LcTools: A Windows-Based Software System for Finding and Recording Signals in Lightcurves from NASA Space Missions
DDraft version October 18, 2019
Typeset using L A TEX twocolumn style in AASTeX63
LcTools: A Windows-Based Software System for Finding and Recording Signals in Lightcurves fromNASA Space Missions
Allan R. Schmitt, Joel D. Hartman, and David M. Kipping Citizen Scientist, 616 W. 53rd. St., Apt. 101, Minneapolis, MN 55419, USA, [email protected] Department of Astrophysical Sciences, Princeton University, 4 Ivy Ln, Princeton, NJ 08544, USA, [email protected] Department of Astronomy, Columbia University, 550 W 120th Street, New York, NY 10027, USA, [email protected]
ABSTRACTSince 2009, the Kepler, K2, and TESS missions have produced a vast number of lightcurves forpublic use. To assist citizen scientists in processing those lightcurves, the LcTools software systemwas developed. The system provides a set of tools to efficiently search for signals of interest in largesets of lightcurves using automated and manual (visual) techniques. At the heart of the system isa multipurpose lightcurve viewer and signal processor with advanced navigation and display capabil-ities to facilitate the search for signals. Other applications in the system are available for buildinglightcurve files in bulk, finding periodic signals automatically, and generating signal reports. Thispaper describes each application in the system and the methods by which the software can be used todetect and record signals. The software is free and can be obtained from the lead author by requestat [email protected].
Keywords: lightcurve generator, lightcurve viewer, signal detection, detrending, phase folding INTRODUCTIONLcTools is a Windows based software system for find-ing and recording signals in the lightcurves for supportedprojects and associated High Level Science Products(HLSPs) at MAST. Supported projects include TESS,K2, and Kepler. Supported HLSPs include TASOC,K2SFF, and EVEREST.A signal may be recorded for any type of astronomi-cal event, artifact, or anomaly detected in a lightcurvewhether periodic or non-periodic. Examples of transitbased signals include planets, eclipsing binaries, moons,rings, trojans, and comets.The system consists of four major applications – LcViewer, LcSignalFinder, LcGenerator, and LcRe-porter.
LcViewer is a multipurpose lightcurve viewerand signal processor enabling a user to 1) generate,edit, and detrend lightcurves, 2) detect, record, mea-sure, track, locate, query, and display signals, 3) im-port and display project based signals such as TOIs andKOIs, 4) record TTVs, 5) phase fold periodic signals,6) measure time and flux intervals, and 7) query stellarproperties.
LcSignalFinder automatically detects andrecords periodic signals found in large sets of lightcurves.
LcGenerator builds lightcurve files in bulk for subse-quent use with LcViewer and LcSignalFinder.
LcRe-porter creates an Excel report for the signals recordedby LcViewer. The software system was primarily developed by A.S. over nine years starting in 2011. J. H. contributedthe BLS (Box-Fitting Least Squares) (Kov´acs et al.2002) module derived from VARTOOLS (Hartman &Bakos 2016) for automatically finding periodic signalsin lightcurves. D. K. contributed the underlying algo-rithms and design for detrending lightcurves and phasefolding signals.Although LcTools may be used by anyone, fromnovices to professionals, it is primarily intended for ad-vanced citizen scientists, students, and universities. TheLcTools community currently consists of 77 registeredusers worldwide. A recent survey of the publicationsposted on arXiv found 20 papers that either cited oracknowledged use of the product for investigating vari-ous astronomical phenomena (C¸ okluk et al. 2019; Gaidoset al. 2019; Rappaport et al. 2019a; Eisner et al. 2019;Rappaport et al. 2019b; Ansdell et al. 2019; Borkovitset al. 2019; Lee et al. 2019; Ol´ah et al. 2018; Rodriguezet al. 2018; Borkovits et al. 2018; Malavolta et al. 2018;LaCourse & Jacobs 2018; Rappaport et al. 2018; Zhouet al. 2018; Christiansen et al. 2018; Rappaport et al.2017; Schmitt et al. 2016; Ansdell et al. 2016; Kippinget al. 2015). https://arxiv.org/list/astro-ph.EP/recent a r X i v : . [ a s t r o - ph . I M ] O c t Schmitt, Hartman, and Kipping
This paper is organized as follows. Section 2 lists theprojects and HLSPs supported in LcTools. Section 3 de-scribes the data assets that can be used with the system.Section 4 covers LcGenerator while section 5 describesLcSignalFinder. Sections 6 and 7 cover LcViewer andLcReporter respectively. Section 8 provides a summaryand concluding remarks.See Appendix A for a list of hardware and softwarerequirements for running LcTools. SUPPORTED PROJECTS AND HLSPSLcTools currently supports three projects and threeHLSPs. Projects include: • TESS (Ricker et al. 2015) – • K2 (Howell et al. 2014) – Long and short cadencelightcurves for 330,000 stars observed from 2014-2018 spanning 19 campaigns. • Kepler (Koch et al. 2010) – Long and short ca-dence lightcurves for 200,000 stars observed from2009-2013 spanning 17 quarters.HLSPs include: • TASOC (Handberg & Lund 2019) – Long cadencelightcurves produced from TESS Full-Frame Im-ages (FFIs). • K2SFF (Vanderburg & Johnson 2014) – Correctedlong cadence K2 lightcurves spanning 19 cam-paigns. • EVEREST (Luger et al. 2018) – Corrected longand short cadence K2 lightcurves spanning 19campaigns.In addition, TESS FFI lightcurve files for sector 1 areavailable from Oelkers (Oelkers & Stassun 2018) as ob-tained from the TESS Full Frame Image Portal . DATA ASSETSFive types of data assets can be used with LcTools – lightcurve files, star list files, signal libraries, TTVlibraries, and stellar properties. A description of eachtype is provided below. https://filtergraph.com/tess ffi/sector-01 Lightcurve Files
A lightcurve file contains time series informationfor a star for use with LcSignalFinder and LcViewer.Lightcurve files can be built using LcGenerator orLcViewer from the data archived at MAST (the Mikul-ski Archive for Space Telescopes). Lightcurve files canalso be downloaded directly from the LcTools website .Lightcurve directories on the LcTools website are avail-able by sector for TESS, by campaign for K2SFF, andby batch for Kepler.3.2. Star List Files
A star list file contains a list of stars observed in aspecific time period or batch. Time periods are projectspecific – sectors for TESS and campaigns for K2. Astar list file can be downloaded from the LcTools websiteand fed to LcGenerator for building a custom lightcurvedirectory. Multi-period star lists can also be downloadedfrom the website.3.3. Signal Libraries
A signal library is a set of signals that can be importedby LcSignalFinder and LcViewer when a lightcurve fileis loaded. Signal libraries may be project, public, orprivate.A project signal library contains planet candidate sig-nals defined by the project. Libraries include: • TOIs – TESS Objects of Interest obtained fromExoFOP-TESS . • CTOIs – Community TESS Objects of Interest ob-tained from ExoFOP-TESS. • K2OIs – K2 Objects of Interest obtained fromNEA (the NASA Exoplanet Archive). • KOIs – Kepler Objects of Interest obtained fromNEA. • TCEs – Threshold Crossing Events obtained fromMAST for TESS and from NEA for Kepler.A public signal library contains signals that were cre-ated with LcViewer for use by a group of individuals aspart of a team collaboration. The signals are located ina shared Google Drive folder.A private signal library contains signals that were cre-ated with LcViewer for personal use only. The signals https://archive.stsci.edu/ https://sites.google.com/a/lctools.net/lctools/data-sources https://exofop.ipac.caltech.edu/tess/ https://exoplanetarchive.ipac.caltech.edu/ cTools TTV Libraries
A TTV library contains information for aligning pe-riodic signals in a lightcurve that have been shifted dueto transit timing variations. A library can be importedby LcSignalFinder and LcViewer when a lightcurve fileis loaded. TTV libraries may be public or private. Useof TTV libraries is optional.Currently, there are two public TTV libraries availablein shared Google Drive folders. Both are for the Keplerproject. They include: • TTVs Kepler Mazeh – A TTV library derivedfrom the Holczer and Mazeh catalog (Holczer et al.2016). • TTVs Kepler Schmitt – A supplemental TTV li-brary manually created with LcViewer by the leadauthor for use with TTVs Kepler Mazeh.3.5.
