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gaia data release 3 documentation

8.2 Properties of the input data

8.2.2 Comparison to the actual catalogue content

Not every transit selected in the input list goes unscathed through the different steps of the pipeline. At every stage, there are anomalies, rejections, and tests that progressively filter observations that cannot be processed to the end or do not pass the final quality tests. The overall statistics of the remaining transits solved in the astrometric solution of SSOs is given in Table 8.4. These are the numbers after the ultimate run of the SSO pipeline, but before the external validation of CU9. For the known asteroids, one has a global success rate of 91 % in terms of transits with a solution. This is only 73 % for the satellites because the background noise close to a giant planet is very large and the rejection rate is higher. The number of contaminants (spurious detections) is also important in the vicinity of a bright and extended planet, and the match of a transit to a satellite in the input list may be erroneous and this passage is eventually discarded for good reasons. There are 11 satellites, out of the 42 in the input list, without a single transit properly solved. Only 7 asteroids from the total of 156 838 belong to the same category.

Table 8.4: Summary statistics of the selected transits solved by the SSO astrometric chain
Input list Solved Lost
# # % # %
Known asteroids 3 513 248 3 211 947 91 301 301 9
- Pluto 23 23 100 0 0
- Charon 17 6 35 11 65
Satellites 999 729 73 270 27
Unmatched asteroids, 2 transits 1 796 1 103 62 693 38
Unmatched asteroids, 3 transits 2 726 2 438 89 288 11
Total 3 518 769 3 216 217 91 302 552 9