<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0185-1101</journal-id>
<journal-title><![CDATA[Revista mexicana de astronomía y astrofísica]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. mex. astron. astrofis]]></abbrev-journal-title>
<issn>0185-1101</issn>
<publisher>
<publisher-name><![CDATA[Universidad Nacional Autónoma de México, Instituto de Astronomía]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0185-11012017000100059</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Long-term optical activity of the hard X-Ray flaring star DG CVN]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[&#352;imon]]></surname>
<given-names><![CDATA[Vojt&#283;ch]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Czech Academy of Sciences Astronomical Institute ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Czech Republic</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>00</month>
<year>2017</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>00</month>
<year>2017</year>
</pub-date>
<volume>53</volume>
<numero>1</numero>
<fpage>59</fpage>
<lpage>66</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0185-11012017000100059&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0185-11012017000100059&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0185-11012017000100059&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract DG CVn is a young late-type star which displayed an X-ray and optical superflare in 2014. This paper presents an analysis of the long-term activity of this object in the optical band. I used the photographic data from DASCH (Digital Access to a Sky Century @ Harvard). These measurements from the years 1895-1989 cover the blue spectral region. CCD V -band ASAS data were used for several UV Cettype stars to place the activity of DG CVn in the context of flaring stars. I show that three large brightenings (flares) of DG CVn by more than 1 mag were detected on the DASCH plates. The character of the long-term activity (regarding the histogram of brightness) of DG CVn is compatible with those of flaring stars UV Cet and V371 Ori. The flares brighter than &#8764; 0.4 mag represent less than 1 percent of the observed data in all three objects.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen DG CVn es una estrella joven y tardía, que en 2014 presentó una super ráfaga en la banda óptica y en rayos X. En este trabajo analizamos la actividad de este objeto en la banda óptica durante un largo intervalo de tiempo, usando los datos fotográficos de DASCH (Digital Access to a Sky Century @ Harvard). Estas medidas abarcan desde 1895 hasta 1989 en la región espectral azul. Se usaron datos de varias estrellas tipo UV Cet tomados de ASAS en la banda V del CCD para situar la actividad de DG CVn en el contexto de las estrellas ráfaga. Se muestra que las tres grandes ráfagas de DG CVn (que aumentaron su luminosidad por más de 1 magnitud) están presentes en las placas DASCH. Según el histograma de las magnitudes, la naturaleza de la actividad a largo plazo de DG CVn es compatible con la de las estrellas ráfaga UV Cet y V371 Ori. Las ráfagas de m &#769;as de 0.4 mag representan menos del 1% de los datos observados para las tres estrellas.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[methods: observational]]></kwd>
<kwd lng="en"><![CDATA[radiation mechanisms: general]]></kwd>
<kwd lng="en"><![CDATA[stars: flare]]></kwd>
<kwd lng="en"><![CDATA[stars: individual (DG CVn)]]></kwd>
<kwd lng="en"><![CDATA[stars: late-type]]></kwd>
<kwd lng="en"><![CDATA[X-rays: stars]]></kwd>
</kwd-group>
</article-meta>
</front><back>
<ref-list>
<ref id="B1">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Bade]]></surname>
<given-names><![CDATA[N.]]></given-names>
</name>
<name>
<surname><![CDATA[Engels]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Voges]]></surname>
<given-names><![CDATA[W.]]></given-names>
</name>
</person-group>
<source><![CDATA[A&amp;AS]]></source>
<year>1998</year>
<volume>127</volume>
<page-range>145</page-range></nlm-citation>
</ref>
<ref id="B2">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Beers]]></surname>
<given-names><![CDATA[T. C.]]></given-names>
</name>
