Orbit speed

The planet Yavin was an orange gas giant, nearly 200,000 kilometers in diameter. It had dozens of moons, three of which could support humanoid life. The innermost habitable moon was designated Yavin 4, and was covered by steamy jungles and volcanic mountain ranges.

(...)

On the Death Star, Darth Vader stood behind a chair in the conference room and watched Grand Moff Tarkin respond to a signal from the comlink on the large round table. Tarkin pressed a button and said, “Yes.”
Over the comlink intercom, a voice reported, “We are approaching the planet Yavin. The Rebel base is on a moon on the far side. We are preparing to orbit the planet.”

(...)

On the Death Star, Grand Moff Tarkin and Darth Vader watched a computer monitor that showed the space station’s position in relation to the planet Yavin and the moon Yavin 4. As the planetary diagrams moved over and past each other on the monitor, a voice from the intercom announced, “Orbiting the planet at maximum velocity. The moon with the Rebel base will be in range in thirty minutes.”
“This will be a day long remembered,” Vader said. “It has seen the end of Kenobi. It will soon see the end of the Rebellion.”

***

Star Wars®: Episode IV: A New Hope™ Chapter 13