Directly from the user manual, Page 5 under "AC/DC Power Sources":
DC Models ONLY
"This TV model operates on both standard household current (120 volt, 60 Hz AC) and
car battery (12 volt negative ground DC) through the cigarette lighter. An AC power cord and a car cigarette lighter adapter cord are supplied.
Insert the AC power cord into the connection on the rear of the TV. Connect the two pronged plug into an AC outlet (120 volt, 60Hz). If you are unable to insert the plug fully into the wall outlet, try reversing it. If the plug does not fit, contact an electrician. Do not force the plug or defeat the safety purpose of the polarized plug."
The manual goes on to describe the vehicle installation which is identical to the household, with the only difference being the car plug goes into the DC side of the power connections at the back.
There are several kinds of power cord available for older TV models. Unfortunately, after an exhaustive search, I was not able to locate a photo of the back of that model television.
However, I have included three of the typical US power connectors found on a great many devices and in the majority of cases, one of these cords will likely be the one you need. They can be found at most local stores such as Wal-Mart, or can be ordered online from Amazon. Also, the cored generally only fit in one direction, especially if the cord happens to be polarized (thin blade and wide blade).
I hope this helps!
Panasonic CT 13R50 Manuals and User Guides