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Last Updated 2018-10-04

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

2018-10-04: 1) New section added ‘Updates to the TICv7 CTL’’

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                        3) Added definition of future ARTIFACT objects (defined in column 86: disposition) to ‘Planned Improvements to Future Versions.’

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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The design is the same as TICv6, in that the columns and their format are the same, but there have been additional changes compared to previous versions of the TIC. TIC IDs have not been changed, and all future deliveries of the TIC will use the same IDs for specific objects. New objects added to the TIC will always receive new IDs. Objects may be removed from the TIC, if they are found to be spurious, but TIC IDs will always be unique and a new TIC object will never receive the ID of an old TIC object.

Updates to the TIC-7 CTL

The current version of the TIC-7 CTL is version 2. The delivery occurred on 2018 August 29.

1. The Hot Subdwarf list was inappropriately excluded from CTL 7.01, and has been added to CTL 7.02.

2. There were ~96K stars which had proper motions in TIC-5 (and were identified as RPMJ dwarfs in TIC-5) which have been removed from CTL 7.02. These stars were removed from CTL 7.02 because they no longer have trustworthy proper motions due to TIC-7s updated preference schema.

3. There were ~2400 stars which were identified as giants using Gaia or Hipparcos parallax values, and these objects have been removed from CTL 7.02.

Changes compared to TIC-6

This delivery contains major changes in computed quantities compared to TICv6. It should be noted that the methods used to estimate a variety of stellar parameters are still under active development and can be affected by poor catalog photometry when there is no acceptable alternative photometry for a given star. The major changes compared to previous versions are:

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 TICv6 (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).

3. The disposition (column 86) and duplicate_id (column 87) columns are no longer columns without entries in TICv7.
   

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 TICv6 which had luminosity errors larger than the luminosity value, now show luminosity errors equal to the luminosity value.

Notes on the individual columns

No.      Name       Notes

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d. Stars within the known planet list without a radius had their priority values set to 0.

Known Issues and Quirks:

There are a number of minor issues which have been identified by the TSWG. We expect to address these issues in a future version of the TIC. The issues include:

1. Because some stars have poor quality 2MASS photometry flags (such as ‘D’, ‘U’), offsets where applied to G, V, J, H, or Ks magnitudes to provide a more realistic TESS magnitude but may be different from the true value by a magnitude or more.  

2. The error in the luminosity currently only reflects the effect of the radius error but should also include the effects of temperature.

3. In some cases the density error is larger than the density itself, these errors should be interpreted as equal to the density.

4. Due to the preference of proper motion catalogs which are based on PPMXL, there is structure in the distribution of high priority candidates mainly above declinations larger than -30 deg.

5. Stars which have ecliptic latitudes between -6 and 6 degree have priorities set to 0, unless they are in the bright star list. This “gap” in priority is meant to mimic the expected gap in camera coverage for the 2 year primary TESS mission.

6. Some bright stars may have nearby impostor stars with similar magnitudes that lie along diffraction spikes from 2MASS photometry. Users can identify these impostors by checking 2MASS quality flags for very poor photometry (such as ‘D’, ‘E’, ‘F’, ‘U’). These objects should be removed in future versions of the TIC.

7. Some stars in the cool dwarf list and the known planet host list have effective temperature which are null, but still have calculated stellar parameters. These were adopted as is from each list for consistency.

8. Stars in the known planet list which did not have a radius, had their priority values set to 0.

9. Stars which were included in CTL7.01, but removed in CTL7.02 - see item 2 and 3 in Section ‘Updates to the TICv7 CTL’, still have stellar parameters in TICv7. These values are accepted to be unreliable, and users should disregard them. Links to tables with the appropriate TIC-ID for all of these objects can be found on MAST.
   

Planned Improvements in Future Versions:

There are a number of planned improvements for the future versions of the TIC. At present these improvements include:

1. Inclusion of all known exoplanets reported at the NASA archives with a full set of CTL parameters wherever this is possible and feasible.

2. In the future, the label ARTIFACT in the disposition column may refer to non-astrophysical objects such as diffraction spikes, image ghosting, bleed trails, or other similar phenomena.
   

Column Number, Column Name, Column Data Type and Brief Description:

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