# (Astrophysics) Determine the apparent transverse velocity from a radio image

fishlens
Homework Statement:
In the figure below we see a component of a jet of a galactic nucleus which is moving away from its nucleus. The distance to the galactic nucleus is D. What is the observed apparent transverse velocity? And what is the value of the Lorentz factor needed to explain this motion?

Figure : https://imgur.com/a/t0m7kCr
Relevant Equations:
gamma = 1/sqrt(1-(v/c)^2) (gamma - Lorentz factor, v - velocity, c - speed of light)
See the attached figure.

I understand that we look for the apparent transverse velocity v , for example through v = d/t (d - distance, t - time). The distance to the galactic nucleus is known as D. Though I am not sure how to read off the time from this figure.

Mentor
The numbers next to the images are (decimal) years. The first image is from mid 1977, the last from mid 1980.

fishlens
Hi, thanks for the reply @m
The numbers next to the images are (decimal) years. The first image is from mid 1977, the last from mid 1980.