You can account for both the datum shift and crustal motion (i.e., how much a point moved due to plate tectonics between 19) using the NGS HTDP tool. The standard reference epoch associated with WGS84(TRANSIT) and NAD83(1986) is 1984.0, but you would have to research the epoch date associated with your existing GIS datasets to be really accurate. For example, the ITRF00 coordinate from your PFO differential correction probably has an associated epoch date of 1997.0. If your accuracy needs are <2-3 meters you should consider not only accounting for the datum shift (i.e., the position difference between ITRF00 and NAD83(1986)), but also accounting for position shifts due to crustal motion between the epoch dates associated with the 2 coordinates. Export the NAD83(2011) coordinates, then use the NGS NCAT tool to convert to NAD83(1986). In the same vein, in ArcMap you can convert from ITRF00->ITRF05->ITRF08, then from ITRF08 to NAD83(2011). The NCAT tool is used to convert between various NAD83 adjustments, but NAD83(CORS) is not one of the options. In my locale the differences between these NAD83 realizations are typically 4 to 12 cm, but can be up to. Note that the ITRF00 to NAD83(HARN) or (2011) transform is actually the published transformation parameters for ITRF00 to NAD83(CORS96) at epoch 1997.0, so assuming NAD83(CORS96) = NAD83(HARN) or (2011) will introduce some error. Export the NAD83(HARN) or (2011) coordinates, then use the NGS NCAT tool to convert coordinates to NAD83(1986). In ArcMap you can project from ITRF00 to NAD83(HARN) or from ITRF00 to NAD83(2011). I don’t know what the errors associated with these 2 transforms are in your area, but my understanding is that transformations involving NAD83(1986) are problematic and may have distortions >1m (see here). Keep in mind however, that there is also error inherent in the various transformations methods that may make transforming not worthwhile. To sum, ArcGIS does not have an ITRF00->NAD83(1986) transformation available, so you cannot project your GPS data “on the fly” or using the “Project” tool … unless you create the needed 2 nd ITRF90->WGS84(TRANSIT) transform. After transforming you can then “Project Define” the WGS84(TRANSIT) output to NAD83. After you create the custom transformation and open the ‘Project’ tool, ArcGIS should automatically offer a composite transformation using its existing ITRF00->ITRF90 + your custom ITRF90->WGS84(TRANSIT) transformations when you go to select the ‘Geographic Transformation’ method. However, you can create a custom transform in ArcGIS (the parameters are available here) using the “Create Custom Geographic Transformation” tool.
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In ArcGIS Desktop 10.7 and ArcGIS Pro 2.4 (not sure about other versions) there is an ITRF00->ITRF90 transformation, but there is not an ITRF90-to-WGS84(TRANSIT) transform. As you mentioned, WGS84(original) - also known as WGS84(TRANSIT) - is essentially equivalent to NAD83(1986). You can get from ITRF00 to NAD83(1986) by stepping through 2 transformations: 1) ITRF00->ITRF90, then 2) ITRF90->WGS84(original). On the other hand, if your project requires high accuracy coordinates you may want to consider applying datum transformations. If it is within your error budget, then try this scenario. You can check for NGS bench mark datasheets in your project area that list coordinates for multiple NAD83 adjustments to see what these differences are in your area.
Or, project from ITRF00 to NAD83(CORS96) and just assume that NAD83(CORS96) = NAD83(1986). Also, consider the accuracy of your existing NAD83(1986) GIS map data. In this case, just assume ITRF00 = NAD83(1986). If 2 m falls within your error budget, then there is likely no need to transform. To answer your question, deciding whether to transform your GPS data from ITRF00 to NAD83(1986) all depends on the accuracy requirements of your project. ITRF00 (which is equivalent to WGS84(G1150) at the decimeter level), differs from NAD83(1986) by ~1 to 2+ meters horizontally, depending on your location.
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