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I believe it comes down to they are on different spacecraft platforms. The Aqua data stream includes the near-real-time (NRT) ATT/EPH data that can be used to process data. Then later the refined ATT/EPH data are delivered, and any future refined L2 processing we do uses the refined ATT/EPH. Terra also has ATT/EPH data embedded in the data stream, and up to several years ago, those could be used to process the data NRT. The geo-location software no longer supports using that data. I don't know the details of why. It might be that the accuracy of the onboard data had become bad enough to use without some post processing.