Mission Overview
TESS Image CAlibrator Full Frame Images ("TICA")
Primary Investigator: Michael Fausnaugh
HLSP Authors: Michael Fausnaugh, Christopher Burke, George Ricker, Roland Vanderspek
Released: 2021-02-02
Updated: 2023-03-22
Primary Reference(s): Fausnaugh et al. 2021
Citations: See ADS Statistics
Overview
TESS images that serve as the input to the MIT Quick Look Pipeline (QLP) are provided here. The team uses a Python package ("tica"), to calibrate the raw pixels and apply astrometric registration in the form of World Coordinate Solutions. The team has also made the "tica" code available publicly on Github (github.com/mmfausnaugh/tica). MAST does not own or maintain this software repository, and takes no responsibility for its performance or quality, but provides a link to it here to the software "as-is" for convenience. Questions about the code should be directed to the project owner, Michael Fausnaugh at faus@mit.edu, and bug reports should be directed to the TESS help desk at tesshelp@bigbang.gsfc.nasa.gov.
TICA product cutouts are available via the TESSCut user interface.
Data Notes
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During Sector 60, Orbit 1a, due to incomplete contacts, there are fewer FFIs available for each CCD in Camera 1. All other cameras (Cameras 2-4) have 2940 FFIs in this half-orbit for each CCD, while Camera 1 only has 2939 FFIs for each CCD.
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During Sector 57, TESS entered into safe mode, suspending science observations. As a result, there is one fewer file (for all CCDs) available in TICA Sector 57, Orbit 1b, Camera 4, which corresponds precisely with when the safe mode started during Orbit 1b.
Data Delivery
The concept of a "Data Release" was stopped due to the regular cadence of data delivery. For Sector 35 and beyond, data are delivered to MAST as soon as feasible after the completion of each Orbit. Starting with Sector 56, data are delivered every half-Orbit, as denoted by the Orbit Part.
Data Release 1 - 02 February 2021
The first data release consists of quick-look calibrated full frame images from Sectors 27 - 30.
Data Release 2 - 08 March 2021 and 12 March 2021
The second data release consists of quick-look calibrated full frame images from the first Orbit of Sector 35. Quick-look data from the second Orbit of Sector 35, released a few days later, include observations that were completed on March 6, 2021. Additional information about the Sector 35 FFIs will be provided in the formal Data Release Notes when Sector 35 is fully ingested into MAST.
Data Products
All TICA calibrated full frame image files are sorted into directories based on the Sector, as a four-digit, zero-padded string preceded by an 's'. They are then further sorted into subdirectories based on the Camera and CCD numbers. For example, the files associated with Sector 27 for Camera 2, CCD 3, go into this subdirectory:
s0027/cam2-ccd3/
The catalog of reference stars used to define the WCS are stored in a subdirectory called "ref-stars/" within each Sector directory.
The calibrated full frame images have the following naming convention:
hlsp_tica_tess_ffi_<sector>-<orbit>-<cadence>-<cam>-<ccd>_tess_v01_<extension>
where:
- <sector> = The Sector number as a four-digit, zero-padded number preceded by an 's', e.g., 's0027' for Sector 27.
- <orbit> = The relative orbit number within this Sector, either "o1" or "o2". Note that this does not correlate to the absolute Orbit Number that is tracked and reported in the Data Release Notes and in mission-produced products.
- <cadence> = The cadence number, as an eight-digit, zero-padded integer, equal to the FFIINDEX header keyword for mission-produced FFIs.
- <cam> = The camera number (1-4), e.g., "cam2" for Camera #2.
- <ccd> = The CCD number (1-4) for that camera, e.g., "ccd1" for CCD #1.
- <extension> = "img.fits" for the calibrated full frame images.
The WCS calibration reference star catalogs have the following naming convention:
hlsp_tica_tess_ffi_<sector>-<cadence>-<cam>-<ccd>_tess_v01_<extension>
where:
- <sector> = The Sector number as a four-digit, zero-padded number preceded by an 's', e.g., 's0027' for Sector 27.
- <cadence> = The cadence number, as an eight-digit, zero-padded integer, equal to the FFIINDEX header keyword for mission-produced FFIs.
- <cam> = The camera number (1-4), e.g., "cam2" for Camera #2.
- <ccd> = The CCD number (1-4) for that camera, e.g., "ccd1" for CCD #1.
