Comment 1 for bug 1380242

Hell fbilki,
You say that DeltaT has nothing to do with the rotation of the earth. That is not true. DeltaT is the accumulative difference between the rotation of the earth (close to 24 hours, not not fully) and a 'day' of precisely 24*60*60 SI seconds. see also https://en.wikipedia.org/wiki/%CE%94T Any modern ephemeris uses a 24*60*6o SI seconds per day, and thus one needs to adjust the time to map real time.
But I don't think your point is only that, so let me know, perhaps I can help.
All the best,

Victor