Relaxing floating in the backyard pool on a hot afternoon we witnessed a white object stationary high up in the atmosphere. It appeared to fade in. Half the size of a small fingernail. Positioned roughly over Tea Tree Gully area.The object remained in the same position for over 10 minutes, during this time, i rushed inside to get the video camera upon finding the battery was flat, so i rushed back inside to get the camera. My guests said the object seem to ascend and disappeared after 14 minutes. Later it returned in the same position in the sky, i ran inside again to get the camera i just put back and it ascended and disappeared. The object looked as if it was pulsating slowly. Amazingly it remained in the same position without any movement. It looked as if it was higher than a normal 737-800 on route to Sydney travelling over Adelaide west to east.Thought Mufon could be interested in this sighting for information in hindsight.