J/AJ/152/102ivo://CDS.VizieR/J/AJ/152/102doi:10.26093/cds/vizier.51520102CDSBrown P.J.Breeveld A.Roming P.W.A.Siegel M.2017-02-06T14:53:15Z2016-12-05T12:39:57ZCDS support team

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

cds-question@unistra.frsupernovaespectroscopyultraviolet-astronomyWe discuss the transformation of observed photometry into flux for the creation of spectral energy distributions (SED) and the computation of bolometric luminosities. We do this in the context of supernova studies, particularly as observed with the Swift spacecraft, but the concepts and techniques should be applicable to many other types of sources and wavelength regimes. Traditional methods of converting observed magnitudes to flux densities are not very accurate when applied to UV photometry. Common methods for extinction and the integration of pseudo-bolometric fluxes can also lead to inaccurate results. The sources of inaccuracy, though, also apply to other wavelengths. Because of the complicated nature of translating broadband photometry into monochromatic flux densities, comparison between observed photometry and a spectroscopic model is best done by forward modeling the spectrum into the count rates or magnitudes of the observations. We recommend that integrated flux measurements be made using a spectrum or SED which is consistent with the multi-band photometry rather than converting individual photometric measurements to flux densities, linearly interpolating between the points, and integrating. We also highlight some specific areas where the UV flux can be mischaracterized.2016AJ....152..102Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/152/102CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/ApJ/805/74 : SN2014J Swift/UVOT light curves (Brown+, 2015)J/ApJS/212/18 : An atlas of UV-to-MIR galaxy SEDs (Brown+, 2014)J/ApJ/721/1608 : Absolute UV magnitudes of type Ia SNe (Brown+, 2010)J/PASP/110/863 : A Stellar Spectral Flux Library: 1150 - 25000 A (Pickles 1998)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/152/102https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/152/102http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/152/102https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/152/102https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/152/102http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/152/102GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapUVdefaultJ/AJ/152/102/table1Flux conversion factorsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSpectrumInput spectrumsrc.spTypecharRefSpectrum Reference (1)meta.ref;pos.frameintuvw2Swift Ultraviolet/Optical Telescope (UVOT) uvw2 filter conversion factor (2)aJ.m**-2.nm**-1.count**-1stat.valuedoubleuvm2Swift/UVOT uvm2 filter conversion factor (2)aJ.m**-2.nm**-1.count**-1stat.valuedoubleuvw1Swift/UVOT uvw1 filter conversion factor (2)aJ.m**-2.nm**-1.count**-1stat.valuedoubleuSwift/UVOT u filter conversion factor (2)aJ.m**-2.nm**-1.count**-1stat.valuedoublebSwift/UVOT b filter conversion factor (2)aJ.m**-2.nm**-1.count**-1stat.valuedoublevSwift/UVOT v filter conversion factor (2)aJ.m**-2.nm**-1.count**-1stat.valuedouble