All - Steve Walter pointed out an obvious thing to try - Excel can format columns as Day/Time; I had used that several years ago but had forgotten about it. In my defense, I checked with two people who are considered "power users" of Excel here and neither mentioned that. Still, if anyone had a good Unix (should have mentioned that I use Macs) application, let me know. I looked at GNUPlot a while ago and it seemed to be complex. I run several Unix applications - Gpredict, Exiftool, etc etc and feel comfortable with them. Charles Phillips Spaceflight Research, LLC Houston, Texas 713-882-4578 sites.google.com/site/spaceflightresearchprojects/ > On July 22, 2019 at 7:30 PM Charles Phillips <charles_at_spaceflightresearch.net> wrote: > > Colleagues - > > This group seems to have a number of people with a wide variety of talents, can I post a question that many people must have solved? > > I am plotting various parameters vs time, angles like the inclination and Right Ascension of the Ascending Node - so the angles vary from 0 to 360. I am plotting with Excel for now so, if the angle is on the vertical axis Excel does a good job. > > But I am using epoch time on the horizontal axis - plotting RAAN vs day most of the time. As long as I use only a single year this works - but Excel assumes that between day 001 of 2014 and day 001 of 2015 there are 1000 "days". If I plot only one year I just ignore everything past day 365 - doesn't look elegant. > > If I swap horizontal and vertical axes of course the problem just changes a bit. > > I see graphs/plots in various publications where the authors plot occurrences per day and the horizontal axis resets to zero after 365 - but what software did they use? > > I have looked around for various data analysis packages but they are another learning curve that I'd rather avoid. There must be usable packages that perhaps someone would recommend? > > Of course one of my steps has been to ask The Great Wizard Of The Harvard-Smithsonian Center for Astrophysics, Jonathan McDowell. He recommended that I just "rebaseline" epoch time to map the epochs so they would span 1000 steps - is that clear? That is pretty easy to do, I could add a few lines to my C++ code. So the year would be transformed into a multiple of 1000 "days". > > But maybe I could find a better (yet relatively simple) application that I could set the horizontal axis to run 0 - 360 and reset to zero? This problem has certainly been solved a long time ago. People in this group must need to do this. > > Is there a forum out there somewhere that could help me? > > Thanks. > > > Charles Phillips > Spaceflight Research, LLC > Houston, Texas > 713-882-4578 > sites.google.com/site/spaceflightresearchprojects/ > _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Mon Jul 22 2019 - 23:26:30 UTC
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