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I was wondering if anyone would be able to tell me the difference between UTM UPS GDA94 (set on my GPS) and GDA94/MGA zone 56, the nearest equivalent I can find in ArcGIS (under Projected Coordinate Systems - National Grid - Australia).

When I import GPS coordinates (UTM UPS GDA94) into ArcGIS in an excel file and onto a GCS GDA94 dataframe, I set the projection to GDA94/MGA zone 56, and they appear in the correct place on the map.

I'm still coming to terms with different coordinate systems.

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You may not receive definitive answers without details of your GPS system settings, but in essence they should be the same.

It is still difficult to find clear definition of MGA (Map Grid of Australia 1994), even in the website of Geoscience Australia. It goes back to older Australian Map Grid (AMG) system. Both AMG and MGA use UTM-based concept, with same projection parameters, but from the different ellipsoids.

To avoid confusion, state and federal governments decided to change those names; AGD should be replaced by GDA, and AMG by MGA.

Bottomline: please check your GPS settings. If it is UTM zone 56S based on GDA94 (ITRF92:GRS80), you would be good with GDA94/MGA zone56.

  • Thank you Kazuhito. I have checked my GPS settings and they are: – NicoleG Mar 26 '17 at 2:51
  • UTM UPS, GDA 94, GRS 80. There is no mention of UTM zone 56S, but the settings I have chosen are the only appropriate ones available from the list. Does that sound right? – NicoleG Mar 26 '17 at 2:58
  • That does sound right. If you were in other UTM zone, your GPS reading would have put you far off your desired location when plotted on the ArcGIS. – Kazuhito Mar 26 '17 at 3:34

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