<name>
<surname><![CDATA[Bestman]]></surname>
<given-names><![CDATA[W.]]></given-names>
</name>
<name>
<surname><![CDATA[Wilhel Melikian]]></surname>
<given-names><![CDATA[R]]></given-names>
</name>
</person-group>
<source><![CDATA[AJ]]></source>
<year>1994</year>
<volume>108</volume>
<page-range>268</page-range></nlm-citation>
</ref>
<ref id="B3">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Beuzit]]></surname>
<given-names><![CDATA[J.-L.]]></given-names>
</name>
<name>
<surname><![CDATA[Ségransan]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Forveille]]></surname>
<given-names><![CDATA[T.]]></given-names>
</name>
</person-group>
<source><![CDATA[A&amp;A]]></source>
<year>2004</year>
<volume>425</volume>
<page-range>997</page-range></nlm-citation>
</ref>
<ref id="B4">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Buccino]]></surname>
<given-names><![CDATA[A. P]]></given-names>
</name>
<name>
<surname><![CDATA[Díaz]]></surname>
<given-names><![CDATA[R. F]]></given-names>
</name>
<name>
<surname><![CDATA[Luoni]]></surname>
<given-names><![CDATA[M. L]]></given-names>
</name>
<name>
<surname><![CDATA[Abrevaya]]></surname>
<given-names><![CDATA[X. C]]></given-names>
</name>
<name>
<surname><![CDATA[Mauas]]></surname>
<given-names><![CDATA[P. J. D]]></given-names>
</name>
</person-group>
<source><![CDATA[AJ]]></source>
<year>2011</year>
<volume>141</volume>
<page-range>34</page-range></nlm-citation>
</ref>
<ref id="B5">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Caballero-García]]></surname>
<given-names><![CDATA[M. D.]]></given-names>
</name>
<name>
<surname><![CDATA[&#352;imon]]></surname>
<given-names><![CDATA[V.]]></given-names>
</name>
<name>
<surname><![CDATA[Jelínek]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
</person-group>
<source><![CDATA[MNRAS]]></source>
<year>2015</year>
<volume>452</volume>
<page-range>4195</page-range></nlm-citation>
</ref>
<ref id="B6">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Delfosse]]></surname>
<given-names><![CDATA[X.]]></given-names>
</name>
<name>
<surname><![CDATA[Forveille]]></surname>
<given-names><![CDATA[T.]]></given-names>
</name>
<name>
<surname><![CDATA[Perrier]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
</person-group>
<source><![CDATA[A&amp;A]]></source>
<year>1998</year>
<volume>331</volume>
<page-range>581</page-range></nlm-citation>
</ref>
<ref id="B7">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[D&#8217;Elia]]></surname>
<given-names><![CDATA[V.]]></given-names>
</name>
<name>
<surname><![CDATA[Gehrels]]></surname>
<given-names><![CDATA[N.]]></given-names>
</name>
<name>
<surname><![CDATA[Holland]]></surname>
<given-names><![CDATA[S. T.]]></given-names>
</name>
</person-group>
<source><![CDATA[GCN]]></source>
<year>2014</year>
<volume>16158</volume>
<numero>1</numero>
<issue>1</issue>
</nlm-citation>
</ref>
<ref id="B8">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Donati]]></surname>
<given-names><![CDATA[J.-F.]]></given-names>
</name>
<name>
<surname><![CDATA[Landstreet]]></surname>
<given-names><![CDATA[J. D]]></given-names>
</name>
</person-group>
<source><![CDATA[ARA&amp;A]]></source>
<year>2009</year>
<volume>47</volume>
<page-range>333</page-range></nlm-citation>
</ref>
<ref id="B9">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Drake]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<name>
<surname><![CDATA[Osten]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<name>
<surname><![CDATA[Page]]></surname>
<given-names><![CDATA[K. L.]]></given-names>
</name>
</person-group>
<source><![CDATA[ATel]]></source>
<year>2014</year>
<volume>6121</volume>
<page-range>1</page-range></nlm-citation>
</ref>
<ref id="B10">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Drake]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<name>
<surname><![CDATA[Osten]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<name>
<surname><![CDATA[Page]]></surname>
<given-names><![CDATA[K. L.]]></given-names>
</name>
</person-group>
<source><![CDATA[HEAD]]></source>
<year>2014</year>
<volume>1440406</volume>
</nlm-citation>
</ref>
<ref id="B11">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Fender]]></surname>
