How to change Projected Coordinate System???

Question

Hi Everybody,

I have 15 Feauture Datasets in one Personal GDB. After collecting some data in ArcMap I recognize 7 Feauture Datasets coordinate system is in Pulkovo_1942_Gauss_Kruger_zone_8 but other 8 is in Pulkovo_1942_GK_Zone_9. How can I change all of my collecting data to Pulkovo_1942_Gauss_Kruger_zone_8. 
The raster data set and photo which I use for same data for editing in Pulkovo_1942_Gauss_Kruger_zone_8.

My second question is why the arcmap dont give me on screen error before I started to editing for different coordinate system.

After all when I am change Coordinate system in ArcCatalog and open my vector data in ArcMap some of data going to left side and some of data go to right side.

Please help me... Thanks

TengizMAMMADOV · Answer

Thank you for help.
I am trying some ways to re-project data and use them in same coordinate system.
After all in first I set the coordinate system to the GCS-WGS-84.
Than in second set projected coordinate system again but using 
**ArcToolbox-Data Management Tool-Projection-Feature projection.
I don't know any idea about this way re-project. Is it done? 
But now everything is ok.
Thank you.
Have a nice day.

AsrujitSengupta · Answer

Hi,

You can change the projection of the datasets  using the " Define Projections " tool.

Irregularities may occur, as you were using a different projection system while editing the features earlier.

Regards,
Asrujit

PeterYurkosky1 · Answer

My second question is why the arcmap dont give me on screen error before I started to editing for different coordinate system.

After all when I am change Coordinate system in ArcCatalog and open my vector data in ArcMap some of data going to left side and  some of data go to right side.

How did you change the coordinate system in ArcCatalog? Did you open the datasets' property page, and change it in the "Coordinate System" tab? That only changes the declared coordinate system; it doesn't change the actual x,y values in the dataset. If your datasets are actually in zone 9, they need to be reprojected (using the Project geoprocessing tool) to zone 8. Have you tried this?