit: the relative abundance of C_2_ to CN is decreasing for heliocentric distances larger than 1.4AU while the C_3_ to CN ratio is constant during our observations. The behavior of the dust is different from that of the gas, the slope of the heliocentric dependence becoming steeper in early February, correlated to a change of the visual lightcurve slope. However, the dust color does not vary during the observations. The application of several enhancement techniques on the images revealed structures in the CN, C3 and C2 images. These features imply the existence of one or several active zone(s) on the comet nucleus. The shape of the structures is similar in those three filters and changes from a roughly hourglass shape in December and January to a corkscrew shape in February and March. The structures in the continuum filters (sampling the dust) are not correlated to those observed for the gas. During several full nights in February, we observed changes in the CN and C2 structures repeating periodically due to the nucleus rotation, our derived rotational period being of 9.52+/-0.05 hours.2015A&A...574A..38Ohttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/574/A38CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/574/A38https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/574/A38http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/574/A38https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/574/A38https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/574/A38http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/574/A38GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/574/A38/obslogObservational circumstances of comet C/2012 F6 (Lemmon) (table2)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateStart date of the observations (UT) (YYYY MMM DD.dd)time.start;obscharEndEnd day of the observationtime.end;obsfloatr[-2/1.7] Heliocentric DistanceAUpos.distance;pos.heliocentricfloatDelta[0.99/2] Geocentric distance {Delta}AUpos.distance;pos.geocentricfloatHV[-25/25] Heliocentric Velocitykm/sspect.dopplerVeloc;pos.heliocentricfloatPhA[29/58] Phase Angledegpos.phaseAngfloatPA[149/300] Position Angledegpos.posAngfloatOH[1/12]? Number of observations in the OH filtermeta.numberintnullableNH[1/13]? Number of observations in the NH filtermeta.numberintnullableCN[1/25]? Number of observations in the CN filtermeta.numberintnullableC3[1/13]? Number of observations in the C_3_ filtermeta.numberintnullableC2[1/12]? Number of observations in the C_2_ filtermeta.numberintnullableUC[1/12]? Number of observations in the UC filtermeta.numberintnullableBC[1/12]? Number of observations in the BC filtermeta.numberintnullableGC[1/12]? Number of observations in the GC filtermeta.numberintnullableRC[1/12]? Number of observations in the RC filtermeta.numberintnullableB[1/14]? Number of observations in the B filtermeta.numberintnullableV[1/14]? Number of observations in the V filtermeta.numberintnullableR[1/14]? Number of observations in the R filtermeta.numberintnullableI[1/14]? Number of observations in the I filtermeta.numberintnullableJ/A+A/574/A38/qOH, NH, CN, C_3_ and C_2_ production rates of comet C/2012 F6(Lemmon) obtained using the TRAPPIST telescope (table4)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateDate of the observationstime.epochnullabler[-2/1.7] Heliocentric DistanceAUpos.distance;pos.heliocentricfloatQ(OH)? OH production rate (molecules/s)s**-1stat.fit.paramdoublenullablee_Q(OH)? rms uncertainty on Q(OH)s**-1stat.errordoublenullableQ(H2O)? H_2_O production rate (molecules/s)s**-1stat.fit.paramdoublenullablee_Q(H2O)? rms uncertainty on Q(H2O)s**-1stat.errordoublenullableQ(NH)? NH production rate (molecules/s)s**-1stat.fit.paramdoublenullablee_Q(NH)? rms uncertainty on Q(NH)s**-1stat.errordoublenullableQ(CN)? CN production rate (molecules/s)s**-1stat.fit.paramdoublenullablee_Q(CN)? rms uncertainty on Q(CN)s**-1stat.errordoublenullableQ(C3)? C_3_ production rate (molecules/s)s**-1stat.fit.paramdoublenullablee_Q(C3)? rms uncertainty on Q(C3)s**-1stat.errordoublenullableQ(C2)? C_2_ production rate (molecules/s)s**-1stat.fit.paramdoublenullablee_Q(C2)? rms uncertainty on Q(C2)s**-1stat.errordoublenullableJ/A+A/574/A38/afrhoA({alpha})f_{rho}_ values of comet C/2012 F6 (Lemmon) obtained using the TRAPPIST telescope (table6)r[-2/1.7] Heliocentric DistanceAUpos.distance;pos.heliocentricfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateDate of the observations (UT) (YYYY MMM DD)time.epochnullableUC? A({alpha})f_{rho}_ from UC filtercmstat.fit.paramdoublenullablee_UC? rms uncertainty on UCcmstat.errordoublenullableBC? A({alpha})f_{rho}_ from BC filtercmstat.fit.paramdoublenullablee_BC? rms uncertainty on BCcmstat.errordoublenullableGC? A({alpha})f_{rho}_ from GC filtercmstat.fit.paramdoublenullablee_GC? rms uncertainty on GCcmstat.errordoublenullableRC? A({alpha})f_{rho}_ from RC filtercmstat.fit.paramdoublenullablee_RC? rms uncertainty on RCcmstat.errordoublenullable