## Mission Overview

### TESS-Gaia Light Curve ("TGLC")

Primary Investigator: Timothy D. Brandt

HLSP Authors: Te Han

Released: 2023-01-19

Updated: 2023-03-31

Primary Reference(s): Han & Brandt 2023

## Overview

TESS-Gaia Light Curve (TGLC) is a PSF-based TESS full-frame image (FFI) light curve product. Using Gaia DR3 as priors, the team forward models the FFIs with the effective point spread function to remove contamination from nearby stars. The resulting light curves show a photometric precision closely tracking the pre-launch prediction of the noise level: TGLC's photometric precision consistently reaches ≲2% at 16th TESS magnitude even in crowded fields, demonstrating excellent decontamination and deblending power.

The HLSP authors publish TGLC Aperture and PSF light curves for stars down to 16th TESS magnitude for all available sectors and will continue to deliver future light curves. The authors also publish an open-source package tglc, which can be used to produce similar quality light curves for any sector and any star with custom options. For the quickest access to light curves from newly released TESS sectors, the team recommends that users run the tglc package. 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.

#### Data Notes

In the primary TESS Mission (Sectors 1 through 26) light curves provided by the TGLC team, in cases where the target star is very dim (≲15 Tmag) and near a variable source, the aperture and/or PSF light curve may be negative for some cadences. The subsequent detrending algorithm may malfunction and result in bad cal_aper_flux and/or cal_psf_flux values. This issue now fixed for the tglc package and will be applied to future TGLC data releases, but this problem remains for the primary Mission light curves published on MAST. Users should detrend these light curves if necessary.

## Data Products

The light curve files have this data file naming convention:

hlsp_tglc_tess_ffi_gaiaid-<gaiaid>-s<sector>-cam<cam>-ccd<ccd>_tess_v1_llc.fits

where:

• <gaiaid> = The full Gaia DR3 source ID, e.g., "6483604294135323520".
• <sector> = The Sector represented as a 4-digit, zero-padded string, e.g., "s0004" for Sector 4.
• <cam> = The camera number (1-4), e.g., "cam1" for Camera 1.
• <ccd> = The CCD number (1-4) for that camera, e.g., "ccd1" for CCD 1.

Data file types:

 _llc.fits Extracted light curve file

## Data Access

TGLC light curves are available via the MAST Portal web search and the astroquery python package.  Set "Provenance Name" to "TGLC" in the Portal's Advanced Search if you wish to restrict results to TGLC.  You can also use the "Sequence Number" to limit the search to a specific Sector. You can also search on TESS Input Catalog (TIC) ID using the "Target Name" field in Advanced Search. Alternatively, to search on Gaia DR3 ID, you can search for "hlsp_tglc%<gaiaid>%" in the Observation ID field. NOTE: the interactive plot tool in the Portal does not currently work for TGLC HLSP light curves.

* The TGLC light curves for Sectors 4-7 are not yet available via the MAST Portal, API, or astroquery, but can be accessed for bulk download via the provided curl script in the table below.

• ### MAST Portal

A web-based interface for cross-mission searches of data at MAST or the VO. Download a small number of TGLC light curves.
• ### MAST Astroquery

Search for, and retrieve, TGLC data products programmatically in python based on a list of coordinates or target names.

For bulk downloads of TGLC light curves, we recommend utilizing the bulk download scripts for each Sector, provided in the table below.  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 TESS Mission light curves 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 TGLC file.

TESS Sector Number of Light Curves Total Data Volume Bulk Download Script
1
2,481,050
0.9 TB
2
1,973,987
0.6 TB
3
1,837,696
0.6 TB
4 *
1,942,827
0.6 TB
5 *
2,582,658
0.6 TB
6 *
5,517,576
1.5 TB
7 *
8,116,193
2.2 TB

## Citations

Please remember to cite the appropriate paper(s) below and the DOI if you use these data in a published work.

Note: These HLSP data products are licensed for use under CC BY 4.0.