106:38:04 Fullerton: Endeavour, Houston. Your T-2 now.
[Al begins pitching Endeavour to keep Hadley Base visible through the sextant.]
106:38:10 Worden: Roger. I have the landing site in view.
106:38:13 Fullerton: Roger. Very good. [Long pause.]
106:39:29 Worden: Okay. And, Houston; Endeavour. I've got the LM.
106:39:34 Fullerton: Roger, Al.
106:39:39 Worden: I'll give you the coordinates in a minute.
106:39:14 Fullerton: Okay.
106:39:43 Worden: But he's almost directly north of Index.
106:39:46 Fullerton: Roger. Understand.
106:40:28 Fullerton: Endeavour, Houston. You're TCA now.
[Al is making his closest approach to the landing site and is taking marks on Falcon so the LM's position can be computed.]
106:40:34 Worden: Roger.
106:40:48 Worden: Okay. He's about half way between Index and the next crater off toward the North Complex. He's sitting right by a very small crater. And, as soon as I lose them here, I'll give you the coordinates, but he's quite plain down there.
106:41:05 Fullerton: Roger, Al.
106:42:22 Worden: Houston, Endeavour.
106:42:24 Fullerton: Go ahead, Al, Houston.
106:42:28 Worden: Okay, Gordo. If you look at the grid map, 1 to 250; that's HR25-11, he's on BR, .5, 75.5.
106:42:49 Fullerton: Okay; Copy. Baker Romeo, .5 and 75.5?
106:42:58 Worden: That's affirm.
106:42:59 Fullerton: Okay; thank you.
[Long comm break.]
[Worden, from the 1971 Technical Debriefing - "As I came over the landing site, I saw the LM shadow very clearly, and once I had identified the shadow, then I could also see the LM in the sextant. I watched the LM until I was near nadir, until I was almost to TCA, and then I took out the visual map, the 1 to 25,000 scale, in the CSM Lunar Landmark Map Book, and marked the spot where I saw the LM. That was BR.5 and 75.5, in the Lunar Landmark Book. One more comment on the LM acquisition, and, again, it's a comment that's been made before on landmark tracking. Once the LM was spotted, there was no problem at all tracking with the optics. Of course, at this time, I was in a 60-mile circular in orb-rate, and the [angular] rates were very low. But even at the low altitudes, there was no trouble tracking any landmark that you selected with the optics, in either orb-rate or inertial hold [keeping the spacecraft steady with respect to the stars]. The optics were very smooth in tracking and very positive. As long as the trunnion angle is great enough so that you don't go or close to zero trunnion angle, any landmark you pick is fairly easy to track."]
[The 28-power sextant has two degrees of freedom by virtue of an articulated optical path. An exterior view of the Apollo 11 Command Module Columbia shows the orifices in the spacecraft's wall for the sextant and scanning telescope. The sextant looks through the slit in the disc that is nearly flush with the surface of the CM. Rotation of this disc represents the shaft angle. The slit across this disc accommodates the objective lens which can scan across the slit. The angle of the lens within this slit is called the trunnion angle with the central position being the zero angle.]
[Tracking an object; a star, planet or landmark; is achieved with a combination of motion in the shaft and trunnion axes, providing the attitude of the spacecraft has brought the object into the range of the optics. However, if the tracking of an object brings the trunnion near the middle of the slit, the zero calibration of its travel, then there has to be a relatively large rotation of the shaft to keep alignment and if it gets too close to zero, the shaft cannot be rotated fast enough to maintain a fix on the object.]
[As seen in the picture of Columbia The sextant, through which Al was looking at the LM, is mounted on the side of the Command Module opposite the main hatch. Therefore, the windows and, more importantly, the SIM bay are all pointing essentially out into deep space. With the upcoming operation of the SIM bay instruments in mind, Al reorients Endeavour with the bay facing the Moon and the spacecraft pointing forward in the direction of motion. To keep the SIM bay properly pointed, the spacecraft must be rotated in orb-rate. P20 is the program in the computer which takes care of this.]