The SPHERE infrared survey for exoplanets (SHINE): IV. Complete observations, data reduction and analysis, detection performances, and final results

Context: Over the past decade, large surveys with state-of-the-art planet-finder instruments such as Spectro-Polarimetric High-contrast Exoplanet REsearch on board Very Large Telescope (SPHERE@VLT), coupled with coronagraphic devices and extreme adaptive optics (AO) systems, have unveiled around 20 planetary mass companions at a semi-major axis greater than 10 astronomical units (au). Since direct imaging is the only detection technique with the ability to probe this outer region of planetary systems, the SPHERE infrared survey for exoplanets (SHINE) was designed and conducted from 2015 to 2021 to study the demographics of such young gas giant planets around 400 young nearby solar-type stars. The analysis of the first part of the survey focused on 150 stars (SHINE F150) was already published in a series of papers in 2021. An additional filler campaign called snapSHINE was conducted to acquire second epoch data, using shallow observations. Aims: In this paper, we present the observing strategy, data quality, and point source analysis of the full SHINE statistical sample as well as snapSHINE. Methods: Both surveys used the SPHERE@VLT instrument with the IRDIS dual band imager in conjunction with the integral field spectrograph (IFS) and the angular differential imaging observing technique. All SHINE data (650 datasets), corresponding to 400 stars, including the targets of the F150 survey, are processed in a uniform manner, with an advanced post-processing algorithm called PACO ASDI. An emphasis is put on the classification and identification of the most promising candidate companions. Results: Compared to the previous early analysis SHINE F150, the use of advanced post-processing techniques significantly improved the contrast detection limits by one or two magnitudes (x3-x6), which will allow us to put even tighter constraints on the radial distribution of young gas giants. This increased sensitivity directly sets SHINE apart as the largest and deepest direct imaging survey ever conducted. We detected and classified more than 3500 physical sources. One additional substellar companion was confirmed during the second phase of the survey (HIP 74865 B) and several new promising candidate companions are awaiting follow-up epoch confirmations.