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88    priority      Priority of target for observation. This is a floating-point value ranging from 0 to 1, where 1 is highest priority. The priority is based on the relative ability of TESS to detect small planetary transits, and is calculated using the radius of the star, the contamination ratio, and the total expected photometric precision. Stars are given a boost factor to their priority which scales with a probabilistic model of the expected number of sectors any given star could fall in. Typically, the closer the star is to the Ecliptic North or South pole, the larger the boost factor. Stars close to the Galactic Plane (|b|<15) have been de-boosted by a factor of 0.1 since we generally have a poor understanding of their true reddening, unless they are in the specially curated Cool Dwarf list (see Muirhead et al. 2017). The formula is for CTL 6.1 was defined as:  sqrt(Ns)/(R1.5*sqrt(epsilon+1)*sigma) where Ns is the expected number of  TESS sectors to observe the star; R is the radius of the star (column 71), ε epsilon is the contamination ratio (column 87) and 𝛔 sigma is the expected photometric precision of the star based on the TESS magnitude (column 61). The formula for CTL 6.2 is defined as: sqrt(Ns)/(R1.5*sigma) where Ns is the expected number of  TESS sectors to observe the star; R is the radius of the star (column 71), and sigma is the expected photometric precision of the star based on the TESS magnitude (column 61) using the formulation from Sullivan et al. 2015. The priority is normalized by the priority for a star with R = 0.1 solar, Ns = 12.654 sectors, ε epsilon = 0 contamination and 𝛔 sigma = 61.75 ppm.

Some stars will have distinct priorities:

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