Who was in command of the Enterprise during the mission in “Time's Arrow”?

Question

During the episode "Time's Arrow", six executive officers are trapped in the 19th century for several days: La Forge, Troi, Crusher, Picard, Riker, and Data. The latter three are the captain, second-, and third-in-command. Who was in command of the Enterprise while they were on this mission? Was it Worf?

If so, who was in command during the short period of time between when Picard beamed down to the surface of Devidia II and when he ordered Worf to return to the ship? Ro Laren?

Answer 1

The Enterprise-D was a big ship, with hundreds of officers on board, probably including many in the command division with lieutenant or lieutenant commander grade ranks. I'd guess that it was probably someone in that category that was simply never part of a story and never shown onscreen.

EDIT:

Yes, this answer is speculation, but the episode simply does not say. But let me try to add some meat to the answer:

In the pilot episode of DS9, O'Brien wanders onto the bridge to say goodbye before transferring over to the station. He speaks to the current officer on duty, a woman who we have never seen before and is given no name. Someone like her was probably briefly given command of the ship in the "Time's Arrow" situation described in the question.

Answer 2

The ship normally operated with 3 (and sometimes 4) duty shifts (designated Alpha, Beta, Gamma, etc.). The officers stuck in the past were all Alpha shift officers meaning there were at least two other groups of officers fully capable of operating the ship in their absence.

It seems likely the officer on duty in "Emissary", mentioned by @MattPeterson, was from one of these other shifts.

Answer 3

Memory-Alpha lists Worf as the third officer for the Enterprise-D. This means that in the absence of Picard, Riker, and Data, he was in command until their return.

Even if an officer has the same (or even higher) rank than a bridge officer, the bridge officer holds seniority. This can be seen in "The Arsenal of Freedom" when La Forge is given command of the bridge, and the chief security officer (of higher rank) attempts to take command from him.

In the absence of any bridge officers the highest ranking individual has the right to take command, in an emergency. If it seemed likely that the entire compliment of bridge officers were never coming back they would contact Starfleet to instructions.