Photometric monitoring of the blazar 3C 345 for the period 1996 - 2006

TL;DR

This study presents a decade-long photometric monitoring of blazar 3C 345, revealing its variability patterns, flaring activity, and color-magnitude relationship, with no significant intra-night variability detected.

Contribution

First comprehensive long-term BVRI photometric dataset for 3C 345, analyzing variability, color behavior, and intra-night stability over ten years.

Findings

Total variability amplitude of ~2 mag in V and R bands.

Flaring activity peaks in 1998/99 and 2001.

No significant intra-night variability observed.

Abstract

We present the results of the blazar 3C 345 monitoring in Johnson-Cousins BVRI bands for the period 1996 - 2006. We have collected 29 V and 43 R data points for this period; the BI light curves contain a few measurements only. The accuracy of our photometry is not better than 0.03 mag in the VR bands. The total amplitude of the variability obtained from our data is 2.06 mag in the V band and 2.25 mag in the R one. 3C 345 showed periods of flaring activity during 1998/99 and 2001: a maximum of the blazar brightness was detected in 2001 February - 15.345 mag in the V band and 14.944 mag in the R one. We confirm that during brighter stages 3C 345 becomes redder; for higher fluxes the colour index seems to be less dependent on the magnitude. The intra-night monitoring of 3C 345 in three consecutive nights in 2001 August revealed no significant intra-night variability; 3C 345 did not show evident flux changes over timescales of weeks around the period of the intra-night monitoring. This result supports the existing facts that intra-night variability is correlated with rapid flux changes rather than with specific flux levels.