The parsing continues:
arxiv.org: 2507.21967
Jul 29 Feinstein, A. D. Noonan, J. W. Seligman, D. Z. Precovery Observations of 3I/ATLAS from TESS Suggest Possible Distant Activity
The TESS program, with word out on ATLAS, then went through their “old” data. It just so happens that TESS was pointed at the same region of sky where the interstellar object was. Images from May 7 (!) to early June (when the flying, staring observatory pointed to a different place) show the comet. Pushing out this far, we can hone our orbit solution for the body. Additionally, the fact that TESS could detect ATLAS (despite a small aperture) means that 3I looked pretty much the same as it does now- rather brighter than average, as comets go. This implies ATLAS was already active on May 7 (well, active for ATLAS), in turn implying emissions other than water. Water would still be frozen at that far out from the Sun. Truly, an object worth observing.