Stellar Properties
Stellar properties may be imported from MAST orNEA by LcSignalFinder and LcViewer when a lightcurvefile is loaded. Properties include the star ID, stellarmagnitude, temperature, mass, radius, and distance tothe star. LcGenerator
LcGenerator builds lightcurve files in bulk for use withLcSignalFinder and LcViewer. For example, LcGenera-tor can be used to build lightcurve files for all the CTLstars in a TESS sector typically consisting of 20,000stars.The main application window for LcGenerator isshown in Figure 1. The window can be moved any-where on the screen. The position will be rememberedthe next time the application is started. The windowcan also be minimized so that the application runs inthe background out of the way.4.1.
Setting Up a Job
Main job settings in the application window include: • The target lightcurve directory. • The LcTools project name. Available projectnames include TESS, TESS TASOC, K2,K2 EVEREST, K2 SFF, and Kepler. • The star list file for lightcurve files to build. Typi-cally, a star list file is downloaded from the LcToolswebsite. • The time series periods to include in the build.Periods are project specific – sectors for TESS,campaigns for K2, and quarters for Kepler. • The desired cadence type – long or short. Forshort cadence data, the bin size must also be spec-ified in data points per hour (PPH). Available binsizes include 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30PPH for TESS related projects and 2, 3, 4, 5, 6,10, 12, 15, 20, 30, and 60 PPH for K2 and Keplerrelated projects. • The flux type – PDCSAP for the de-trended/corrected data and SAP for theraw/uncorrected data. • The quality filter for removing low quality datapoints from the generated lightcurves. If radiobutton 1 is selected, no data points will be re-moved. If button 2 is selected, all data points hav-ing flagged quality bits will be removed. If button3 is selected, all data points having flagged qual-ity bits will be removed except a selected list ofquality bits to ignore.4.2.
Executing a Job
To begin a job, the “Start Job” button must beclicked. At any point thereafter, the job can be pausedand resumed by clicking the associated on-screen but-tons (not shown). Progress of the job can be monitoredvia the Job Status box located in the bottom left cornerof the window.4.3.
The Build Process for a Lightcurve File
For each lightcurve file to build, LcGenerator performsthe following tasks subject to the job settings: 1) Down-loads the applicable time series files from MAST, 2) con-verts the time series files from FITS to text, 3) filtersout low quality data points, 4) for short cadence data,bins the data points to the specified data rate, 5) nor-malizes the flux values to a mean value of 1.0, 6) mergesthe normalized time series data together, and 7) writesthe resulting file into the lightcurve directory.4.4.
Supporting Documentation
A user guide for LcGenerator can be accessed fromthe menu bar. The document can also be accessed fromthe LcTools installation directory. LcSignalFinder
LcSignalFinder uses the BLS algorithm to detect andrecord periodic signals found in a large set of lightcurvefiles for subsequent use with LcViewer. For example,
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Figure 1.
The LcGenerator Window.
LcSignalFinder can be used to detect and record all theperiodic signals found in the CTL lightcurve files for aTESS sector typically consisting of 20,000 files. Detec-tion of both periodic dips and periodic peaks is sup-ported.The main application window for LcSignalFinder isshown in Figure 2. The window can be moved anywhereon the screen. The position will be remembered thenext time the application is started. The window canalso be minimized so that the application runs in thebackground out of the way.5.1.
Setting Up a Job
Main Job Settings
Main job settings in the application window include: • The lightcurve directory in which to search for pe-riodic signals. Typically, this directory is eitherdownloaded from the LcTools website or built withLcGenerator. • The list of lightcurve files to process in the direc-tory. By default, all files are selected. Individualfiles can be selected or deselected with the mouse.The “Filter” button selects files on the basis ofa specified search pattern. For example, “*PD-CSAP*” selects all files with “PDCSAP” in thefilename.The “From Build List” button selects all files thatwere last built with LcGenerator.The “From Star List” button selects all files whoseleading star IDs match the star IDs found in aspecified star list file. • The lightcurve preparation options. Checkboxesare available for removing high data point outliers,removing low data point outliers, and for detrend-ing the lightcurves. Normally, all three boxes arechecked. • BLS filters for signals to find and return. Filtersinclude 1) min. signal-to-noise ratio, 2) min. num-ber of instances per periodic signal, 3) max. num- cTools Figure 2.
The LcSignalFinder Window ber of signals per lightcurve, 4) min. and max.signal size in REarth units, 5) min. and max. pe-riod in days, and 6) min. and max. signal durationin hours. • The target signal direction – Down for dips andUp for peaks. • The type(s) of dipping signals to find. Seven typesare available:1. EB – Eclipsing binary signals.2. EB-P – Primary eclipse signals for EBs.3. EB-S – Secondary eclipse signals for EBs.4. PC – Planet candidate signals.5. PC-Troj – Host planet signals for trojans.6. Troj – Trojan signals.7. Other – All other periodic signals. 5.1.2.
