I think you aren’t looking at an ion tail not the orbital tail. Guide only shows the latter. One is affected by solar winds and magnetic line. Depending on the observer view, one tail can be more prominent than the other. Unfortunately guide or other softwares will only show the orbital. 

Hello all,

 

when I hunted about older comet images and diagnosed the comets position, I experienced a never before seen incorrect display of the comet in Guide9.

I noticed that in case of comet Johnson (C/2015 V2 - 2017-05-17 22:34:48 UTC) Guide9 displayed the comets position with some offset and - and this was what startled me - the tail showing in a total wrong direction in comparison to my images.

Comparatively I find the display of comet 21P/Giacobini-Zinner (2018-08-16 21:15:24) in total accordance with my images.

 

To clarify what I found I uploaded some graphics here.

 

Have others experienced such unexpected behavior of Guide9 too? And is there a clearing explanation of this riddle?

 

Thanks for noticing,

Rolf Stadelmaier