A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Antoine Couëtte
Date: 2016 Jun 21, 00:08 -0700
Yes ! Your results and graphs for distance and relative velocity seem all correct. Their trends are adequately shown : definitely in this example you cannot approximate neither the distances nor the relative velocities in a linear fashion.
When I have more time, i.e. in one week from now, I am planning to do a similar plotting of the distances with Frank's OLC (On Line Lunar Computer).
I will probably work my Plotting graph from a slightly more southern point (maybe as south as Dakar in Senegal ?) from where the minimum distance will be just above 0'0 (close to a grazing occultation). I will find this spot by trial and error. The non-linear curve appearance should be even more visible.
While your graphs for N30W010 seem to include all visible effects as I earlier said, for my intended computation next week I am sure that Frank's OLC results will include all visible effects.
NOTE : The non linear appearance of the distance curve is sometimes even more visible when you compute it for the Sun Limb - Moon Distances as seen from a spot just outside the path of a Solar Eclipse. Such event is not visible at all at the naked eye, because the Sun is not occulted at all by any part of the invisible Moon as seen from such spots, but I think that Frank's OLC should give good results for such cases also. As a practical exercise, you could try to plot the SUN Limb to Moon Limb Distances on 03 October 1986 during the local day-time from N10°-W090° for the Solar Eclipse which occurred on that day. The N10°-W090° position is just outside the southern limit of this eclipse (REF : The Astronomical Almanac for 1986, Page A82).
Last but not least, if meanwhile - i.e. before next week - someone can perform the 2 "Moon Limb - Other Body [Limb]" Topographic distances Plotting exercises I just mentioned here-above (i.e. the Mars Lunar on 30 Jul 2000 seen from a spot more south than N30-W010 to be determined by trial and error (maybe Dakar in Senegal ?) and the Solar "near miss" Eclipse as seen from N10°W090° on 03 Oct 1986), that will be great, and will save me some time.