Coordinate transformation from WGS 1984 to Everest 1830 or vice versa?

[SarveshDhakal]

I have been trying hard to find out how to convert the coordinate from Everest 1830 to WGS 1984? What I have been doing recently is insert two different data frames and specify two coordinate systems (datums). Add the layer/shapefile/feature with known coordinate system having proper datum. After that I drag the layer to another data frame and click on close when asked for Transformation. After that I right click the layer goto data and export and then export the feature/layer to the new coordinate system. It seems to work well. But however, there seem to be some error. I am not sure if its the right way of transforming the coordinate. I never use the Transformations when  I drag the feature to new data frame with different coordinate system. I want to be sure if it is the right way. I need expert help on this,

[DavidWilliams]

You should always specify a transformation

see: http://mappingcenter.esri.com/index.cfm?fa=ask.answers&q=1699

[MelitaKennedy]

We don't have any transformations for Everest 1830 because it's a ellipsoid (spheroid) and not a true geodetic datum/coordinate system. The data may be using Kalianpur 1937. Take a look at the geographic_transformations.pdf file located in your ArcGIS installation's Documentation folder for GCS that are used in India (or wherever the data is) and try some of them. It will mean redefining the Everest 1830 data with the Define Projection tool or the data's property page in ArcCatalog.

Melita