## Detalles de publicación

PP 021005

## A Modified Kwee─Van Woerden Method for Eclipse Minimum Timing with Reliable Error Estimates

IAC

The Kwee - van Woerden (KvW) method used for the determination of eclipse

minimum times has been a staple in eclipsing binary research for decades, due

its simplicity and the independence of external input parameters, which also

makes it well-suited to obtaining timings of exoplanet transits. However, its

estimates of the timing error have been known to have a low reliability. During

the analysis of very precise photometry of CM Draconis eclipses from TESS space

mission data, KvW's original equation for the timing error estimate produced

numerical errors, which evidenced a fundamental problem in this equation. This

contribution introduces an improved approach for calculating the timing error

with the KvW method. A code that implements this improved method, together with

several further updates of the original method, are presented. An example of

the application to CM Draconis light curves from TESS is given. The eclipse

minimum times are derived with the KvW method's three original light curve

folds, but also with five and seven folds. The use of five or more folds

produces minimum timings with a substantially better precision. The improved

method of error calculation delivers consistent timing errors which are in

excellent agreement with error estimates obtained by other means. In the case

of TESS data from CM Draconis, minimum times with an average precision of 1.1

seconds are obtained. Reliable timing errors are also a valuable indicator for

evaluating if a given scatter in an O-C diagram is caused by measurement errors

or by a physical period variation.

minimum times has been a staple in eclipsing binary research for decades, due

its simplicity and the independence of external input parameters, which also

makes it well-suited to obtaining timings of exoplanet transits. However, its

estimates of the timing error have been known to have a low reliability. During

the analysis of very precise photometry of CM Draconis eclipses from TESS space

mission data, KvW's original equation for the timing error estimate produced

numerical errors, which evidenced a fundamental problem in this equation. This

contribution introduces an improved approach for calculating the timing error

with the KvW method. A code that implements this improved method, together with

several further updates of the original method, are presented. An example of

the application to CM Draconis light curves from TESS is given. The eclipse

minimum times are derived with the KvW method's three original light curve

folds, but also with five and seven folds. The use of five or more folds

produces minimum timings with a substantially better precision. The improved

method of error calculation delivers consistent timing errors which are in

excellent agreement with error estimates obtained by other means. In the case

of TESS data from CM Draconis, minimum times with an average precision of 1.1

seconds are obtained. Reliable timing errors are also a valuable indicator for

evaluating if a given scatter in an O-C diagram is caused by measurement errors

or by a physical period variation.