Signal Libraries
Signal libraries for the job can be set up using thedialog box shown in Figure 3.At minimum, the library list will contain all availableproject libraries for the base project – TOIs, CTOIs, andTCEs for TESS, K2OIs for K2, and KOIs and TCEs forKepler. Optionally, there may be one or more public andprivate signal libraries in the list. Normally all availablesignal libraries are selected.In the example shown, there are five libraries in thelist all of which are selected for use. The first threeare project libraries. The last two are private libraries.Using the mouse, the user can select and deselect thedesired libraries as needed.The list is maintained in precedence order with thehighest priority library at the top and the lowest prioritylibrary at the bottom. Items in the list can be reorderedusing the “Up” and “Down” buttons.
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Figure 3.
The “Setup Signal Libraries” Dialog Box
Public and private libraries can be added to the listor removed from the list via the associated buttons.Project libraries cannot be added or removed.5.1.3.
TTV Libraries
TTV libraries for the job can be set up using a di-alog box similar to the one for signal libraries. Publicand private libraries can selected, deselected, reordered,added, and removed from the list as needed.5.1.4.
Stellar Properties
Stellar properties for the job can be enabled or dis-abled using the dialog box shown in Figure 4. Normally,stellar properties are enabled.
Figure 4.
The “Setup Project Resources” Dialog Box
Executing a Job
To begin a job, the “Start Job” button must beclicked. At any point thereafter, the job can be paused and resumed by clicking the associated on-screen but-tons (not shown). Progress of the job can be monitoredvia the Job Status box located in the bottom right cor-ner of the window.5.3.
The Signal Detection Process for a Lightcurve File
For each selected lightcurve file, LcSignalFinder per-forms the following tasks subject to the job settings:1. Reads the lightcurve file into memory.2. Imports the stellar properties for the host starfrom MAST or NEA.3. Imports the signals for the lightcurve from the se-lected signal libraries in precedence order and theninstantiates them in the lightcurve.4. Imports the TTV records for the signals from theselected TTV libraries in precedence order andthen aligns the instances of the signals in thelightcurve based on the offset information.5. Removes the data points for all instantiated sig-nals in the lightcurve so that BLS will not findand return known signals.6. Removes the worst 1% of high outliers and theworst 0.05% of low outliers from the lightcurve.7. Detrends the lightcurve using a moderately aggres-sive moving median curve fit.8. If the target signal direction is Up, inverts the datapoints in the lightcurve so that peaks become dipsenabling BLS to detect them.9. Executes BLS repeatedly to find all periodic sig-nals in the lightcurve. Processing stops when themaximum number of signals is reached per the jobsettings or no more signals are found.10. Analyzes the signals found. If the target signaldirection is Down, classifies each signal as follows: • If the signal size is greater than 30 REarths orthe signal depth is greater than 50,000 ppmif the stellar radius is unknown, the signal isclassified as an EB. Otherwise it is classifiedas a PC. • If two PC signals have nearly identical peri-ods and have reference epochs that differ byapproximately 1/6th of a period (correspond-ing to the L4 and L5 Lagrange points), thedeeper PC signal is re-classified as a PC-Trojand the shallower PC signal is re-classified asa Troj. cTools • If two EB or PC signals have nearly identicalperiods, the deeper signal is re-classified asan EB-P (primary eclipse) and the shallowersignal is re-classified as an EB-S (secondaryeclipse). • If the signal duration is greater than 0.2 timesthe signal period, the signal is classified asOther. Such signals are not likely to be plan-ets or EBs.The classification method described above onlyserves as an initial approximation based on pre-liminary information. Results should not be re-garded as absolute. Vetting of the signals will berequired before a more accurate classification canbe determined.11. Records all periodic signals that match the job set-tings in the LcSignalFinder window.5.4.
Vetting the Signals
Vetting of the periodic signals recorded by LcSig-nalFinder is handled in LcViewer as described in sec-tion 6.13. Both LcSignalFinder and LcViewer can berun concurrently to expedite the processing of signals ina lightcurve directory.5.5.
Supporting Documentation
A user guide for LcSignalFinder can be accessed fromthe menu bar. The document can also be accessed fromthe LcTools installation directory. LcViewer
LcViewer is a multipurpose graphics application forfinding and recording signals of interest in lightcurves.Via the application, a user is able to 1) build, view,edit, and detrend lightcurves, 2) detect, record, measure,track, locate, query, display, and phase fold signals, 3)record TTVs, 4) show background flux, 5) measure timeand flux intervals, and 6) query stellar properties.See Figure 30 for available menu bar commands andFigure 31 for available hot keys and hot buttons. Al-though many operations in LcViewer may be performedusing either technique, for brevity only hot keys and hotbuttons will be mentioned in this document.In the discussion that follows, M1 refers to the leftmouse button and M2 to the right mouse button.6.1.
Setting Up the Environment
Signal libraries, TTV libraries, and stellar propertiesfor LcViewer can be set up in a manner similar to LcSig-nalFinder. See sections 5.1.2, 5.1.3, and 5.1.4 respec-tively. 6.2.
Opening Lightcurve Files
Lightcurve files can be opened in two ways – via awork group for opening a large set of files sequentiallyand through a dialog box for opening files individually.6.2.1. Opening Lightcurve Files Through a Work Group
A work group is a set of lightcurve files to open se-quentially at the click of a button or press of a key forrapidly iterating though a large list of files. For example,a work group could be set up for viewing all the CTLlightcurve files for a TESS sector typically consisting of20,000 files.A work group can be set up by clicking the “Setup”button located in the lower left corner of the LcViewerwindow (see Figure 8) or by pressing the Shift+w key.The “Setup Work Group” dialog box will then be openedas shown in Figure 5.By default, all the files in a specified lightcurve direc-tory are selected for use. Individual items in the list canbe selected or deselected using the mouse.
Figure 5.
The “Setup Work Group” Dialog Box
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Clicking the “Filter” button selects files on the basis ofa specified search pattern. For example, “*PDCSAP*”selects all files with “PDCSAP” in the filename.Clicking the “From Build List” button selects all filesthat were last built with LcGenerator.Clicking the “From Signals Found” button selects allfiles in which periodic signals were found by LcSig-nalFinder. This step is required as part of the signalvetting process as described in section 6.13. Files withsignals that have already been dispositioned (created ordeleted) as part of the vetting process are excluded fromthe selected list.Once a work group has been set up, the files can beopened sequentially (forward or backward) by clickingthe “Next” or “Prev” button located in the lower leftcorner of the LcViewer window (see Figure 8) or bypressing the equivalent Shift+n or Shift+p key.The loading process for a lightcurve file is describedin section 6.2.3.6.2.2.
Opening Lightcurve Files Through a Dialog Box
A lightcurve file can be opened individually by press-ing the Shift+f key or by selecting the equivalent com-mand from the menu bar. The “Open Lightcurve” di-alog box will then be displayed as shown in Figure 6.Upon selecting the target lightcurve directory and hoststar ID, the method for opening the file must be selected.Two options are available – generate a new file in thedirectory or open an existing file from the directory. Figure 6.