- <extension> = "cat.h5" for the catalogs of stars used to refine the World Coordinate System for the TICA full frame images.
Data file types:
| _img.fits | Calibrated full frame image. |
| _cat.h5 | Catalog of stars used to refine the WCS for a given Sector+Camera+Chip. These file formats are in HDF5. |
Description of FFI Header Keywords
Click "Expand All" to see the FITS header information.
| Keyword | Header Card | Notes |
|---|---|---|
| CRM_N | Window for CRM min/max rejection | For each pixel, the high and low value in a series of "CRM_N" 2-second exposures are rejected in order to remove cosmic rays. |
| ORBIT_ID | Orbit ID, not a physical orbit | Only unphysical for commissioning or engineering data. |
| ACS_MODE | Attitude Control System mode | Either "FP" for Fine Pointing mode or "CPI" for Course Pointing Inertial mode. |
| SC_RA | Predicted RA | Commanded pointing for the Spacecraft. Note that orbit 2 is shifted a few arcseconds relative to orbit 1. |
| SC_DEC | Predicted Dec | Commanded pointing for the Spacecraft. Note that orbit 2 is shifted a few arcseconds relative to orbit 1. |
| SC_ROLL | Predicted roll | Commanded pointing for the Spacecraft. Note that orbit 2 is shifted a few arcseconds relative to orbit 1. |
| SC_QUATX | Predicted S/C quaternion x | Commanded pointing for the Spacecraft. Note that orbit 2 is shifted a few arcseconds relative to orbit 1. |
| SC_QUATY | Predicted S/C quaternion y | |
| SC_QUATZ | Predicted S/C quaternion z | |
| SC_QUATQ | Predicted S/C quaternion q | |
| TJD_ZERO | JD-TDB epoch for which TJD = 0 | Corresponds to 2014 December 8 12-00-00 UTC. |
| STARTTJD | Beginning of integration in TJD (days) | Time system is in the spacecraft reference frame. |
| MIDTJD | Mid TJD of exposures | |
| ENDTJD | End of integration in TJD | |
| EXPTIME | Effective exposures corrected for CRM |
Equal to "INT_TIME"*0.8*0.99. Includes the effects of cosmic ray mitigation and frame transfer. |
| INT_TIME | Seconds of integration | Total seconds after integration of 2 second exposures. |
| PIX_CAT | ADHU target pixel bitmask ID | Spacecraft configuration table. |
| REQUANT | Requant table id | Spacecraft configuration table, used for data compression. |
| DIFF_HUF | Huffman table for differenced data | Spacecraft configuration table, used for data compression. |
| PRIM_HUF | Huffman table for undifferenced data | Spacecraft configuration table, used for data compression. |
| QUAL_BIT | Quality flags | Place-holder field; currently not implemented. |
| SPM | SPM number (0, 1, 2, 3) | Science Processing Module. Each TESS data mode is collected by a different SPM number. For the FFIs, SPM=2. |
| TIME | Beginning of integration in SCT (seconds) | Second counter for spacecraft on-board clock. |
| CADENCE | Cadence number since start of data collection | Cadence 0 is approximately defined as the time that TESS was launched, 2018 April 18 23-00-00 UTC. |
| CRM | Whether or not cosmic ray were mitigated | If true, cosmic rays were mitigated on-board. |
| ORB_SEG |
Orbit Identifier, o1a, o1b, o2a, o2b |
Introduced for TESS Extended Mission 2, identifies which half (a, b) of the orbit (1, 2) |
| CAMNUM | Camera Number | Camera Number (1 through 4). |
| CCDNUM | CCD number | CCD number (1 through 4). |
| SCIPIXS | Pixel indices with science data. Pixels outside of this region are collateral pixels, used for calibration. Always equal to "[45:2092,1:2048]". | |
| GAIN_A | e/ADU for CCD Sector A | Conversion factor of ADU to photoelectrons. |
| GAIN_B | e/ADU for CCD Sector B | |
| GAIN_C | e/ADU for CCD Sector C | |
| GAIN_D | e/ADU for CCD Sector D | |
| UNITS | Units (ADU or electrons) | Always equal to "electrons". |
| EQUINOX | Always set to epoch 2000.0. | |
| INSTRUME | Always set to "TESS Photometer". | |
| TELESCOP | Always set to "TESS". | |
| FILTER | Always set to "TESS". | |
| MJD-BEG | Same as STARTTJD but in JD. | |
| MJD-END | Same as ENDTJD but in JD. | |