<given-names><![CDATA[R. P.]]></given-names>
</name>
<name>
<surname><![CDATA[Anderson]]></surname>
<given-names><![CDATA[G. E.]]></given-names>
</name>
<name>
<surname><![CDATA[Osten]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
</person-group>
<source><![CDATA[MNRAS]]></source>
<year>2015</year>
<volume>446</volume>
<page-range>L66</page-range></nlm-citation>
</ref>
<ref id="B12">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Geyer]]></surname>
<given-names><![CDATA[D. W.]]></given-names>
</name>
<name>
<surname><![CDATA[Harrington]]></surname>
<given-names><![CDATA[R. S.]]></given-names>
</name>
<name>
<surname><![CDATA[Worley]]></surname>
<given-names><![CDATA[Ch. E]]></given-names>
</name>
</person-group>
<source><![CDATA[AJ]]></source>
<year>1988</year>
<volume>95</volume>
<page-range>1841</page-range></nlm-citation>
</ref>
<ref id="B13">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Grindlay]]></surname>
<given-names><![CDATA[J]]></given-names>
</name>
<name>
<surname><![CDATA[Tang]]></surname>
<given-names><![CDATA[S]]></given-names>
</name>
<name>
<surname><![CDATA[Los]]></surname>
<given-names><![CDATA[E]]></given-names>
</name>
<name>
<surname><![CDATA[Servillat]]></surname>
<given-names><![CDATA[M]]></given-names>
</name>
<name>
<surname><![CDATA[Griffin]]></surname>
<given-names><![CDATA[E]]></given-names>
</name>
<name>
<surname><![CDATA[Hanisch]]></surname>
<given-names><![CDATA[R]]></given-names>
</name>
<name>
<surname><![CDATA[Seaman]]></surname>
<given-names><![CDATA[R]]></given-names>
</name>
</person-group>
<source><![CDATA[IAUS 285, New Horizons in Time-Domain Astronomy]]></source>
<year>2012</year>
<numero>29</numero>
<issue>29</issue>
<publisher-loc><![CDATA[Cambridge, MA ]]></publisher-loc>
<publisher-name><![CDATA[CUP]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B14">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Henry]]></surname>
<given-names><![CDATA[T. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Kirkpatrick]]></surname>
<given-names><![CDATA[J. D.]]></given-names>
</name>
<name>
<surname><![CDATA[Simons]]></surname>
<given-names><![CDATA[D. A]]></given-names>
</name>
</person-group>
<source><![CDATA[AJ]]></source>
<year>1994</year>
<volume>108</volume>
<page-range>1437</page-range></nlm-citation>
</ref>
<ref id="B15">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Hosey]]></surname>
<given-names><![CDATA[A. D]]></given-names>
</name>
<name>
<surname><![CDATA[Henry]]></surname>
<given-names><![CDATA[T. J]]></given-names>
</name>
<name>
<surname><![CDATA[Jao]]></surname>
<given-names><![CDATA[W.-Ch]]></given-names>
</name>
</person-group>
<source><![CDATA[AJ]]></source>
<year>2015</year>
<volume>150</volume>
<page-range>6</page-range></nlm-citation>
</ref>
<ref id="B16">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Hünsch]]></surname>
<given-names><![CDATA[M]]></given-names>
</name>
<name>
<surname><![CDATA[Schmitt]]></surname>
<given-names><![CDATA[J. H. M. M]]></given-names>
</name>
<name>
<surname><![CDATA[Sterzik]]></surname>
<given-names><![CDATA[M. F]]></given-names>
</name>
</person-group>
<source><![CDATA[A&amp;AS]]></source>
<year>1999</year>
<volume>135</volume>
<page-range>319</page-range></nlm-citation>
</ref>
<ref id="B17">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Ishida]]></surname>
<given-names><![CDATA[K.]]></given-names>
</name>
<name>
<surname><![CDATA[Ichimura]]></surname>
<given-names><![CDATA[K.]]></given-names>
</name>
<name>
<surname><![CDATA[Shimizu]]></surname>
<given-names><![CDATA[Y.]]></given-names>
</name>
</person-group>
<source><![CDATA[Ap&amp;SS]]></source>
<year>1991</year>
<volume>182</volume>
<page-range>227</page-range></nlm-citation>
</ref>
<ref id="B18">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Kafka]]></surname>
<given-names><![CDATA[S]]></given-names>
</name>
</person-group>
<source><![CDATA[OLEB]]></source>
<year>2012</year>
<volume>42</volume>
<page-range>143</page-range></nlm-citation>
</ref>
<ref id="B19">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Lund]]></surname>
<given-names><![CDATA[M. B.]]></given-names>
</name>
<name>
