Handling Redirected URL with dynamic session value

We are testing a angular JS based application which calls a external system for authentication and authorization. 

Problem is when we hit the applications launch page URL a new redirected (response code: 302) is getting generated with dynamic value. 

In a given application we can correlate the dynamic value which is available in any of the previous response. But in above case, redirected URL is coming with dynamic value. 

For Example:

Launch URL: https://abc.com

when we hit above in browser we are navigated to external to "abc" system. a url with 302 response code comes in with two dynamic value.

for example: 

https://athuserver.com/session=qwertyieds&state=weerye

note: italic dynamic value.

from this we are getting session of subsequent pages where we able to correlate. Where we stuck is one first url with session value.

Please help us with your valuable inputs.

Thanks in advance!!!

Krishnan.