LcTools Product Description

1. Introduction

LcTools is a Windows-based set of applications for finding, recording, and viewing signals in light curves for supported missions and associated HLSPs (High Level Science Products) at MAST. Supported missions include TESS, K2, and Kepler. Supported HLSPs include QLP, TESS-SPOC, and GSFC-ELEANOR-LITE for the TESS mission and K2SFF and EVEREST for the K2 mission. The system consists of the following applications:

 display, and phase fold signals.

 in addition to pre-recorded signals for project-based and community-based 

 planetary objects of interest (TOIs, CTOIs, K2OIs, and KOIs).

A high level overview of features provided is presented below. See the LcTools research paper for system details.

2. LcViewer

2.1 Overview

LcViewer is a multi-purpose graphics based application designed for processing light curves and their signals. Using LcViewer you are able to 1) build, view, edit, and detrend light curves, 2) detect, record, measure, display, query, locate, and phase fold signals, 3) import and display project based signals including TOIs, CTOIs, K2OIs, KOIs, and TCEs, 4) automatically align TTV shifted transits in project based signals, 5) detect, record, and display TTVs, 6) display background flux, 7) measure time and flux intervals, and 8) query stellar properties. Both periodic and non-periodic signals are supported. Signals may be dips or peaks.

The application provides advanced light curve navigation and display features with multiple ways to select views, pan, and zoom. Navigation also includes auto-scrolling, real-time tracking of the current position and signal at the cursor, and the ability to save and restore views.

2.2 Sample Screen Snapshots

The following screen snapshots will help illustrate some of the key features listed above.

Snapshot 1: The “Open Lightcurve” dialog box. Enables you to specify the light curve directory, star ID, and light curve file to generate or open for a project.

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Snapshot 2: The “Time Series Selection” dialog box. Enables you to specify the time series periods, cadence, flux type, data point quality filter, short cadence bin size, and filename of a light curve file to build.

As part of the build process for a light curve file, LcViewer:

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Snapshot 3: A Kepler light curve showing a highlighted planetary transit signal. Project defined signals are obtained from MAST, NEA, or ExoFOP-TESS as applicable and include TOIs, CTOIs, K2OIs, KOIs, and TCEs.

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Snapshot 4: The Tracking Information Box showing the time, flux, and signal at the cursor. Values are updated in real-time.

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Snapshot 5: Two overlapping KOI transit signals. LcViewer automatically marks the overlapping region of mutual signals in red.

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Snapshot 6: A TTV shifted planetary transit signal. Signals can be aligned in three ways: 1) automatically using imported TTV libraries, 2) automatically using the QuickFind signal detection method, and 3) manually using the mouse.

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Snapshot 7a: Measuring the time interval between two candidate signals in the light curve.

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Snapshot 7b: Measuring the depth and signal size for a candidate signal in the light curve.

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Snapshot 8a: A Kepler SAP_FLUX light curve to be detrended.

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Snapshot 8b: Same light curve with a fitted trend line plus associated dialog box for controlling the detrending operation.

Via the dialog box, you can:

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Snapshot 8c: The detrended light curve after the Detrend button is clicked.

You can click the Redo button to retry the detrending operation using different settings. The Redo button can also be used to quickly compare the before and after images to see what changed.

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Snapshot 9a: Preparing to search for periodic signals in a Kepler light curve using the QuickFind signal detection method.

Via the dialog box, you can:

Before a signal search is started, the data points for all defined signals are removed from the light curve so that already known signals are not found again.

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Snapshot 9b: A detected periodic signal highlighted in green plus an accompanying dialog box for controlling the signal detection operation.

Via the dialog box and light curve you can:

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Snapshot 9c: Preparing to phase fold the selected periodic signal.

Via the dialog box, you can:

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Snapshot 9d: The phase folded light curve for the selected signal plus accompanying dialog box for controlling the phase fold operation.

The small grey dots represent the unbinned data points. The large green dots represent the binned data points. Via the dialog box, you can:

A phase folded light curve can be saved to a file and then opened at a later time just like a regular light curve. You can also measure and create user defined signals in the phase folded light curve.

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Snapshot 9e: Creating (recording) a user defined EB-P signal in a private signal library. Associated TTVs are recorded in a default TTV library. Note that the dialog box is populated automatically.

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Snapshot 9f: The created EB-P signal.

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Snapshot 10: A TTV diagram (aka, O-C diagram) for a periodic signal in a light curve.

A TTV diagram can be displayed for any periodic signal in a light curve having recorded TTVs. Each data point in the diagram shows the time difference in hours between the observed (detected) instance and the calculated instance in the light curve. 

If there are any significant outliers in the plot such as the one shown at 373.8 BKJD above, you can double-click on the outlier and you will be returned to the regular light curve with the view centered at the corresponding instance of the signal in the light curve. You can then either move the color coded instance manually using the mouse or delete the color coded instance in an effort to resolve the outlier.

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Snapshot 11: Setting Up a Work Group for a TESS light curve directory.

A work group is a set of light curve files that you wish to view or process in LcViewer. You can select files based on a file filter, a build list, a star list, a file list, or from the files having signals from LcSignalFinder. For example, a work group could contain all the TESS CTL light curve files in a TESS sector typically consisting of 20,000 files. 

Once a work group is set up, files can be quickly loaded (opened) from the work group in sequential order by clicking the "Next" button at the bottom left corner of the main application window. This is a fast, easy, and efficient alternative to the "Open Lightcurve" dialog box. Ideal for iterating though a large list of files.

3. LcSignalFinder

LcSignalFinder detects and records signals and associated TTVs found in a large set of light curve files for subsequent use with LcViewer. Signals may be periodic or non-periodic, dips or peaks. For example, LcSignalFinder can be used to find and record periodic signals and associated TTVs in the TESS CTL light curve files for an entire TESS sector typically consisting of 20,000 files. A sample application window is shown below:

Via the application window you can:

LcSignalFinder works in conjunction with LcViewer. While LcSignalFinder is executing, LcViewer can be used to vet the signals previously recorded by LcSignalFinder. By running both applications concurrently, processing time across the set of files can be minimized.

4. LcGenerator

LcGenerator builds light curve files in bulk for subsequent use with LcViewer and LcSignalFinder. For example, LcGenerator can be used to build TESS CTL light curve files for all the stars in a TESS sector typically consisting of 20,000 files. A sample application window is shown below:

Via the application window, you can:

As part of the build process for a light curve file, LcGenerator:

5. LcReporter

LcReporter generates Excel reports for signals recorded by LcSignalFinder and LcViewer in addition to pre-recorded signals for project-based and community-based planetary objects of interest (TOIs, CTOIs, K2OIs, and KOIs). A partial sample report for candidate signals and associated TTVs recorded by LcSignalFinder in a light curve directory is shown below:

6. Run-Time Requirements (Minimum)

7. Contact Information

To obtain this product for use or to learn more about it, please contact the author at aschmitt@comcast.net.

Acknowledgements 

I would like to sincerely thank the following individuals for contributing to this product: