reduced scale topographical chart indicated that the negative included a region of the earth measuring approximately 11.5 km on a side.

The following information was recorded on one side of the film:

Frame counter: 909
Altimeter: 10,000 feet
Bubble level: Approx. level
                         C = 152.44
                         Nr 21186
             Clock: 08:25 am local time
   Notations:      ARENAL
                         10,000 feet
                          4-9-71 (September 4, 1971)
                          R. L. B.

Handwritten between the frame counter and the above information is the notation: 300 L- 11 M - 13.

On board the aircraft were four men, namely: Sergio L. V., specialist in aerial photography, as well as Omar A. (pilot), Juan B. C., geographer, and Francisco R. R., topographer. No member of the crew observed anything unusual during the flight.

Figure 4 is a photographic positive black-and-white enlargement of intermediate contrast of the disc, showing (a) a dark edge across the top and upper-right corner, which is the edge of the frame and fiduciary mark included for measurement purposes, (b) the shoreline, also for measurement purposes, and (c) the ellipsoidal disc. This figure is oriented with true North facing up.

A number of features are worthy of note on Figure 4.

First, the disc image appears to possess light/dark shading that is typical of a three-dimensional object which is illuminated by sunlight. At this time and location, the sun's azimuth was 85.4 degrees (clockwise from true North) and altitude was 16.7 degrees which explains the lateral displacement of the cloud shadows from the cloud locations.

Second, the generally triangular dark region on the right-hand side of the disc cannot be a solar shadow cast by the (assumed) opaque disc from the right-hand side. If the disc is an opaque, flat conical section of revolution (the dark spot being the tip of the cone) and if the right side is tipped upward, then the entire surface of the disc should be dark. It is more likely that the light and dark regions are surface markings.

Figure 5 shows measured and calculated parameters for this image. The longitudinal axis of the disc was 7 degrees CW from true North. The total included angle of the dark triangular region was about 110 degrees arc with the most northerly edge of this shadow 38 degrees from true North. The approximate centerline of the triangular shadow region was 93 degrees CW from true North.