These photoflash bombs only burned for 1/5 of a second or so. They were like a flash bulb. They were not used as target markers. Each was only used for taking a single night picture. They were dropped from 10,000 feet and exploded at a lower altitude.
The bombers stayed on course so they were "over" the target when the flash went off, which was "timed out" to be at the same time that the explosive bombs exploded on the target. I think they were essentially trying to get a single "Strike Attack Vertical" shot, but taken at night.
Here is the location showing the rather distinctive shape of the spit of land.
https://www.google.com/maps/place/43...99!4d25.970413
The oil tank targets were located a little to the NE, right along the river bank starting where the "spit" meets the main bank of the river. It looks like today it is just a long narrow field with a series of circular patterns on the ground where the oil storage tanks were.