Variability and spectral variation of 3C 66A

TL;DR

This study analyzes multi-year optical observations of 3C 66A, revealing long-term variability, spectral flattening during brightening, and a wavelength-dependent time lag, enhancing understanding of blazar emission mechanisms.

Contribution

The paper provides a detailed analysis of optical variability and spectral changes in 3C 66A over several years, including time lag detection and spectral behavior during brightness variations.

Findings

Long-term optical variability observed in 3C 66A.

Spectral flattening correlates with increased brightness.

Detected time lag with shorter wavelengths leading longer ones.

Abstract

3C 66A was monitored by the BATC(Beijing-Arizona-Taipei-Connecticut) telescope from 2005 to 2008,1994 observations were obtained on 89 nights. Detailed research and analysis was performed on these observations in this paper. A long term burst occurred in the whole light curve. No intra-day variability was claimed in our campaign by intra-night light curve analysis. Time lag of shorter wavelenth preceding longer wavelength was shown by correlation analysis. The results showed that the optical spectral shape turned flatter when the source brightened, and the spectral variability indicator was bigger on shorter time-scale as determined by the color indices variation analysis.