# Hohmann transfer using GMAT software

I am trying to plot an orbit using gmat. I fixed apogee(RadApo) and perigee(RadPer) for the inner orbit(green) and inserted an impulsive burn.

I got the desired shape of the outer orbit but I am unable to know how do I find relation between the velocity on impulsive burn (element-1) and the apogee of the second orbit.

It would be very helpful of anyone if I can get this relation or If I can know what is the RadApo(apogee) for the second orbit(Red)

Assume the velocity increment is at the perigee and along the velocity then the new velocity is $$V$$, calcualate the semimajor axis from the vis viva equation:
$$V^2 = \mu (2/r - 1/a)$$
The apogee distance is then $$r_a = 2a-r_p$$
If $$1/a$$ is zero you have a parabolic orbit, if negative it is hyperbolic.