by Phil Rowe
The notice on bulletin board made it clear. Tonight we shoot the stars. It's a part of our early training to become Air Force navigators. Groups of eight or ten aviation cadets were told to report at 2030 hours behind the main classroom building.
It was just about dark on that March evening when we gathered for the first of several star-shooting sessions. We'd been on the go since 0530 that morning, but we still had three hours more before being able to get some much-needed rest. It seemed to us that testing the endurance of cadets was part of the program.
Our outdoor classroom was not much. On an old concrete volleyball court they'd mounted a framework of elevated steel pipe. The structure was a network of horizontal bars supported by regularly spaced vertical columns. Every six or eight feet of that checkerboard-like grid of work stations was punctuated by small step stools upon which we students would stand to make our observations of the stars, moon and planets.
But first we had to make some important calculations and get our watches synchronized with a precise master clock. Time is the essence of accurate navigtion, for the stars move across the heavens one degree every four minutes. Actually, of course, it's the earth that rotates at that rate. The stars stay put and we move.
The exercise for the evening began with each student making a set of calculations to predict the position of selected stars at various time intervals during the training session. Azimuth and elevation angles were calculated which correlated to our Texas position in longitude and latitude.
It was our job to make accurate observations of the selected stars to determine the precise elevation angles for the chosen times. Then we were expected to apply the various corrections to adjust the measurements for a variety of anticipated errors. For example, one error was atmospheric distortion, as a function of observed angle and our altitude above sea level. The air above us distorts the accuracy of observed star elevation angles.
Some of us were given hand-held sextants, octants really. Those relics of W.W.II were tough to use because it was nearly impossible to hold them absolutely steady. Even by making observations over several minutes and time-averaging the elevation angles, we made errors simply by not holding the instruments steady enough.
Others were given periscopic sextants. They are far superior in accuracy, for they are mounted on a swivel support and not hand held. Additionally they have better optics, an averaging timer mechanism and an easy-to-use bubble leveling reference. Elevation angles with these devices were much better than with the others. After each observation we were required to plot on navigational charts the error-corrected lines of position. Those lines were supposed to pass exactly through the coordinates for our Texas training base. They were supposed to, but they didn't always. Some of our calculations were off. Observations were flawed, and correction values for the various known errors were inexact. In some cases our plotting was several miles off. That didn't help our self-confidence one bit.
If we couldn't get things right on the ground, a stable firm work platform, what would our observations be like in a bouncy airplane? It was a humbling experience for most of us. But we quickly learned from our instructors that we would improve as we mastered our technique. Of that we were still uncertain. It would be several weeks of more ground schooling and night star-shooting sessions before we actually got to try our celestial navigation skills in the air. All this took place at Ellington Air Force Base, Texas in the Spring of 1953.
Boy, was that a long time ago.