Converting Adindan UTM (Ethiopia)

[LanceStewart]

Total n00b here. I am having some issues accurately projecting a set of coordinates in WGS 1984. Despite my best efforts the points appear to be 150-200m off (estimate). Maybe someone can guide me towards a resource or solution?

I was given a set of coordinates similar to this example:

Adindan 37P 68888 E 1292222 N

I need to convert to decimal degrees to project in WGS 1984.

[DanPatterson_Retired]

what is the datum of the coordinates?  looks like a datum shift if they are all relatively the same.  You will need more than just the zone, easting and northing to resolve it since you may need to specify the geographic transformation

[LanceStewart]

Thanks for your response Dan. The spread sheet lists "Adindan" as the Datum.

[DanPatterson_Retired]

Adindan

http://www.ijmse.org/Volume4/Issue5/paper10.pdf

plus loads more... just Dr Googled Adindan, which suggests that it is a datum shift, whether there is a geographic transformation for it, you will have to look in the Project tool in the transformation section to see if any are suggested, otherwise, readup on the spheriod used in it as compared to the WGS84 datum.

[LanceStewart]

Thanks Dan for your suggestions and guidance!

[NeilAyres]

Here's the info from ASPRS Clifford Mugnier.

Which suggests that Adindan is a bit of a misnomer and it is real the Blue Nile datum.

But there are transforms available in the system.

See

Adindan_To_WGS_1984_4 WKID=1103 Accuracy=6.000

Page 2 and 44 of the geographic_transformations.pdf in the ArcGIS documentation folder.

[LanceStewart]

Thank you for the information Neil!

Between Dan and yourself I now understand the "how" and the "why".