The TESS mission has several data products ranging from the TESS input catalog to a catalog of planet candidates. Here we give an overview of what information is in each data product, how it is produced and how the data is formatted.
Photometric Data Products
TESS obtains time-series photometry at two different cadences with a baseline ranging from 3 weeks out to a year. An overview of the primary science products are shown above. The entire set of CCDs for each TESS sector are downloaded every 30-minutes, these are known as the Full Frame Images (FFIs). Certain groups of pixels are also downloaded at a 2-minute cadence in order to obtain a faster cadence for a subset of targets. The pixels around a selected star are stored as arrays in target-pixel files, one image per time stamp. Aperture photometry is performed on each image creating an array of fluxes; these are stored in a light curve file. See the Science Product Handbook for more detailed information on file formats and content.
- Full Frame Images (FFI, ffi.fits): These files contain the long cadence time series of the entire field of view, both an uncalibrated and calibrated version are available.
- Target Pixel Files (TPF, .tp.fits): These files contain a time series of the raw and calibrated pixels downloaded at the 2-minute cadence.
- Light Curve Files (LCF, .lc.fits): These files contain the flux time series derived from the calibrated short-cadence pixels. These files contain several time series including the simple aperture photometry, a detrended light curve, position vectors and quality flags.
- Cotrending Basis Vectors (CBV, .cbv.fits): The cotending basis vectors represent the set of systematic trends present in the ensemble light curve data for each CCD and can be used to remove common instrumental systematics from the data. These vectors are created by the pipeline to create the detrended flux time series in the light curve files.
Target Catalogs
TESS provides several catalogs of target stars in order to choose which stars will be observed at the 2-minute cadence.
- TESS Input Catalog (TIC): Catalog of stars created by the TESS Stellar Properties Working Group and is used to select targets to download at short cadence. The TIC is available through the MAST portal and via the API.
- Catalog Target List (CTL): Several lists of TIC stars that idicate the priorities for short-cadence observations from different science perspectives. The same TIC ID may appear in more than one list.
- Merged Target List (MTL): This list represents the targets that are observed at the 2-minute cadence. It is created by merging the CTLs plus specific engineering targets.
Planet Search Products
The flux time series for each star observed in short cadence are then further detrended and searched for transits. The repeating signals that are identified in this way are known as Threshold Crossing Events (TCE). The following products are produced by the TESS Science Processing Pipeline for each target star that produces a TCE.
- DV Time Series File (.dvt.fits): These files contain the sector-stitched, detrended and whitened light curves searched by the TESS Pipeline. All TCEs found on a star in one search are contained in the same file.
- DV Report (.dvr.pdf): These pdf files contain plots and statistics for each TCE. For example, the reports contain plots of folded light curves and in- and out-of transit difference images.
- DV One-Page Summary (.dvs.pdf): This one page summary contains a quick overview of each TCE and much of the most important information about the TCE to determine if the signal is likely caused by a transit or shows evidence of being caused by an eclipsing binary or instrumental noise. Each TCE gets its own file, so if multiple TCEs are found on the same target star, there will be multiple pdf files.
Exoplanet Result Catalogs
TESS produces several catalogs of possibly transit-like, periodic signals found in the TESS data. As signals are vetted they are can be included in the next catalog down. The catalog of signals with the least amount of vetting are the Threshold Crossing Events (TCEs) which are produced by the SPOC Pipeline. Other groups may also search the short cadence light curves, or the longer cadence FFIs for signals that may be consistent with transiting exoplanets. Since these signals have little-to-no vetting, the reliability can be quite low. Signals found in the data are then turned into TESS Objects of Interest (TOI) once the signal is vetted and determined to be sufficiently consistent with a transit or eclipse. The TOI list contains both planet candidates and false positives, but these are the signals that are worthy of follow-up observations. Once follow-up measurements, or additional analysis, reveal the mass of the transiting object, or remove all doubt that the signal could be caused by an eclipsing binary, the planet is considered confirmed.
- Threshold Crossing Events (TCE): Table of TCE signals and various metrics that measure different aspects of that signal. For each TCE, the project provides a highly detrended light curve file and a report showing relevant plots to evaluate whether the signal is a planet. The project also provides an xml file for each star that contain all the information related to the TCEs found in that star's light curve. These signals are not vetted and include various types of false positives and instrumental false alarms. Each TCE is identified by a TIC ID, planet number and search ID.
- TESS Objects of Interest (TOI): Table containing the list of signals that are consistent being a transiting planet. This catalog provides a disposition of either planet candidate or false positive which can change as more information is gathered about a target from follow-up and additional analysis of the data.
- Confirmed Planets: Transiting planets found in the TESS data for which follow-up data provide a mass of the planet. See the exoFOP-TESS page for more information about what follow-up data are available.
Engineering Files
- Collateral Pixel Files (*-{lvcol, smrow, tvcol, vrow}-*col.fits)
- Models (Huffman tables, Mean Black table, flat-field, read-noise, linearity, gain, etc.)