Joe, I suppose for those who want to use a narrow (e.g. 30 minutes or less) grayline duration to try to catch a true grayline opening (when the entire path is aligned along the sunrise/sunset terminator), then it should probably be D-region sunset. In my case, at 40deg N, I am using 120 minute duration so it’s not going to make much difference.
BTW, I haven’t checked to see if the program does something sane when there is no sunrise or no sunset. Steve > On Jun 6, 2015, at 8:54 AM, Joe Taylor <j...@princeton.edu> wrote: > > Hi Bill, Steve, and all, > >> Remove redundant Fortran function >> >> lib/hopping.f90 has been superceded by C/C++ code except for the call >> to grayline() which is now called directly. >> http://sourceforge.net/p/wsjt/wsjt/5545/ > > Thanks for all the recent good additions to WSPR-mode functionality. > I've been temporarily buried in thinking about EME Echo mode... > > The commit comment about my grayline() routine reminded me that I wanted > to seek input on how our grayline range should be defined. > > As a placeholder, in the present routine grayline.f90 I defined the > grayline to be centered at the time when the sun is 50 arc minutes > (0.8333 deg) below the local horizon. This is normally taken to be the > time of sunrise or sunset. Of course, for ionospheric propagation > purposes what matters is whether the sun illuminates a specific layer of > the ionosphere. The end of D-layer illumination occurs when the sun is > something like 6.6 deg below the horizon. (The end of F-layer > illumination more like 14.2 deg below the horizon, but I think it's > D-layer absorption that we're most concerned eith here.) > > So... would it be better to center our grayline periods at the times > when the sun is about 6 degrees below the horizon -- also the end time > of what's normally taken to be "civil twilight" ? > > -- Joe, K1JT > > ------------------------------------------------------------------------------ > _______________________________________________ > wsjt-devel mailing list > wsjt-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/wsjt-devel ------------------------------------------------------------------------------ _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