| TESS_X | Spacecraft X coord, J2000 (km from barycenter) | Position of TESS used for barycentric correction. Matches SPICE conventions: axes are aligned with J2000 ICRS, but the origin is centered at the solar system barycenter. X-axis points at vernal equinox. |
| TESS_Y | Spacecraft Y coord, J2000 (km from barycenter) | As above. Y-axis is orthogonal to X. |
| TESS_Z | Spacecraft Z coord, J2000 (km from barycenter) | As above. Z-axis points at north celestial pole. |
| TESS_VX | Spacecraft X velocity (km/s) | Velocity relative ot barycenter. |
| TESS_VY | Spacecraft Y velocity (km/s) | Velocity relative ot barycenter. |
| TESS_VZ | pacecraft Z velocity (km/s) | Velocity relative ot barycenter. |
| RA_TARG | Right Ascension of center of image [deg.]. | Same as CRVAL1, matches MAST convention. |
| DEC_TARG | Declination of center of image [deg.]. | Same as CRVAL2, matches MAST convention. |
| RMSA | WCS fit resid all targs [arcsec] | Metric for quality of WCS fit. |
| RMSB | WCS fit resid bright (Tmag<10) targs [arcsec] | |
| RMSF | WCS fit resid faint (Tmag>10) targs [arcsec] | |
| RMSAP | WCS fit resid all targs [pixel] | |
| RMSBP | WCS fit resid bright (Tmag<10) targs [pixel] | |
| RMSBF | WCS fit resid faint (Tmag>10) targs [pixel] | |
| RMSX0 | WCS fit resid extra 0 [arcsec] | |
| RMSX1 | WCS fit resid extra 1 [arcsec] | |
| RMSX2 | WCS fit resid extra 2 [arcsec] | |
| RMSX3 | WCS fit resid extra 3 [arcsec] | |
| WCSGDF | Fraction of control point targs valid | |
| CTRPCOL | Subregion analysis blocks over columns | For efficient searching, queries to MAST are broken into subregions. |
| CTRPROW | Subregion analysis blocks over rows | As above. |
| FLXWIN | Width in pixels of Flux-weight centroid region | |
| CHECKSUM | HDU checksum | |
| DATASUM | Data unit checksum |
Data Access
TESSCut
NEW! TICA FFIs are available via the TESSCut service. To use TICA data when making your cutout, select "TICA" under the "Product" drop-down.
There are some key differences between the cutouts created from the Science Processing Operations Center (SPOC, i.e., TESS Mission) and the TICA products, as detailed here:
- In the TICA FFIs, and the resulting cutouts, flux measurements are given in units of electrons, 'e-'. For SPOC, flux is given in units of 'e-/s'.
- TICA FFIs do not include data quality flags.
- The TICA calibration pipeline does not propogate errors. As such, the TICA FFIs do not give a measurement of the flux error.
- Because the TICA and SPOC products are calibrated using different pipelines and different WCS solutions, there are small, but statistically significant offsets in the physical and WCS alignment between SPOC and TICA cutouts. For most applications, these differences will be unimportant, but users that require very accurate astrometry (<2'', or ≲0.1 pixels) should be aware of these offsets.
NOTE: After TICA FFIs are available vua bulk download, it takes several days for those same FFIs to become available via the TESSCut user interface.
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Make a cutout of a TICA FFI time series for a region of the sky.
Bulk Downloads
The calibrated full frame images and catalogs of WCS reference stars are also available as bulk download scripts for each Sector, via the table below. In Sectors 27 through 55, each Sector is broken into two Orbits (Orbit 1 and Orbit 2), as there are two contacts for data downlink with the TESS spacecraft during these Sectors. Starting in Sector 56, there are two contacts with the TESS spacecraft per Orbit, such that each Orbit is broken up into two segments or "Parts". In the table below, Sectors 56 and beyond are each broken into four parts: Orbit 1, Part a; Orbit 1, Part b; Orbit 2, Part a; Orbit 2, Part b.
The scripts use curl, which is likely already installed on many machines, and if not, is freely available as open source software. The bulk download scripts for the mission-produced products also make use of curl. You can run each shell script directly in a terminal to retrieve the full set of files, or use a selected subset of the script: each line in the script downloads one TICA file.