The “Open Lightcurve” Dialog Box
If the first option is selected, the “Time Series Selec-tion” dialog box will be opened for specifying the buildoptions as shown in Figure 7. The build options andbuild process for a lightcurve file are similar to thosedescribed for LcGenerator and so will not be repeatedhere. See sections 4.1 and 4.3 respectively.
Figure 7.
The “Time Series Selection” Dialog Box
The Load Process for a Lightcurve File
Once a lightcurve file is ready to be opened, LcViewerperforms the following tasks subject to the environmentsettings:1. Reads the file into memory.2. Imports the stellar properties for the host starfrom MAST or NEA.3. Imports the signals for the lightcurve from the se-lected signal libraries in precedence order and theninstantiates them in the lightcurve.4. Imports the TTV records for the signals from theselected TTV libraries in precedence order andthen aligns the instances of the signals in thelightcurve based on the offset information.5. Displays the lightcurve in the main LcViewer win-dow. cTools
The LcViewer Window
The main LcViewer window is shown in Figure 8. Thewindow can be resized and repositioned anywhere on thescreen. The size and position will be remembered thenext time the application is started. The window canbe maximized to fill the screen or minimized so that itruns in the background out of the way.Major components in the window include: • The Local View Window showing the working areaof the lightcurve. Time is displayed along the x-axis and normalized flux along the y-axis. • The Global View Window showing the fulllightcurve. • The Current View Rectangle showing where thelocal view is located relative to the full lightcurve. • The Horizontal Scroll Bar for panning thelightcurve left and right. • The Vertical Scroll Bar for panning the lightcurveup and down. • The Load Work Group Control for setting up andloading lightcurve files from a work group. Seesection 6.2.1. • The Locate Signal Control for finding and display-ing signals in the lightcurve. • The Zoom View Control for zooming in or out ofthe lightcurve. • The Save/Restore View Control for saving andrestoring a view or to quickly return to the pre-vious view if it was accidentally changed.6.4.
Lightcurve Display
Optimizing the Initial View
When a lightcurve is initially displayed, the view isscaled and shifted vertically such that high data pointoutliers are clipped. This optimization feature preventsexcessive vertical shrinkage due to extreme outliers.6.4.2.
Scaling of Data Points
The lightcurve is normally drawn using white mediumsize data points connected with lines. However, if thedata points are too close together, the application em-ploys a congestion mitigation strategy whereby the datapoints are drawn in a smaller size and not connectedwith lines. This behavior can be be overridden usingthe Shift+z key which forces medium size points andconnected lines. 6.4.3.
Rendering of Signals
Imported signals from a signal library are highlightedin color. To help differentiate signals visually, each oneis assigned a different color when the lightcurve file isloaded. All the instances of a periodic signal are drawnin the same color.Signals are drawn by level number. All level 1 sig-nals are drawn first followed by all level 2 signals. Thisensures that level 2 signals are on top and visible.A level 1 signal is a primary signal such as an planetarytransit. A level 2 signal is a secondary signal of theprimary signal such as an exomoon transit. The levelnumber is set when the signal is created. See section6.8.1 for details.If two signals with the same level number overlap, theintersecting region will be highlighted in red. See Figure9 for an example.A partially or fully buried signal can be made fullyvisible by pressing the Ctrl+r key.6.4.4.
Displaying Signal Markers
Left and right vertical markers can be displayed inred around each instance of the current signal in thelightcurve for visual reference purposes. See Figure 10for an example. The time span between the left andright markers can specified in terms of signal durations,hours, days, periods, and Hill time scale.6.4.5.
Displaying Background Flux
Background flux can be displayed using the Shift+bkey to help identify light-scattering events in thelightcurve. See Figure 11 for an example. Currently,this feature is only available for TESS and TASOClightcurves. 6.5.
Lightcurve Navigation
Selecting a View
A view may be selected in the Local or GlobalView Window by selecting a rectangular section of thelightcurve using the M1 button.6.5.2.
Panning a Lightcurve
A lightcurve can be panned in three ways: 1) By usingthe horizontal and vertical scroll bars, 2) by grabbingthe local view with the M2 button and then draggingthe view in the desired direction, and 3) by grabbingthe Current View Rectangle with the M2 button andthen dragging the rectangle in the desired direction.6.5.3.
Auto-Scrolling a Lightcurve
Auto-scrolling a lightcurve is a way to automaticallypan the lightcurve in association with an operation that0
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Figure 8.
The LcViewer Window
Figure 9.
Two overlapping planetary transit signals. Thered area indicates the intersecting region. requires a starting and ending location be selected withthe mouse. If the ending location for the operation fallsoutside the current view, the view can be automaticallyscrolled by moving the cursor outside the Local ViewWindow while the main operation key is held down.This is equivalent to panning the lightcurve with a scrollbar. The scroll speed is governed by the distance be-
Figure 10.
Reference markers in red drawn around eachinstance of a signal using a time span of 7 signal durations. tween the window boundary and the cursor. The greaterthe distance, the faster the scroll speed.6.5.4.
Zooming In or Out of a Lightcurve
A lightcurve can be zoomed in or out in three mainways: 1) By using the four horizontal and vertical zoombuttons in the Zoom View Control, 2) by using thefour arrow keys on the keyboard, and 3) by pressingthe Ctrl+M2 button and then moving the cursor in thedirection to zoom. Of the three methods, the last one cTools Figure 11.
Background flux shown in red. The invertedred signal above the white candidate signal indicates thatthe white signal was caused by a light-scattering event. is the fastest and most versatile providing 360 degreezoom capability in one operation.The “Reset” button can be clicked to reset the viewto the optimized initial view. Typically, this is the fulllightcurve.As yet another way to zoom, the M1 button can bedouble-clicked inside the Local or Global View Win-dow to zoom in on a selected location or signal in thelightcurve.6.5.5.
Navigating the Instances of a Signal
The instances of a defined signal in a lightcurve can benavigated sequentially using the Locate Signal Control.Each time the “Next” or “Prev” button is clicked, thenext or previous instance of the selected signal is cen-tered in the Local View Window and zoomed in. Thehorizontal and vertical scaling factor is preserved be-tween instances.6.6.
Real-Time Tracking
The time, flux, and signal at the cursor can be moni-tored in real-time via the Tracking Information Box. SeeFigure 12 for an example.If the cursor is positioned over a data point, the datapoint will be enlarged to indicate that the time and fluxvalues have been snapped to the actual values in thelightcurve within six decimal places.6.7.
Measuring the Interval Between Two Locations
The time and flux interval between any two locationsin the Local View Window can be measured using theShift+M1 key.Pressing the key and then moving the mouse draws ameasurement line between the starting and ending loca-tion. If the ending location lies outside the Local ViewWindow, the lightcurve will be automatically scrolled asdescribed in section 6.5.3.
