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Last Updated 2018-08-

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Changes since last version of the release notes (changes bolded in text below):

2018-08-20: 1) Description added for disposition (column 86) and duplicate ID (column 87) columns.

                     2) Update to changes compared to TIC-6 to denote the disposition (column 86) and duplicate_id (column 87) columns now have entries. Previously, these columns were null everywhere.

Introduction

This delivery contains the seventh version of the TESS Input Catalog (TIC) produced entirely by the Target Selection Working Group (TSWG), and was finalized and prepared for delivery to the TESS Science Office (TSO) on 2018 June 17.

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1. Nearly all coordinates have been computed for epoch 2000.0, the exceptions are POSFlag (Column 16) hotsubdwarf (40 stars), and gicycle1 (1692 stars) for which an epoch for the coordinates was not provided to the Target Selection Working Group. For stars having been Gaia DR1 multiples in TIC-6 (POSFlag tmmgaia) we reverted to the 2MASS coordinates of the main component, and propagated the epoch given in 2MASS to 2000.0. Ecliptic and galactic coordinates (Column 25-28) have the same epoch as RA and Dec (Column 14 and 15).

2. Targets from the asteroseismology list, previously missing in the TIC, have been added to the TIC (278 stars)in the TIC, have been added to the TIC (278 stars).

3. The disposition (column 86) and duplicate_id (column 87) columns are no longer columns without entries in TIC-7.
   

4. CTL6 stars with POSFlag (Column 16) hip and lepine have been rematched. 37 duplicates were identified. These stars were in TIC6 twice, once for hipparcos and once for 2MASS. Duplicates and artifacts have been deleted from the CTL and flagged as such in TIC. The disposition and duplicate_id column (Column 86 and 87) point to the valid TIC-entry for every duplicate. The artifacts are stars from an earlier version of Superblink which do not occur in any later version of Superblink.

5. The 329 Hipparcos stars which are not in the CTL, have been propagated to epoch 2000.0, but have not been rematched. It is possible many of these stars are duplicates, but due to time constraints, they could not be matched by hand. These will be updated with the Gaia DR2-based TIC-8.

6. All CTL-stars now have a contamination ratio. Where a priority could not be computed due to missing information, the contamination ratio may serve as a guide for the suitability of target selection.

7. The 13 stars in TIC-6 which did not have TESS magnitudes, now have proper non-null values.

8. Stars in the specially curated cool dwarf list were updated, and their stellar parameters have changed. Users are encouraged to double check the stellar parameters for these stars have been updated with the SPflag = ‘cdwrf’ (Column 64).

9. Stars in the specially curated known planet host list now have their stellar parameters updated. Users are encouraged to investigate these parameters using the SPflag = ‘kplnt’ (Column 64).

10. The legacy SPflag = ‘allen’, have been replaced with ‘splin’ to properly reflect the source of the stellar parameters. Similarly, SPflag = ‘spect’ has been replaced with ‘spec.’

11. Stars in TIC-6 which had luminosity errors larger than the luminosity value, now show luminosity errors equal to the luminosity value.

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85   contratio   The contamination ratio is defined as the nominal flux from the contaminants divided by the flux from the source. Flux contamination is calculated for all stars in the CTL. Contaminants are searched for within 10 TESS pixels of the target and the contaminating flux is calculated within a radius that depends on the target’s TESS magnitude (Tmag, column 61). The PSF is modeled using a 2D-Gaussian based on preliminary PSF measurements from the SPOC. See section 3.2.3 of the full documentation for details.

86disposition  This column identifies objects which are included in the TIC, but are likely spurious. Currently, this column is populated with NULL, DUPLICATE, or ARTIFACT.

87duplicate_idThis column points to the TIC ID of the ‘other’ object in an ARTIFACT or DUPLICATE pair.

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 for CTL7.1 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, epsilon = 0 contamination and sigma = 61.75 ppm.

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