<surname><![CDATA[Pepper]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Stassun]]></surname>
<given-names><![CDATA[K. G.]]></given-names>
</name>
</person-group>
<source><![CDATA[arXiv]]></source>
<year>2016</year>
</nlm-citation>
</ref>
<ref id="B20">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Luyten]]></surname>
<given-names><![CDATA[W. J]]></given-names>
</name>
</person-group>
<source><![CDATA[ApJ]]></source>
<year>1949</year>
<volume>109</volume>
<page-range>532</page-range></nlm-citation>
</ref>
<ref id="B21">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Luyten]]></surname>
<given-names><![CDATA[W. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Hoffleit]]></surname>
<given-names><![CDATA[D]]></given-names>
</name>
</person-group>
<source><![CDATA[AJ]]></source>
<year>1954</year>
<volume>59</volume>
<page-range>136</page-range></nlm-citation>
</ref>
<ref id="B22">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Mavridis]]></surname>
<given-names><![CDATA[L. N.]]></given-names>
</name>
<name>
<surname><![CDATA[Avgoloupis]]></surname>
<given-names><![CDATA[S]]></given-names>
</name>
</person-group>
<source><![CDATA[A&amp;A]]></source>
<year>1986</year>
<volume>154</volume>
<page-range>171</page-range></nlm-citation>
</ref>
<ref id="B23">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Melikian]]></surname>
<given-names><![CDATA[N. D.]]></given-names>
</name>
<name>
<surname><![CDATA[Tamazian]]></surname>
<given-names><![CDATA[V. S.]]></given-names>
</name>
<name>
<surname><![CDATA[Samsonyan]]></surname>
<given-names><![CDATA[A. L.]]></given-names>
</name>
</person-group>
<source><![CDATA[Ap]]></source>
<year>2011</year>
<volume>54</volume>
<page-range>469</page-range></nlm-citation>
</ref>
<ref id="B24">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Pazzani]]></surname>
<given-names><![CDATA[V.]]></given-names>
</name>
<name>
<surname><![CDATA[Rodono]]></surname>
<given-names><![CDATA[M]]></given-names>
</name>
</person-group>
<source><![CDATA[Ap&amp;SS]]></source>
<year>1981</year>
<volume>77</volume>
<page-range>347</page-range></nlm-citation>
</ref>
<ref id="B25">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Pojmanski]]></surname>
<given-names><![CDATA[G]]></given-names>
</name>
</person-group>
<source><![CDATA[AcA]]></source>
<year>1997</year>
<volume>47</volume>
<page-range>467</page-range></nlm-citation>
</ref>
<ref id="B26">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Riedel]]></surname>
<given-names><![CDATA[A. R]]></given-names>
</name>
<name>
<surname><![CDATA[Finch]]></surname>
<given-names><![CDATA[Ch. T]]></given-names>
</name>
<name>
<surname><![CDATA[Henry]]></surname>
<given-names><![CDATA[T. J]]></given-names>
</name>
</person-group>
<source><![CDATA[AJ]]></source>
<year>2014</year>
<volume>147</volume>
<page-range>85</page-range></nlm-citation>
</ref>
<ref id="B27">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Robb]]></surname>
<given-names><![CDATA[R. M.]]></given-names>
</name>
<name>
<surname><![CDATA[Balam]]></surname>
<given-names><![CDATA[D. D.]]></given-names>
</name>
<name>
<surname><![CDATA[Greimel]]></surname>
<given-names><![CDATA[R]]></given-names>
</name>
</person-group>
<source><![CDATA[IBVS]]></source>
<year>1999</year>
<volume>4714</volume>
<page-range>1</page-range></nlm-citation>
</ref>
<ref id="B28">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Vida]]></surname>
<given-names><![CDATA[K.]]></given-names>
</name>
<name>
<surname><![CDATA[Kriskovics]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Oláh]]></surname>
<given-names><![CDATA[K]]></given-names>
</name>
</person-group>
<source><![CDATA[AN]]></source>
<year>2013</year>
<volume>334</volume>
<page-range>972</page-range></nlm-citation>
</ref>
<ref id="B29">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Xu]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Bai]]></surname>
<given-names><![CDATA[C.-H.]]></given-names>
</name>
<name>
<surname><![CDATA[Zhang]]></surname>
<given-names><![CDATA[X.]]></given-names>
</name>
</person-group>
<source><![CDATA[GCN]]></source>
<year>2014</year>
<volume>16159</volume>
<page-range>1</page-range></nlm-citation>
</ref>
</ref-list>
</back>
</article>