Figure 12.
The Tracking Information Box showing thetime, flux, and signal at the cursor.
The line is accompanied by a Measurement Informa-tion Box showing the time and flux interval betweenlocations. The time interval is given in days and hours.The flux interval is given in flux units, depth (ppm), andREarth units. An example of a time based measurementis shown in Figure 13 and a flux based measurement inFigure 14.
Figure 13.
A time based measurement. Here, the durationof a candidate signal is being measured.
Recording Signals
A signal may be recorded for any dip, peak, artifactor anomaly found in a lightcurve. There are no restric-tions as what a signal can represent other than it mustencompass at least three data points in the lightcurveincluding the end points. Signals may be periodic ornon-periodic.2
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Figure 14.
A flux based measurement. Here, the depth andsize of a candidate signal is being measured.
Creating a Signal
There are three ways to create a signal in LcViewer:1) By enclosing the relevant data points with a bound-ing box using the Ctrl+M1 button, 2) by clicking the“Create” button in the “Find Periodic Signals” dialogbox (see Figure 18), and 3) by clicking the “Create Sig-nal” button in the “Measure Candidate Signal” dialogbox (see Figures 27, 28, and 22).The “Create Signal” dialog box will then open asshown in Figure 15. The fields may or may not be filledin with default values depending on the method used tostart the process. At minimum, default values will bepopulated in the group boxes for Output Signal Libraryand Signal Times. The following fields can be set:
Figure 15.
The “Create Signal” dialog box. • Signal ID: An optional ID for the signal. Normally,this field is left blank. • Signal Type: The type of signal to create. A valuecan be selected from the drop-down list for an ex-isting type or entered into the field for a new type.At minimum, the drop-down list will contain types“PlanetaryTransit” and “EB”. • Signal Level: The level number for the signal – • Assoc Object: The ID of an object that is asso-ciated with the signal. A value can be selectedfrom the drop-down list for an existing ID or en-tered into the field for a new ID. At minimum,the drop-down list will contain two items – thehost star ID and a unique object ID of the form“ StarID.ObjectNum ”. For example, 38846515.01.An associated object is regarded as the source orcause for the signal based on the signal type. Forexample, if the signal type is PlanetaryTransit,the associated object would be the ID of the hostplanet. • Library Type: The type of signal library in whichto store the signal. Options include “Private:Inside Lightcurve Directory”, “Private: OutsideLightcurve Directory”, and “Public”. Normally,the first option is used. • Library Path: The full path name of the targetsignal library. • Period: If the signal is periodic, the time intervalin days between each instance of the signal. If thesignal is non-periodic, a value of 0.Non-periodic signals can be created with multiple in-stances by setting the signal type and associated ob-ject to the same value in each instance. LcViewer thengroups all the instances together under one parent sig-nal.Once the dialog box is filled in and submitted, thesignal will be added to the target signal library, instan-tiated in the lightcurve, and highlighted.6.8.2.
Editing a Signal
A public or private signal may be edited by moving thecursor over the signal and then pressing the Ctrl+e key.A bounding box for the signal will be drawn enabling theleft and right sides to be adjusted with the mouse. Afterthe sides are adjusted, a dialog box similar to Figure 15will be opened enabling the field values to be edited. cTools
Deleting a Signal
A defined signal or instance thereof may be deletedby moving the cursor over the signal and pressing theCtrl+d key. 6.8.4.
Moving a Signal
A defined signal or instance thereof may be movedby positioning the cursor over the signal, pressing them+M2 button, and then dragging the bounding box forthe signal to the target location using the mouse.6.9.
Recording TTVs
A TTV can be recorded for an instance of a de-fined periodic signal by moving, creating, or deletingthe instance in the lightcurve as described in sections6.8.4, 6.8.1, and 6.8.3 respectively. LcViewer interpretsa move, create, or delete operation for an instance of aperiodic signal as a TTV alignment request and recordsthe information in a TTV library rather than in theparent signal library.6.10.
Querying the Properties of a Defined Signal
The properties of a defined signal in a lightcurve canbe queried by moving the cursor over the signal andpressing the Ctrl+q key. The “Signal Properties” dialogbox will then open as shown in Figure 16.
Figure 16.
The “Signal Properties” dialog box.
Editing a Lightcurve
A section of a lightcurve can be removed by markingthe target section with a rectangle using the Alt+M2button. All data points inside the rectangle will bedeleted from the lightcurve. This feature is commonlyused to remove low quality sections of a lightcurve priorto manual detrending (see section 6.12).The edited lightcurve can optionally be saved to thesame lightcurve file or a different one.6.12.
Manually Detrending a Lightcurve
A lightcurve can be manually detrended to reducelarge-scale fluctuations so that signals are easier to de-tect.The detrending process is started by pressing theShift+d key or by selecting the equivalent commandfrom the menu bar. An initial green trend line willbe displayed in the lightcurve accompanied by the “De-trend Lightcurve” dialog box for controlling the opera-tion. See Figure 24 for an example. The dialog box canbe moved outside the LcViewer window so that it doesnot interfere with the lightcurve. The position will beremembered the next time the dialog box is opened.At this point the user may perform any of the opera-tions below: • Adjust the checkboxes for removing high and lowsingle point outliers from the lightcurve prior todetrending. If the first box is checked, the worst1% of high outliers are removed. If the secondbox is checked, the worst 0.05% of low outliers areremoved. Normally, both boxes are checked. • Select a trend line fitting method – Moving Me-dian or Spline. Moving Median is the default.Spline is not recommended for time spans over 100days. • Adjust the trend line fitting level. Levels rangefrom 1 to 25. The higher the value, the tighterthe fit and the flatter the lightcurve will be afterdetrending. The default value is 16.While adjusting the level, the green trend line canbe visually inspected for underfitting and overfit-ting. Overfitting may severely attenuate or de-stroy signals of interest when the lightcurve is de-trended. See Figure 17 for an example. • Click the “Detrend” button to detrend thelightcurve based on the fitted green line. See Fig-ure 25 for an example. • Click the “Redo” button to reset the lightcurve toits previous state so that the detrending operationcan be retried with different settings.4
Schmitt, Hartman, and Kipping
Figure 17.
Example of overfitting. The green trend lineextends well into the white signal which will cause the signalto be severely attenuated when the lightcurve is detrended. • Click the “OK” button to accept the detrendedresults. • Optionally save the detrended lightcurve to thesame lightcurve file or a different one.6.13.
