Correcting systematic effects in a large set of photometric light curves

By Omer Tamuz, T. Mazeh, S. Zucker. 2005

397 citations recorded by the source corpus.

We suggest a new algorithm to remove systematic effects in a large set of lightcurves obtained by a photometric survey. The algorithm can remove systematic effects, like the ones associated with atmospheric extinction, detector efficiency, or PSF changes over the detector. The algorithm works without any prior knowledge of the effects, as long as they linearly appear in many stars of the sample. The approach, which was originally developed to remove atmospheric extinction effects, is based on a lower rank approximation of matrices, an approach which was already suggested and used in chemometrics, for example. The proposed algorithm is specially useful in cases where the uncertainties of the measurements are unequal. For equal uncertainties the algorithm reduces to the Principal Components Analysis (PCA) algorithm. We present a simulation to demonstrate the effectiveness of the proposed algorithm and point out its potential, in search for transit candidates in particular.

Subfields: Applied Mathematics, Ecology, Statistical and Nonlinear Physics

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Citations in the corpus

The SARS algorithm: detrending CoRoT light curves with Sysrem using simultaneous external parameters (2010, methodology): “In the original Sysrem the starting point was deemed to be unimportant since Tamuz et al. (2005) claimed that in their simulations no matter what initial values were used, the same effect and coefficients were obtained.”
TRANSIT DETECTION IN THE MEarth SURVEY OF NEARBY M DWARFS: BRIDGING THE CLEAN-FIRST, SEARCH-LATER DIVIDE (2012, methodology): “…algorithms such as the Trend Filtering Algorithm (TFA; Kovács et al. 2005) and the principal component analysis-like Systematics Removal method (SysRem; Tamuz et al. 2005) were developed to remove trends that are present in multiple stars in a field and thus presumably not astrophysical.”
Design Considerations for a Ground-Based Transit Search for Habitable Planets Orbiting M Dwarfs (2007, background): “Most transit surveys show such red noise at levels of 3–6 mmag for untreated light curves, which can often be reduced to 1–2 mmag with decorrelation algorithms (Pont et al. 2007; Tamuz et al. 2005; Jenkins et al. 2000).”
THE XO PLANETARY SURVEY PROJECT: ASTROPHYSICAL FALSE POSITIVES (2010, methodology): “Two different methods were employed to correct photometric data for systematic errors: SysRem (Tamuz et al. 2005) and one described by McCullough et al. (2005).”
Transits and Occultations (2010, methodology): “g a few longitudinally-distributed networks to provide more continuous time coverage. Major efforts were made to automate the observations, and to develop algorithms for precise wide-ﬁeld photometry (Tamuz et al. 2005, Kova´cs et al. 2005) and transit detection (Kova´cs et al. 2002). Horne (2003) to”
The WASP Project and the SuperWASP Cameras (2006, methodology): “Rather than analytically trying to remove these, we use thesysrem algorithm discussed by Tamuz et al. (2005) to detrend the data.”
Carbon monoxide and water vapor in the atmosphere of the non-transiting exoplanet HD 179949 b (2014, methodology): “In previous work (de Kok et al. 2013b; Birkby et al. 2013), we have tested several ways of per- Article number, page 3 of 10 A&A proofs: manuscript no. hd179_final forming this task, including Singular-Value Decomposition and the Sysrem algorithm (Tamuz et al. 2005).”
Precise time series photometry for the Kepler-2.0 mission (2014, methodology): “We also tried using the wellknown SysRem algorithm (Tamuz et al. 2005), where the systematic trends are iteratively identified as the first principal component of the matrix constructed from all the light curves, and each trend is removed by linearly decorrelating the flux measurement for each star…”
Detection of water absorption in the day side atmosphere of HD 189733 b using ground-based high-resolution spectroscopy at 3.2 μm (2013, methodology): “We have employed the SYSREM algorithm (Tamuz et al. 2005; Mazeh et al. 2007), which is commonly used by transit surveys to de-trend light curves.”