A Robust Method to Measure Centroids of Spectral Lines

TL;DR

This paper introduces a simple quadratic fitting method to accurately measure spectral line centroids in astronomy, outperforming traditional techniques especially in noisy or asymmetric conditions.

Contribution

The paper proposes a novel quadratic fit approach using the maximum intensity pixel and its neighbors for robust centroid measurement, improving accuracy over existing methods.

Findings

The quadratic fit method achieves sub-velocity resolution precision.

It is robust against noise and asymmetric line profiles.

Outperforms traditional centroid measurement techniques.

Abstract

Measuring the centroid of a spectral line is a common problem in astronomy. Many methods have been devised to overcome limitations due to either noise in the spectra or asymmetric profiles, the most common of which are the intensity weighted averages (first moment) or fits of analytical (typically Gaussian) profiles. If the spectral line can be considered a single component, we demonstrate that a simple quadratic fit to the pixel of maximum intensity and its two neighboring pixels provides a robust measure of the line centroid. This approach allows for a sub-velocity resolution precision on the line centroid, without be biases by noise or asymmetric features in the line profile and outperforming traditional methods in most situations.