Vetting Signals Found by LcSignalFinder
If periodic signals were found previously by LcSig-nalFinder, the signals must be vetted and then recordedin a signal library before they can be used.To start the process, a work group must first be setup for the lightcurves files having periodic signals fromLcSignalFinder. This can be done by clicking the “FromSignals Found” button in the “Setup Work Group” di-alog box as shown in Figure 5.Each file from the work group can then be openedsequentially by clicking the “Next” button at the bottomleft corner of the LcViewer window or by pressing theShift+n key.Upon opening a file, LcViewer will display the “FindPeriodic Signals” dialog box for controlling the vettingoperation. See Figure 18 for an example. The dialog boxcan be moved outside the LcViewer window so that itdoes not interfere with the lightcurve. The position willbe remembered the next time the dialog box is opened.Each signal in the dialog box will show the referenceepoch, signal duration in hours, period in days, signal-to-noise ratio (SNR), signal size in REarth units, typeof signal, and current disposition.At this point the user can perform the following oper-ations on each signal in the dialog box: • Select a working signal from the list. Each instanceof the signal will be marked with a green rectanglein the lightcurve for identification purposes. • Using the four navigation buttons in the dialogbox, iterate through each instance of the workingsignal to visually check the alignment between thegreen rectangle and the actual instance. • If the instances are misaligned, use the m+M2 but-ton to manually align the first or last instance inthe lightcurve whichever one has the greatest devi-ation. This will automatically adjust the referenceepoch and period resulting in a better overall fit. • Click the “Phase Fold” button to phase fold theperiodic signal and adjust the signal duration. Seesection 6.15 for more information. • If the signal is viable, click the “Create” buttonto record the signal in a library. The “Create Sig-nal” dialog box will then open with all the requiredfields filled in (see Figure 15). Upon clicking the“OK” button, the signal will be added to the tar-get signal library, instantiated in the lightcurve,and highlighted.If the signal is not viable, click the “Delete” buttonto delete the candidate signal from the dialog boxand lightcurve.6.14.
Detecting and Recording Periodic Signals
There are three methods in LcViewer for detecting andrecording periodic signals in a lightcurve – automatic,semi-automatic, and manual. Each method is describedbelow.6.14.1. Method 1: Automatic Signal Detection
In method 1, the current lightcurve is searched for pe-riodic signals using BLS in a manner similar to LcSig-nalFinder.The process is started by pressing the Ctrl+s key. The“Find Periodic Signals - Setup” dialog box will thenopen as shown in Figure 19. The settings in the di-alog box are identical to the ones for LcSignalFinder.See section 5.1.1 for details.LcViewer will then search for the first periodic sig-nal in the lightcurve using a process similar to that de-scribed in steps 5-10 of section 5.3. If a signal is found,the “Find Periodic Signals” dialog box will be openedand the instances of the signal marked with green rect-angles like that shown in Figure 18.The user can then examine each instance, adjust thereference epoch and period, phase fold the signal to ad-just the signal duration, and then record the signal ina library (if viable) as described in section 6.13. The“Find Another” button can then be clicked to search cTools Figure 18.
A lightcurve showing a periodic signal to be vetted in green accompanied by the “Find Periodic Signals” dialogbox for controlling the operation. Schmitt, Hartman, and Kipping
Figure 19.
The “Find Periodic Signals - Setup” dialog box. for the next periodic signal in the lightcurve. The pro-cess is repeated until all the periodic signals have beenfound and dispositioned.6.14.2.
Method 2: Semi-Automatic Signal Detection
In method 2, the user identifies a candidate referencesignal in the lightcurve. Using the reference signal as atemplate, LcViewer then searches the lightcurve for allmatching signals that are periodic with respect to thereference signal and returns the periods found.The process is started by enclosing the reference sig-nal with a rectangle using the Alt+M1 button. The“Measure Candidate Signal” dialog box will then openas shown in Figure 26. The dialog box can be moved out-side the LcViewer window so that it does not interferewith the lightcurve. The position will be rememberedthe next time the dialog box is opened.Upon clicking the “Check Periodicity” button in thedialog box, LcViewer scans the lightcurve for all signalsthat closely match the reference signal in terms of signalduration and depth. Next, it examines the signals foundto determine whether any are periodic with respect tothe reference signal. If found, the candidate periods arelisted in the dialog box with the strongest periods at thetop based on the matching signal count and percentage.See Figure 27 for an example.At this point the user can perform the following oper-ations on the candidate periods: • Select a working period from the list. Each in-stance of the signal at the selected period will thenbe marked with a rectangle in the lightcurve – green if the instance matches the reference signaland red if not. • Using the five navigation buttons in the dialogbox, iterate through each instance of the workingsignal to visually check the alignment between therectangle and the actual instance. • If the instances are misaligned, use the m+M2 but-ton to manually align the first or last instance inthe lightcurve whichever one has the greatest devi-ation. This will automatically adjust the referenceepoch and period resulting in a better overall fit. • Click the “Phase Fold” button to phase fold theworking signal. See section 6.15 for more informa-tion. • If the periodic signal is viable, click the “Create”button. The “Create Signal” dialog box will thenopen with all the required fields filled in (see Fig-ure 15). Upon clicking the “OK” button, the sig-nal will be added to the target signal library, in-stantiated in the lightcurve, and highlighted.6.14.3.
Method 3: Manual Signal Detection
In method 3, the user identifies two adjacent referencesignals in the lightcurve. Based on the time intervalbetween reference signals, LcViewer calculates a periodand then instantiates the signal across the lightcurve forthe period.The process is started by enclosing the first referencesignal with a rectangle using the Alt+M1 button. Thebest results are achieved if the reference signal residesnear the middle of the lightcurve. The “Measure Can-didate Signal” dialog box will then open as shown inFigure 26.The second reference signal is then enclosed with arectangle using Alt+M1. The second signal must beadjacent to the first signal, either before it or after itwith no intervening gaps. LcViewer then determinesthe period for the signal by calculating the time intervalbetween the two reference signals. Based on the period,LcViewer generates an entry in the list box, instantiatesthe signal in the lightcurve, and marks each instance ofthe signal with a yellow rectangle. See Figure 28 for anexample.The user can then examine each instance, adjust thereference epoch and period, phase fold the signal, andthen record the signal in a library (if viable) as describedin section 6.14.2. cTools
Phase Folding a Periodic Signal
A periodic signal may be phase folded to obtain a com-posite signal for study. There are three ways in whichto start the operation: 1) By pressing the Ctrl+f key in-side an instance of the signal, 2) by clicking the “PhaseFold” button inside the “Find Periodic Signals” dialogbox (see Figure 18), and 3) by clicking the “Phase FoldSignal” button inside the “Measure Candidate Signal”dialog box (see Figures 27 and 28).6.15.1.
The “Phase Fold Setup” Dialog Box
Upon starting the operation, the “Phase Fold Setup”dialog box will be opened as shown in Figure 20. Set-tings include:
Figure 20.
