This is from the 2013 owners manual.
http://www.chryslercommercialvehicles.com/dodge/download/pdf/manuals/2013-Challenger-OM-3rd.pdf
21. Vehicle Security Light — If Equipped
This light will flash at a fast rate for approximately
15 seconds, when the vehicle security
alarm is arming, and then will flash slowly
until the vehicle is disarmed.http://www.chryslercommercialvehicles.com/dodge/download/pdf/manuals/2013-Challenger-OM-3rd.pdf