Images of 2251+158 observed at 15 GHz for epochs 1995 Jul. 29 to 2005 Sep. 17. Gaussian model fit components are superimposed for each image. The restoring beam of each image is presented as a shaded ellipse.

Images of 2251+158 observed at 15 GHz for epochs 2006 Mar. 09 to 2009 Dec. 03. Gaussian model fit components are superimposed for each image. The restoring beam of each image is presented as a shaded ellipse.

Images of 2251+158 observed at 15 GHz for epochs 2010 Jan. 18 to 2010 Nov. 20. Gaussian model fit components are superimposed for each image. The restoring beam of each image is presented as a shaded ellipse.

Images of 2251+158 at 43 GHz.

Separation from the core as function of time shown for all reliably identified components in the VLBI jet of 2251+158.

Inner jet components and their properties. From top to bottom: distance from the core as function of time, position angle of the component relative to the core as function of time, and flux density as function of time. Please note that the bottom image also displays the flux density evolution of the core.

Components of the arc-like structure and their properties. From top to bottom: distance from the core as function of time, position angle of the component relative to the core as function of time, and flux density as function of time.

Outer jet components and their properties. From top to bottom: distance from the core as function of time, position angle of the component relative to the core as function of time, and flux density as function of time.

Coordinates of the arc-components R1, R2, R3, and R4. Dotted lines indicate a cubic regression model to R1, quadratic regression model to R2, and a linear regression model to R3 and R4. The fits are meant to visualize the trends, not to represent an optimum fit to the data.

Flux density monitoring. The top panel shows the single-dish radio flux densities as observed within the Michigan monitoring program. Flux densities observed at 4.8 (red), 8.0 (blue), and 14.5 GHz (green) are shown. Superimposed is the R-band light-curve (black data points) obtained with the Abastumani optical telescope. Note that the two y-axes are labeled differently (the left y-axis describes the radio flux density, the right y-axis the optical magnitude). Please also note that the optical data cover the time between 2000 Jun. 03 and 2012 Feb. 02. The plot at the bottom is an expansion of the plot at the top.