The “Phase Fold Setup” dialog box. • The signal region timescale indicating the timespan to be phase folded for each instance of theperiodic signal in the lightcurve centered at themidpoint of the instance.The timescale is governed by two parameters – time units and time value. Available time unitsinclude hours, days, periods, signal durations, Hilltimescale, and minimum required time (the de-fault). The time value indicates the number ofunits in the signal region. For example, 7 signaldurations. • Filtering options for removing high data point out-liers, low data point outliers, and overlapping sig-nals from the lightcurve prior to detrending. Nor-mally all three options are selected. • Detrending options for setting the trend line fittingmethod and flattening level.Two fitting methods are available – Polynomialand Spline. The default is Polynomial for signalregions under 10 days and Spline for signal regionsabove 10 days.Flattening levels range from 1 to 25. The higherthe value, the tighter the fit and the flatter thesignal region will be after detrending. The defaultis 1 (no flattening). • An option for showing the detrending stages oneach instance of the signal to check for underfit-ting and overfitting. Normally, this option is notselected. • The bin size in minutes for binning the phasefolded data points. Available sizes include 1, 2,3, 4, 5, 6, 10, 12, 15, 20, and 30 minutes. Thedefault is 10 minutes.For a typical user, using the default values will providehigh quality phase folded results. No adjustments arenormally needed.6.15.2.
The Phase Folding Process
Once the dialog box is submitted, LcViewer will per-form the following tasks subject to the settings:1. Removes the worst 1% of high outliers and theworst 0.05% of low outliers from the lightcurve.2. Removes the data points for all overlapping sig-nals in the lightcurve to prevent the signals fromappearing in the phase folded lightcurve.3. For each instance of the target signal in thelightcurve, a) fits a trend line through the sig-nal region excluding the instance itself which ismasked out, b) detrends the signal region basedon the fitted trend line, c) normalizes the flux val-ues in the signal region to a mean value of 1.0, d)checks the quality of the detrended result and re-jects the instance if the quality is low, and e) addsthe normalized data points from the signal regionto a collection area.4. Bins the data points from the collection area.8
Schmitt, Hartman, and Kipping
5. Displays the phase folded lightcurve and an ac-companying dialog box for controlling the phasefold operation.6.15.3.
The Phase Folded Lightcurve
A sample phase folded lightcurve is shown in Figure21. The small grey dots represent the unbinned datapoints. The large green dots represent the binned datapoints. The green line shows the average fit through thebinned points.Time is displayed along the x-axis with the midpointof the phase folded signal located at time = 0. Basedon the signal region timescale, time units may be shownin hours, days, or periods. Normalized flux is displayedalong the y-axis.A horizontal reference line is drawn at a flux value of1.0. The left and right vertical reference lines representthe extent of the phase folded signal. The time spanbetween the lines is the signal duration.6.15.4.
The “Phase Folded Signal Control” Dialog Box
The accompanying dialog box shown in Figure 21 canbe used to fine-tune the original phase fold settings andto control how the lightcurve is displayed. The dia-log box can be moved outside the LcViewer window sothat it does not interfere with the lightcurve. The posi-tion will be remembered the next time the dialog box isopened.The Signal Region Timescale, Fitting Method, Flat-tening Level, and Bin Size were all described in section6.15.1 and so will not be repeated here. Additional set-tings include the following: • An option for folding the left side data points overthe right side to check for symmetry and to com-bine points. • The target method for averaging flux values whenbinning data points. Options include Mean andMedian. The default is Mean. • The type of data points to display in thelightcurve. Options include “Show Unbinned PtsOnly”, “Show Binned Pts Only”, and “Show Un-binned and Binned Pts”. The last option is thedefault. • The type of line or fitted curve to display throughthe binned data points. Options include “NoLines”, “Connect Pts With Lines”, and “Fit CurveBetween Pts”.For the last option, a spline curve is used for sig-nal regions below 10 days and a moving median curve is used for signal regions above 10 days.The Smoothing Level control adjusts the smooth-ing factor. Levels range from 1 to 33. The lowerthe value, the tighter the fit. The higher the value,the looser the fit. The default value is 17 whichprovides average smoothing. • An option for turning the reference lines on andoff.For a typical user, using the default values will providehigh quality phase folded results. No adjustments arenormally needed.6.15.5.
Adjusting the Signal Duration
The duration of the phase folded signal can be ad-justed by placing a bounding box around the signal usingthe Alt+M1 button. The “Measure Candidate Signal”dialog box will open as shown in Figure 22.Upon clicking the “Change Periodic Signal Duration”button in the dialog box, LcViewer will change the signalduration based on the bounding box and then adjust theleft and right vertical reference lines accordingly. Whenthe “Phase Folded Signal Control” dialog box is closed,the adjusted duration will be applied to the source signalthat was phase folded.6.15.6.
Auxiliary Operations
Most operations that can be performed in a regularlightcurve can be done in a phase folded lightcurve. Theuser can 1) save and load phase folded lightcurve files, 2)navigate the lightcurve (select views, pan, and zoom), 3)measure intervals, 4) measure, create, edit, delete, andmove signals, 5) query the properties of a defined signal,and 6) query the properties of the host star.6.16.
Querying the Stellar Properties for the Host Star
The stellar properties for the host star can be queriedfrom MAST or NEA by pressing the Shift+q key or byselecting the equivalent command from the menu bar.The “Stellar Properties” dialog box will then open asshown in Figure 23.6.17.
Supporting Documentation
A user guide and quick reference manual for LcViewercan be accessed via the Shift+g and Shift+m keys re-spectively or by selecting the equivalent commands fromthe menu bar. Both documents can also be accessedfrom the LcTools installation directory. cTools Figure 21.
A phase folded lightcurve and accompanying dialog box.7.
LcReporter
Main Features
LcReporter creates an Excel report for the signalsrecorded by LcViewer. The signals from multiple publicand private signal libraries may be combined togetherinto one report. Separate worksheets in the file are pro-vided for regular signals and phase folded signals.Data columns on the regular signals worksheet includestar ID, signal ID, signal type, associated object, signallevel, start time, end time, midpoint time, duration, pe-riod, and signal file. See Figure 29 for an example.Data columns on the phase folded signals worksheetinclude all those for regular signals (excluding the pe-riod) plus data columns for the periodic signal that wasphase folded. These include the source signal type, as-sociated object, first epoch, duration, and period.The signals in a worksheet can be sorted and filteredto help organize and analyze the data collected. 7.2.
Supporting Documentation
A user guide for LcReporter can be accessed from theLcTools installation directory. SUMMARYLcTools is a Windows based software system for find-ing and recording signals of interest in large sets oflightcurves for the TESS, K2, and Kepler projects inaddition to the TASOC, K2SFF, and EVEREST HighLevel Science Products.The system can be used to generate, view, edit, anddetrend lightcurves and to detect, record, measure, lo-cate, query, highlight, and phase fold signals. Signalscan be recorded for any type of phenomena or artifactwhether periodic or non-periodic. The system can alsobe used to record TTVs, measure time and flux intervals,query stellar properties, and generate signal reports.The software is free and can be obtained from thelead author by request at [email protected]. For0
Schmitt, Hartman, and Kipping
Figure 22.
