Multi-Band Optical Variability Characteristics of the γ-ray emitting blazar 1ES 0647+250 during its 2020 flare
Abstract
We present a multi-band optical variability study of the γ-ray emitting high-synchrotron-peaked blazar 1ES~0647+250 during its enhanced optical activity in 2020. The analysis utilizes 107 epochs of high-precision B, V, and R-band photometry obtained with the 75 cm telescope at the Vainu Bappu Observatory, combined with high-cadence zg and zr survey data from the Zwicky Transient Facility. The combined light curves reveal coherent variability across all optical filters, with the source reaching a peak R-band magnitude of 15.74 mag. We calculated the variability amplitude, finding the highest intrinsic variability in the B- band. Spectral analysis using color--magnitude diagrams reveals a statistically significant ``Bluer-When-Brighter'' trend, supported by a Pearson correlation coefficient of r = 0.68 (p < 0.001) for the (V−R) index. Furthermore, the discrete correlation function analysis indicates a near-zero time lag between the V and R bands, suggesting simultaneous emission within the observational cadence. The observed spectral hardening is consistent with synchrotron-dominated optical emission, likely associated with enhanced particle acceleration within the jet during the active phase of 1ES~0647+250.
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BibTeX
@misc{pandian2026multiband,
title = {{Multi-Band Optical Variability Characteristics of the $γ$-ray emitting blazar 1ES 0647+250 during its 2020 flare}},
author = {K. Subbu Ulaganatha Pandian and C. S. Stalin and S. Muneer and S. Umayal and Aditi Agarwal and Amit Kumar Mandal and B. Natarajan},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.27630},
eprint = {2609.27630},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.27630},
}
RIS
TY - UNPB
TI - Multi-Band Optical Variability Characteristics of the γ-ray emitting blazar 1ES 0647+250 during its 2020 flare
AU - K. Subbu Ulaganatha Pandian
AU - C. S. Stalin
AU - S. Muneer
AU - S. Umayal
AU - Aditi Agarwal
AU - Amit Kumar Mandal
AU - B. Natarajan
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.27630
UR - https://arxiv.org/abs/2609.27630
AB - We present a multi-band optical variability study of the γ-ray emitting high-synchrotron-peaked blazar 1ES~0647+250 during its enhanced optical activity in 2020. The analysis utilizes 107 epochs of high-precision B, V, and R-band photometry obtained with the 75 cm telescope at the Vainu Bappu Observatory, combined with high-cadence z_g and z_r survey data from the Zwicky Transient Facility. The combined light curves reveal coherent variability across all optical filters, with the source reaching a peak R-band magnitude of 15.74 mag. We calculated the variability amplitude, finding the highest intrinsic variability in the B- band. Spectral analysis using color--magnitude diagrams reveals a statistically significant ``Bluer-When-Brighter'' trend, supported by a Pearson correlation coefficient of r = 0.68 (p < 0.001) for the (V−R) index. Furthermore, the discrete correlation function analysis indicates a near-zero time lag between the V and R bands, suggesting simultaneous emission within the observational cadence. The observed spectral hardening is consistent with synchrotron-dominated optical emission, likely associated with enhanced particle acceleration within the jet during the active phase of 1ES~0647+250.
ER -