TESS centroid_vetting

Overview

TESS-Centroid_vetting provides photometric centroid offset analysis for vetting exoplanet candidates identified in TESS (Transiting Exoplanet Survey Satellite) data.
It was inspired by the graphical representation of the centroid in the Data Validation (DV) reports of Threshold Crossing Events (TCEs) produced by the TESS Science Processing Operations Center (SPOC) pipeline
The centroid representation allows identifying the source of the dips in a light curve, discarding potential false positives and identifying possible sources of contamination.
It is an open-source Python package that can analyze any TESS Target Pixel File.

Method

The method is similar to the centroid offset analysis in TESS SPOC TCE DV reports, which measures centroids using difference imaging with PRF-based (pixel response function) centroid fitting.

TESS-Centroid_vetting lets users customize some parameters to handle edge cases, including:

• Pixel masking: ignores selected pixels during calculation, which helps avoid pixels that could skew the results (e.g., a nearby variable star).
• In-transit / out-of-transit duration: can be customized to avoid problematic cadences.

Current limitations (v1.4.0):

• The centroid uncertainties are not available.
• Multi-sector centroid fitting is not available.

Comparability with TESS TCE DVs: it has been evaluated in an ad-hoc basis that the result from TESS-Centroid_vetting is comparable to TESS TCE DVs. However, it has not been systematically evaluated yet.

Documentation

Read the docs generated by DeepWiki:

Installation

Since version 1.2.0, a package is available at PyPi: So, the simplest way of installing TESS-Centroid_Vetting is using pip:

pip install tesscentroidvetting

Dependencies:

• numpy
• matplotlib
• astropy
• astroquery
• scipy
• lightkurve
• ipywidgets - only needed if interact=True in show_transit_margins()

Usage

See the notebooks in Examples directory for usage.

Acknowledgments

Sam Lee (https://github.com/orionlee) for implementing star's proper motion correction and transit margins display function, advising and testing.

Michelle Kunimoto (https://github.com/mkunimoto) for writing TESS-Plots, whose code was used for the PRF centroid calculation.

Last but not least, Nora Eisner for Planet Hunters Coffee Chat series, introducing python for exoplanet detection (the difference image calculation was first borrowed from there), and for Planet Hunters TESS citizen project, whose community forum is an invaluable source of knowledge and place to exchange views between amateurs and experts.

Contributors

Rafael Rodrigues, Sam Lee

References

TESS TCE DVs are described in:

• Twicken et al. 2020, TESS Science Data Products Description Document, https://archive.stsci.edu/missions/tess/doc/EXP-TESS-ARC-ICD-TM-0014-Rev-F.pdf

Their centroid offset analysis, based on the one developed for the Kepler mission, is described in:

• Twicken 2019, Data Validation: Difference Imaging and Centroid Analysis, https://ntrs.nasa.gov/citations/20190029148
• Bryson et al. 2013, Identification of Background False Positives from Kepler Data, https://iopscience.iop.org/article/10.1086/671767