The “Measure Candidate Signals” dialog boxfor a phase folded lightcurve.
Figure 23.
The “Stellar Properties” dialog box. additional information on the product, see the LcToolsProduct Description .APPENDIX A. RUN-TIME REQUIREMENTSThe following hardware and software is required to run LcTools: • Windows OS (XP, Vista, 7, 8, 10). • • •
100 GB free disk space. • • • High-speed Internet connection. • Microsoft Word. • Microsoft Excel (if using LcReporter). • Google Drive (if using public signal libraries or public TTV libraries). https://sites.google.com/a/lctools.net/lctools/lctools-product-description cTools Ansdell, M., Gaidos, E., Rappaport, S. A., et al. 2016, ApJ,816, 69, doi: 10.3847/0004-637X/816/2/69Ansdell, M., Gaidos, E., Jacobs, T. L., et al. 2019,MNRAS, 483, 3579, doi: 10.1093/mnras/sty3289Borkovits, T., Albrecht, S., Rappaport, S., et al. 2018,MNRAS, 478, 5135, doi: 10.1093/mnras/sty1386Borkovits, T., Rappaport, S., Kaye, T., et al. 2019,MNRAS, 483, 1934, doi: 10.1093/mnras/sty3157C¸ okluk, K. A., Ko¸cak, D., I¸cli, T., et al. 2019, MNRAS,488, 4520, doi: 10.1093/mnras/stz2051Christiansen, J. L., Crossfield, I. J. M., Barentsen, G., et al.2018, AJ, 155, 57, doi: 10.3847/1538-3881/aa9be0Eisner, N. L., Barrag´an, O., Aigrain, S., et al. 2019, arXive-prints, arXiv:1909.09094.https://arxiv.org/abs/1909.09094Gaidos, E., Jacobs, T., LaCourse, D., et al. 2019, MNRAS,488, 4465, doi: 10.1093/mnras/stz1942Handberg, R., & Lund, M. N. 2019,doi: 10.5281/zenodo.2579846Hartman, J. D., & Bakos, G. . 2016, Astronomy andComputing, 17, doi: 10.1016/j.ascom.2016.05.006Holczer, T., Mazeh, T., Nachmani, G., et al. 2016, TheAstrophysical Journal Supplement Series, 225,doi: 10.3847/0067-0049/225/1/9Howell, S. B., Sobeck, C., Haas, M., et al. 2014, TheAstronomical Society of the Pacific, 126,doi: 10.1086/676406Kipping, D. M., Schmitt, A. R., Huang, X., et al. 2015,ApJ, 813, 14, doi: 10.1088/0004-637X/813/1/14Koch, D. G., Borucki, W. J., Basri, G., et al. 2010, TheAstrophysical Journal Letters, 713,doi: 10.1088/2041-8205/713/2/L79Kov´acs, G., Zucker, S., & Mazeh, T. 2002, Astronomy andAstrophysics, 391, doi: 10.1051/0004-6361:20020802LaCourse, D. M., & Jacobs, T. L. 2018, Research Notes ofthe American Astronomical Society, 2, 28,doi: 10.3847/2515-5172/aaad61 Lee, J. W., Hong, K., & Kristiansen, M. H. 2019, AJ, 157,17, doi: 10.3847/1538-3881/aaf0fbLuger, R., Kruse, E., Foreman-Mackey, D., Agol, E., &Saunders, N. 2018, The Astronomical Journal, 156,doi: 10.3847/1538-3881/aad230Malavolta, L., Mayo, A. W., Louden, T., et al. 2018, AJ,155, 107, doi: 10.3847/1538-3881/aaa5b5Oelkers, R. J., & Stassun, K. G. 2018, The AstronomicalJournal, 156, 132, doi: 10.3847/1538-3881/aad68eOl´ah, K., Rappaport, S., Borkovits, T., et al. 2018, A&A,620, A189, doi: 10.1051/0004-6361/201834106Rappaport, S., Vanderburg, A., Borkovits, T., et al. 2017,MNRAS, 467, 2160, doi: 10.1093/mnras/stx143Rappaport, S., Vanderburg, A., Jacobs, T., et al. 2018,MNRAS, 474, 1453, doi: 10.1093/mnras/stx2735Rappaport, S., Vanderburg, A., Kristiansen, M. H., et al.2019a, MNRAS, 488, 2455, doi: 10.1093/mnras/stz1772Rappaport, S., Zhou, G., Vanderburg, A., et al. 2019b,MNRAS, 485, 2681, doi: 10.1093/mnras/stz537Ricker, G. R., Winn, J. N., Vanderspek, R., et al. 2015,Journal of Astronomical Telescopes, Instruments, andSystems, 1, doi: 10.1117/1.JATIS.1.1.014003Rodriguez, J. E., Becker, J. C., Eastman, J. D., et al. 2018,AJ, 156, 245, doi: 10.3847/1538-3881/aae530Schmitt, J. R., Tokovinin, A., Wang, J., et al. 2016, AJ,151, 159, doi: 10.3847/0004-6256/151/6/159Vanderburg, A., & Johnson, J. A. 2014, Publications of theAstronomical Society of the Pacific, 126,doi: 10.1086/678764Zhou, G., Rappaport, S., Nelson, L., et al. 2018, ApJ, 854,109, doi: 10.3847/1538-4357/aaa9b9 Schmitt, Hartman, and Kipping
Figure 24.
A lightcurve to be detrended accompanied by the “Detrend Lightcurve” dialog box. The green line is the fittedtrend line. See Figure 25 for the detrended result. cTools Figure 25.
The detrended result for the original lightcurve shown in Figure 24. Schmitt, Hartman, and Kipping
Figure 26.
A marked reference signal in yellow accompanied by the “Measure Candidate Signal” dialog box. Applicable tosignal detection methods 2 and 3. cTools Figure 27.
The “Measure Candidate Signal” dialog box showing one detected period for the reference signal. Each instanceof the periodic signal in the lightcurve is marked with a rectangle – green if it matches the reference signal and red if not.Applicable to signal detection method 2 only. Schmitt, Hartman, and Kipping
Figure 28.
The “Measure Candidate Signal” dialog box showing the period for the two adjacent reference signals. Eachinstance of the periodic signal in the lightcurve is marked with a yellow rectangle. Applicable to signal detection method 3 only.
Figure 29.
The Regular Signals worksheet produced by LcReporter. cTools Figure 30.
Menu bar commands in LcViewer Schmitt, Hartman, and Kipping