I have a topo map which I want to georeference into Deir ez Zor / Levant Stereographic (EPSG:22780) and then transform into WGS 84/UTM zone 36N (EPSG:32636).
My goal is have as little divergence to the BING satellite imagery provided by the QuickmapServices QGIS plugin as possible. The map depicts an area in Lebanon.
So, I use the coordinates which are specified through the topo maps grid, to georeference the map, E.g. x: 355700 y: 72800. From the additional information given by the author. The given information is sparse, as the author did not give any type of identifyier but called the crs he used only the "syrian system" of which there are several in Lebanon accorsing to epsg.io.
After some trying-out, I concluded that he most likely used Deir ez Zor / Levant Stereographic. I also found out that the coordinates are in fact negative: x: -355700 y: -72800.
After georef. the map appears significantly off of the underlying satellite imagery (some 20 - 30 m). However, I thought this might fix itself by reprojecting the map into UTM 36N. But no matter what parameters I choose for reprojection, the transformed map is identical to the originally referenced one, and thus still off of the satellite imagery. The project CRS was also set to UTM 36N.
I have some gps data in WGS84 / UTM 36N from the same area, which aligns perfectly with the satellite imagery. So, I don't think the problem is caused by the inaccuracy of the projected satellite image.