The secular light curves of comets presented in this web page, provide a significant
          amount of information on the photometric behaviour of these objects, and thus are a
          useful tool to plan the observation of specific comets.   Over 18 new parameters are
          measured from the plots, some of them very useful like the turn on point, Ron, Ton,
          and the turn off points, like Roff, Toff, which indicate the initiation and ending of
          activity and coma appearence.   Another useful parameter is P-AGE, the photometric
          age, which is an attempt to put an age on a comet.   We are currently working on
          about 42 comets, which are at differente stages of reduction.   To complete this work
          we had to write about 24 Fortran programs to reduced data, calculate orbits, print
          information in the proper format, calculate phase and elongation angles, fit envelopes,
          etc.  It took more than a year to have all these programs running without a glich.   We
          have also completed data gathering on many objects.  Our current bibliography on
          comets amounts now to more than a thousand papers.     Many of these plot  are
          currently being readied for publication.   If you need a secular light curve for
          planning pourposes, just write and request it.  It may be ready.  If you have observations,
          specially of the nucleus, please send a copy to be sure that they are included in the
          next version of the plots.  
                   The versions published here are usually Version 1.0, which means that they have
          not been yet published an thus they are preliminary.   They may change by the time
          they are sent for publication.  Version 5.0 means that the light curve has been published
          in 2005.  
                   Currently the secular light curve of 9P/Tempel 1 is already in its second revision,
          having been updated with current observations.   Thus do not use the old version.
          published in the paper in Icarus.
                   Your feedback is important.  We wellcome your suggestions, corrections,
          additions, observations, etc.  

          Ignacio Ferrín,
          Center for Fundamental Physics,
          University of the Andes,
          Mérida, VENEZUELA.