HVK is short for Hava Kuvvetleri Komutanlığı, which is Turkish for Air Force Command. Looking at the whole, it doesn't look this C130 is on a 'real' mission but on a walk-about.

@ 22:38 UTC : The same C130 showed up again this time as HVKK1240 returning to base from Eskişehir. As it was descending towards Kayseri it squawked 7700 meaning it had an in-flight emergency. It looks like it landed 11 minutes later. Maybe we'll find out the details later.